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Triple negative breast cancer (TNBC) subtype is the most aggressive and conventional chemotherapy is the standard treatment since lacks validated targeted therapies. Thus, there is an unmet need for improved in vitro research tools, including scaffolds for the formation of tumoroids. In this preliminary study, the main aim was to assess the tumoroid-forming potential of polycaprolactone (PCL)/polystyrene (PS) scaffolds. Six different polymer solutions, varying PCL/PS ratios, were formulated and PCL/PS scaffolds were manufactured using the electrospinning technique. PCL/PS structures were characterized by SEM imaging. Subsequently, a sterilization assay was performed to evaluate potential alterations derived from this process. Afterwards, TNBC MDA-MB-231 cells were cultured on PCL/PS structures for 10 days. The findings revealed that cells cultured on PCL 100/PS 0, PCL 80/PS 20, and PCL 60/PS 40 matrices exhibited the formation of tumoroids. In conclusion, PCL/PS scaffolds offer a valuable in vitro tool for tumoroid formation.

In this research, a novel natural-based polymer, the Aloe Vera biopolymer, is used to improve the mobility of the injected water. Unlike most synthetic chemical polymers used for chemical-enhanced oil recovery, the Aloe Vera biopolymer is environmentally friendly, thermally stable in reservoir conditions, and compatible with reservoir rock and fluids. In addition, the efficiency of the Aloe Vera biopolymer was investigated in the presence of a new synthetic nanocomposite composed of KCl-SiO2-xanthan. This chemically enhanced oil recovery method was applied on a sandstone reservoir in Southwest Iran with crude oil with an API gravity of 22°. The Aloe Vera biopolymer’s physicochemical characteristics were initially examined using different analytical instruments. The results showed that the Aloe Vera biopolymer is thermally stable under reservoir conditions. In addition, no precipitation occurred with the formation brine at the salinity of 80,000 ppm. The experimental results showed that adding ethanol with a 10% volume percentage reduced interfacial tension to 15.3 mN/m and contact angle to 108°, which was 52.33 and 55.56% of these values, respectively. On the other hand, adding nanocomposite lowered interfacial tension and contact angle values to 4 mN/m and 48°, corresponding to reducing these values by 87.53 and 71.42%, respectively. The rheology results showed that the solutions prepared by Aloe Vera biopolymer, ethanol, and nanocomposite were Newtonian and fitted to the Herschel-Bulkley model. Finally, core flooding results showed that the application of a solution prepared by Aloe Vera biopolymer, ethanol, and nanocomposite was effective in increasing the oil recovery factor, where the maximum oil recovery factor of 73.35% was achieved, which could be attributed to the IFT reduction, wettability alteration, and mobility improvement mechanisms.

Understanding the hydrodynamic alignment of colloidal rods in polymer solutions is pivotal for manufacturing structurally ordered materials. How polymer crowding influences the flow-induced alignment of suspended colloidal rods remains unclear when rods and polymers share similar length scales. We tackle this problem by analyzing the alignment of colloidal rods suspended in crowded polymer solutions and comparing that to the case where crowding is provided by additional colloidal rods in a pure solvent. We find that the polymer dynamics govern the onset of shear-induced alignment of colloidal rods suspended in polymer solutions, and the control parameter for the alignment of rods is the Weissenberg number, quantifying the elastic response of the polymer to an imposed flow. Moreover, we show that the increasing colloidal alignment with the shear rate follows a universal trend that is independent of the surrounding crowding environment. Our results indicate that colloidal rod alignment in polymer solutions can be predicted on the basis of the critical shear rate at which polymer coils are deformed by the flow, aiding the synthesis and design of anisotropic materials., source:https://pubs.acs.org/doi/10.1021/acs.macromol.2c00769

Understanding the hydrodynamic alignment of colloidal rods in polymer solutions is pivotal for manufacturing structurally ordered materials. How polymer crowding influences the flow-induced alignment of suspended colloidal rods remains unclear when rods and polymers share similar length scales. We tackle this problem by analyzing the alignment of colloidal rods suspended in crowded polymer solutions and comparing that to the case where crowding is provided by additional colloidal rods in a pure solvent. We find that the polymer dynamics govern the onset of shear-induced alignment of colloidal rods suspended in polymer solutions, and the control parameter for the alignment of rods is the Weissenberg number, quantifying the elastic response of the polymer to an imposed flow. Moreover, we show that the increasing colloidal alignment with the shear rate follows a universal trend that is independent of the surrounding crowding environment. Our results indicate that colloidal rod alignment in polymer solutions can be predicted on the basis of the critical shear rate at which polymer coils are deformed by the flow, aiding the synthesis and design of anisotropic materials., source:https://pubs.acs.org/doi/10.1021/acs.macromol.2c00769

Interactions between colloidal particles can be modelled by particles grafted with polymers. In this work, structural and physical properties of colloids are investigated under variation of parameters such as pH, ionic strength, and temperature, where aggregation and cluster formation can be monitored in aqueous solution. Being the subject of our work, in particular, we show that linear or polymer-like clusters can be formed if long-ranged repulsive barriers are combined with very short-ranged attractive minimums stimulating particles to form highly anisotropic structures. This is adjusted by changing the properties of particles and the dispersing medium. Besides, we utilize Metropolis Monte Carlo (MC) simulation to investigate the behavioural change of these particles with a focus on the types of clusters formed. A simplistic potential of mean force is adopted for the simulations, but we also invoke a more elaborate model, to demonstrate that similar interactions can be obtained when the grafted chains are treated explicitly. An important criterion in these studies is that the particle size is large enough to allow structural analyses via microscopy. The range of electrostatic interactions is adjusted by the ionic strength, and the strength of the short-ranged attraction is changed via hydrophobicity regulation of the grafted layer through temperature variation. The results revealed that highly anisotropic structures which resemble linear or branched polymers were the clusters at equilibrium. We could also investigate the effect of polymer addition to the particle dispersions. We could detect a non-monotonic temperature dependent aggregation of particles from attraction to repulsion to attraction, where the polymer-mediated interactions were repulsive. The results were validated against experiments.The next phase of this work is devoted to the study on capillary induce phase transitions with an experimental focus on polymer solutions containing PNIPAM at the presenc

Per motius de confidencialitat, el document original conté altra informació no inclosa en el fitxer de consulta, Un gel és un material polimèric amb una estructura tridimensional flexible capaç de ser inflada per un líquid. Son materials hidròfils i per tant, tenen una gran afinitat a l’aigua. A més tenen propietats físiques molt interessants com la seva elasticitat. És per això que en aquest projecte s’estudiarà la possibilitat de afegir dins l’estable estructura de l’hidrogel un principi actiu, en aquest cas un aminoàcid. El següent estudi consisteix en trobar una estructura estable on l’aminoàcid quedi perfectament retingut pel gel. Per una altre banda s’estudiarà el comportament del gel en un medi semblant a la suor humana com és el sèrum fisiològic. La finalitat d’aquest projecte és la determinació de la quantitat de principi actiu que el gel és capaç d’alliberar al medi depenent de l’estructura i composició del mateix.

Thermoresponsive polymers with a lower critical solution temperature, LCST, have attracted interest in the development of new ``smart materials'', which change properties in response to external stimuli. Polymers with an LCST near physiological temperatures are especially relevant in biomedical applications, most notably perhaps in drug delivery systems. The aim of this work is to investigate polymer solutions with an LCST using a coarse-grained model where the monomers of the polymer chains exist in one of two states; one solvophilic and one solvophobic state, where the degeneracy of the solvophobic state is higher than that of the solvophilic. Metropolis Monte Carlo simulations were performed on both single-chain and multiple-chain systems, and on chain lengths varying between 20 and 400 monomers. Simulations on single-chain systems showed a collapse for chains with 40 or more monomers, while the investigated multiple-chain systems of all chain lengths aggregated. Due to fluctuations in the temperature at which the collapse occurred, as well as inconsistencies between simulations performed by decreasing and increasing the temperature, further investigations are needed to determine the limitations of the model and its usefulness in describing polymer solution behaviour., Polymerer är långa kedjor av upprepade segment och finns både som naturliga polymerer (proteiner, DNA, gummi, och cellulosa) och som syntetiskt framställda polymerer (plaster, nylon, etc.). Många polymerer är känsliga för ändringar i deras miljö och termoresponsiva polymerer, som har studerats i detta arbete, ändrar egenskaper drastiskt vid ändringar i temperaturen. Vid en viss kritisk temperatur, som är specifik för den enskilda polymeren, går dessa polymerer från att vara utsträckta kedjor, lösliga i medlet de befinner sig i, till att kollapsa och bilda tätpackade kluster som kan fällas ut från lösningen. Termoresponsiva polymerer är intressanta att studera på grund av deras applikationer som "smarta material". De kan till exempel användas inom transportsystem för läkemedel som en del av läkemedelskapseln, då de skulle kunna reagera på temperaturen i omgivningen för att veta när kapseln har kommit rätt och frisätta läkemedlet på en lämplig plats i kroppen. Datorsimuleringar med dessa typer av polymerer kan ge en större inblick i hur och varför polymererna kollapsar, samt hur olika egenskaper av polymeren och hur yttre faktorer påverkar temperaturen polymererna kollapsar vid. Simuleringar av större polymersystem, med många och långa kedjor är mycket tidskrävande och det är därför önskvärt att kunna beskriva polymerernas beteenden vid olika temperaturer med en enklare modell. I detta arbete har därför en enklare modell användts för att studera polymerlösningar. Både enstaka polymerer och större system med flera polymerkedjor har studerats och det har undersökts om det går att se en direkt koppling mellan kollapsen av en kedja och aggregeringen av ett helt system till ett hoppackat kluster. Simuleringarna har visat att modellen kan beskriva den plötsliga kollaps av polymerer som sker vid en viss temperatur både för enstaka polymerer och för flera polymerer. Det fanns dock en variation i när denna kollaps skedde för båda systemen och därför kunde inte en specifik temp

Thermoresponsive polymers with a lower critical solution temperature, LCST, have attracted interest in the development of new ``smart materials'', which change properties in response to external stimuli. Polymers with an LCST near physiological temperatures are especially relevant in biomedical applications, most notably perhaps in drug delivery systems. The aim of this work is to investigate polymer solutions with an LCST using a coarse-grained model where the monomers of the polymer chains exist in one of two states; one solvophilic and one solvophobic state, where the degeneracy of the solvophobic state is higher than that of the solvophilic. Metropolis Monte Carlo simulations were performed on both single-chain and multiple-chain systems, and on chain lengths varying between 20 and 400 monomers. Simulations on single-chain systems showed a collapse for chains with 40 or more monomers, while the investigated multiple-chain systems of all chain lengths aggregated. Due to fluctuations in the temperature at which the collapse occurred, as well as inconsistencies between simulations performed by decreasing and increasing the temperature, further investigations are needed to determine the limitations of the model and its usefulness in describing polymer solution behaviour., Polymerer är långa kedjor av upprepade segment och finns både som naturliga polymerer (proteiner, DNA, gummi, och cellulosa) och som syntetiskt framställda polymerer (plaster, nylon, etc.). Många polymerer är känsliga för ändringar i deras miljö och termoresponsiva polymerer, som har studerats i detta arbete, ändrar egenskaper drastiskt vid ändringar i temperaturen. Vid en viss kritisk temperatur, som är specifik för den enskilda polymeren, går dessa polymerer från att vara utsträckta kedjor, lösliga i medlet de befinner sig i, till att kollapsa och bilda tätpackade kluster som kan fällas ut från lösningen. Termoresponsiva polymerer är intressanta att studera på grund av deras applikationer som "smarta material". De kan till exempel användas inom transportsystem för läkemedel som en del av läkemedelskapseln, då de skulle kunna reagera på temperaturen i omgivningen för att veta när kapseln har kommit rätt och frisätta läkemedlet på en lämplig plats i kroppen. Datorsimuleringar med dessa typer av polymerer kan ge en större inblick i hur och varför polymererna kollapsar, samt hur olika egenskaper av polymeren och hur yttre faktorer påverkar temperaturen polymererna kollapsar vid. Simuleringar av större polymersystem, med många och långa kedjor är mycket tidskrävande och det är därför önskvärt att kunna beskriva polymerernas beteenden vid olika temperaturer med en enklare modell. I detta arbete har därför en enklare modell användts för att studera polymerlösningar. Både enstaka polymerer och större system med flera polymerkedjor har studerats och det har undersökts om det går att se en direkt koppling mellan kollapsen av en kedja och aggregeringen av ett helt system till ett hoppackat kluster. Simuleringarna har visat att modellen kan beskriva den plötsliga kollaps av polymerer som sker vid en viss temperatur både för enstaka polymerer och för flera polymerer. Det fanns dock en variation i när denna kollaps skedde för båda systemen och därför kunde inte en specifik temp

The published manuscript is available at EurekaSelect via http://www.eurekaselect.com/openurl/content.php?genre=article&doi=10.2174/0929867324666170920161246, Composed in a large extent of water and due to their non-adhesiveness, hydrogels found their way to the wound dressing market as materials that provide a moisture environment for healing while being comfortable to the patient. Hydrogels’ exploitation is constantly increasing after evidences of their even broader therapeutic potential due to resemblance to dermal tissue and ability to induce partial skin regeneration. The innovation in advanced wound care is further directed to the development of so-called active dressings, where hydrogels are combined with components that enhance the primary purpose of providing a beneficial environment for wound healing. The aim of this mini-review is to concisely describe the relevance of hydrogel dressings as platforms for delivery of active molecules for improved management of difficult-to-treat wounds. The emphasis is on the most recent advances in development of stimuli-responsive hydrogels, which allow for control over wound healing efficiency in response to different external modalities. Novel strategies for monitoring of the wound status and healing progress based on incorporation of sensor molecules into the hydrogel platforms are also discussed., Peer Reviewed, Postprint (author's final draft)

[EN] The impact morphology of dilute polymer solution drops on a heated surface is studied experimentally by means of high-speed imaging, with respect to the following parameters: surface temperature; impact Weber number; polymer concentration; polymer molecular weight. In addition to impact morphologies observed in Newtonian drops (deposition, rebound, secondary atomisation and breakup/splashing), three new impact regimes have been identified: (i) a single satellite droplet ejected in the direction of bouncing but tethered to the main drop by a thin liquid filament; (ii) a splashing-like behaviour (semi-splashing), where the rim instability generates satellite droplets tethered to the lamella by thin liquid filaments; (iii) a spray-like behaviour (semi-spray), where a fine secondary atomisation generated upon impact is quickly absorbed back into the drop globule. Experiments were carried out using drops of aqueous polyethylene oxide (PEO) solutions, with mass concentrations of 100 ppm, 200 ppm and 400 ppm, and PEO molecular weights of 2 MDa, 4MDa, and 8MDa. The impact morphology on a polished aluminium surface with temperatures ranging between 160°C and 400°C was investigated for impact Weber numbers between 20 and 170, taking side view images of impacting drops at a rate of 1,000 frames per second.

[EN] The impact morphology of dilute polymer solution drops on a heated surface is studied experimentally by means of high-speed imaging, with respect to the following parameters: surface temperature; impact Weber number; polymer concentration; polymer molecular weight. In addition to impact morphologies observed in Newtonian drops (deposition, rebound, secondary atomisation and breakup/splashing), three new impact regimes have been identified: (i) a single satellite droplet ejected in the direction of bouncing but tethered to the main drop by a thin liquid filament; (ii) a splashing-like behaviour (semi-splashing), where the rim instability generates satellite droplets tethered to the lamella by thin liquid filaments; (iii) a spray-like behaviour (semi-spray), where a fine secondary atomisation generated upon impact is quickly absorbed back into the drop globule. Experiments were carried out using drops of aqueous polyethylene oxide (PEO) solutions, with mass concentrations of 100 ppm, 200 ppm and 400 ppm, and PEO molecular weights of 2 MDa, 4MDa, and 8MDa. The impact morphology on a polished aluminium surface with temperatures ranging between 160°C and 400°C was investigated for impact Weber numbers between 20 and 170, taking side view images of impacting drops at a rate of 1,000 frames per second.

[EN] The impact morphology of dilute polymer solution drops on a heated surface is studied experimentally by means of high-speed imaging, with respect to the following parameters: surface temperature; impact Weber number; polymer concentration; polymer molecular weight. In addition to impact morphologies observed in Newtonian drops (deposition, rebound, secondary atomisation and breakup/splashing), three new impact regimes have been identified: (i) a single satellite droplet ejected in the direction of bouncing but tethered to the main drop by a thin liquid filament; (ii) a splashing-like behaviour (semi-splashing), where the rim instability generates satellite droplets tethered to the lamella by thin liquid filaments; (iii) a spray-like behaviour (semi-spray), where a fine secondary atomisation generated upon impact is quickly absorbed back into the drop globule. Experiments were carried out using drops of aqueous polyethylene oxide (PEO) solutions, with mass concentrations of 100 ppm, 200 ppm and 400 ppm, and PEO molecular weights of 2 MDa, 4MDa, and 8MDa. The impact morphology on a polished aluminium surface with temperatures ranging between 160°C and 400°C was investigated for impact Weber numbers between 20 and 170, taking side view images of impacting drops at a rate of 1,000 frames per second.

[EN] The impact morphology of dilute polymer solution drops on a heated surface is studied experimentally by means of high-speed imaging, with respect to the following parameters: surface temperature; impact Weber number; polymer concentration; polymer molecular weight. In addition to impact morphologies observed in Newtonian drops (deposition, rebound, secondary atomisation and breakup/splashing), three new impact regimes have been identified: (i) a single satellite droplet ejected in the direction of bouncing but tethered to the main drop by a thin liquid filament; (ii) a splashing-like behaviour (semi-splashing), where the rim instability generates satellite droplets tethered to the lamella by thin liquid filaments; (iii) a spray-like behaviour (semi-spray), where a fine secondary atomisation generated upon impact is quickly absorbed back into the drop globule. Experiments were carried out using drops of aqueous polyethylene oxide (PEO) solutions, with mass concentrations of 100 ppm, 200 ppm and 400 ppm, and PEO molecular weights of 2 MDa, 4MDa, and 8MDa. The impact morphology on a polished aluminium surface with temperatures ranging between 160°C and 400°C was investigated for impact Weber numbers between 20 and 170, taking side view images of impacting drops at a rate of 1,000 frames per second.

[EN] The impact morphology of dilute polymer solution drops on a heated surface is studied experimentally by means of high-speed imaging, with respect to the following parameters: surface temperature; impact Weber number; polymer concentration; polymer molecular weight. In addition to impact morphologies observed in Newtonian drops (deposition, rebound, secondary atomisation and breakup/splashing), three new impact regimes have been identified: (i) a single satellite droplet ejected in the direction of bouncing but tethered to the main drop by a thin liquid filament; (ii) a splashing-like behaviour (semi-splashing), where the rim instability generates satellite droplets tethered to the lamella by thin liquid filaments; (iii) a spray-like behaviour (semi-spray), where a fine secondary atomisation generated upon impact is quickly absorbed back into the drop globule. Experiments were carried out using drops of aqueous polyethylene oxide (PEO) solutions, with mass concentrations of 100 ppm, 200 ppm and 400 ppm, and PEO molecular weights of 2 MDa, 4MDa, and 8MDa. The impact morphology on a polished aluminium surface with temperatures ranging between 160°C and 400°C was investigated for impact Weber numbers between 20 and 170, taking side view images of impacting drops at a rate of 1,000 frames per second.

This work presents a study of the influence of the molecular weight on the thermodynamic modeling of the viscosity of non-newtonian polymer solutions. The employed model is based on the absolute rate theory of Eyring and on the solution theory of McMillan-Mayer. The Soave-Redlich-Kwong equation of state was adopted for the calculation of the excess molar McMillan-Mayer free energy derived from the osmotic pressure of the solution. The model presents parameters that take account separately the different possibilities of interaction in the macromolecular environment. As the tertiary structure of a polymer molecule can be affected by applied shear stress, only the parameters related with the intramolecular interactions are dependent of the shear stress. The experimental rheological curves for different molecular weights of polyethylene glycol aqueous solutions have been measured at several concentrations, within the whole polymer solubility range, at 298.15 K and 0.1 MPa. The dependence on the molecular weight for all parameters of the model was analyzed and characterized. The dependence of the shear sensitive parameters on the shear stress was also studied.

This paper studies the Rayleigh-Plateau instability for co-flowing immiscible aqueous polymer solutions in a microfluidic channel. Careful vibration-free experiments with controlled actuation of the flow allowed direct measurement of the growth rate of this instability. Experiments for the well-known aqueous two phase system (ATPS, or aqueous biphasic systems) of dextran and polyethylene glycol solutions exhibited a growth rate of 1 s-1, which was more than an order of magnitude slower than an analogous experiment with two immiscible Newtonian fluids with viscosities and interfacial tension that closely matched the ATPS experiment. Viscoelastic effects and adhesion to the walls were ruled out as explanations for the observed behavior. The results are remarkable because all current theory suggests that such dilute polymer solutions should break up faster, not slower, than the analogous Newtonian case. Microfluidic uses of aqueous two phase systems include separation of labile biomolecules but have hitherto be limited because of the difficulty in making droplets. The results of this work teach how to design devices for biological microfluidic ATPS platforms., ChemE/Chemical Engineering, Applied Sciences

This paper studies the Rayleigh-Plateau instability for co-flowing immiscible aqueous polymer solutions in a microfluidic channel. Careful vibration-free experiments with controlled actuation of the flow allowed direct measurement of the growth rate of this instability. Experiments for the well-known aqueous two phase system (ATPS, or aqueous biphasic systems) of dextran and polyethylene glycol solutions exhibited a growth rate of 1 s-1, which was more than an order of magnitude slower than an analogous experiment with two immiscible Newtonian fluids with viscosities and interfacial tension that closely matched the ATPS experiment. Viscoelastic effects and adhesion to the walls were ruled out as explanations for the observed behavior. The results are remarkable because all current theory suggests that such dilute polymer solutions should break up faster, not slower, than the analogous Newtonian case. Microfluidic uses of aqueous two phase systems include separation of labile biomolecules but have hitherto be limited because of the difficulty in making droplets. The results of this work teach how to design devices for biological microfluidic ATPS platforms., ChemE/Chemical Engineering, Applied Sciences

We consider statistical mechanical properties of the primitive chain network (PCN) model for entangled polymers from its dynamic equations. We show that the dynamic equation for the segment number of the PCN model does not reduce to the standard Langevin equation which satisfies the detailed balance condition. We propose heuristic modifications for the PCN dynamic equation for the segment number, to make it reduce to the standard Langevin equation. We analyse some equilibrium statistical properties of the modified PCN model, by using the effective free energy obtained from the modified PCN dynamic equations. The PCN effective free energy can be interpreted as the sum of the ideal Gaussian chain free energy and the repulsive interaction energy between slip-links. By using the single chain approximation, we calculate several distribution functions of the PCN model. The obtained distribution functions are qualitatively different from ones for the simple slip-link model without any direct interactions between slip-links.

Dai, Zhuojun., Thesis (M.Phil.)--Chinese University of Hong Kong, 2011., Includes bibliographical references., s in English and Chinese., 摘要 --- p.i, p.iii, ACKNOWLEDGEMENT --- p.v, Chapter Chapter 1 --- Introduction and Background --- p.-1, Chapter 1.1 --- General introduction to internal motions --- p.-1, Chapter 1.1.1 --- Definition of translational diffusion and internal motions --- p.-1, Chapter 1.1.2 --- Theoretical background of internal motions --- p.-1, Chapter 1.2 --- Investigation of internal motions on LLS --- p.-4, Chapter 1.2.1 --- General introduction on investigation of internal motion by LLS --- p.-4, Chapter 1.2.2 --- Theory on internal motion detected by LLS --- p.-5, Chapter 1.3 --- Laser light scattering --- p.-6, Chapter 1.3.1 --- General introduction to laser light scattering --- p.-6, Chapter 1.3.2 --- Data process about internal motions in LLS --- p.-9, Chapter 1.4 --- Notes and References --- p.-12, Chapter Chapter 2 --- Internal motions of PNIPAM chains in 6 and bad solvent --- p.-15, Chapter 2.1 --- Introduction --- p.-15, Chapter 2.2 --- Experimental section --- p.-15, Chapter 2.2.1 --- Sample preparation --- p.-15, Chapter 2.2.2 --- Dynamic laser light scattering --- p.-16, Chapter 2.3 --- Result and discussion --- p.-16, Chapter 2.4 --- Conclusion --- p.-23, Chapter 2.5 --- Notes and References --- p.-25, Chapter Chapter 3 --- Internal motions of PNIPAM microgels in 6 and bad solvent --- p.-26, Chapter 3.1 --- Introduction --- p.-26, Chapter 3.2 --- Experimental section --- p.-26, Chapter 3.2.1 --- Sample preparation --- p.-26, Chapter 3.2.2 --- Dynamic laser light scattering --- p.-21, Chapter 3.3 --- Result and discussion --- p.-27, Chapter 3.4 --- Conclusion --- p.-30, Chapter 3.5 --- Notes and References --- p.-31, Chapter Chapter 4 --- Examination on the internal motions variations with solvent quality of Polystyrene chains --- p.-32, Chapter 4.1 --- Introduction --- p.-32, Chapter 4.2 --- Experimental Section --- p.-32, Chapter 4.2.1 --- Sample preparation --- p.-32, Chapter 4.2.2 --- Dynamic laser light scattering --- p.-33, Chapter 4.3 --- Result and discussion --- p.-33, Chapter 4.4 --- Conclusion --- p.-36, Chapter 4.5 --- Notes and References --- p.-38, Chapter Chapter 5 --- Examination on the internal motions variations with solvent quality of Poly(methyl methacrylate) chains --- p.-40, Chapter 5.1 --- Introduction --- p.-40, Chapter 5.2 --- Experimental Section --- p.-40, Chapter 5.2.1 --- Sample preparation --- p.-40, Chapter 5.2.2 --- Dynamic laser light scattering --- p.-41, Chapter 5.3 --- Result and discussion --- p.-41, Chapter 5.4 --- Conclusion --- p.-45, Chapter 5.5 --- Notes and References --- p.-46, http://library.cuhk.edu.hk/record=b5894759, Use of this resource is governed by the terms and conditions of the Creative Commons “Attribution-NonCommercial-NoDerivatives 4.0 International” License (http://creativecommons.org/licenses/by-nc-nd/4.0/)

We develop a method of poroelastic relaxation indentation (PRI) to characterize thin layers of gels. The solution to the time-dependent boundary-value problem is obtained in a remarkably simple form, so that the force-relaxation curve obtained by indenting a gel readily determines all the poroelastic constants of the gel-the shear modulus, Poisson's ratio, and the effective diffusivity. The method is demonstrated with a layer of polydimethylsiloxane immersed in heptane., Published in Journal of Applied Physics, v110 n8 p086103/1-3, 2011.

Includes bibliographical references (leaves 66-73)., Includes abstract.

Includes bibliographical references (leaves 66-73)., Includes abstract.

This thesis describes a novel microfluidic platform to control the macromolecular concentrations and their applications in constructing the phase diagram of polymer aqueous solutions and in the high-throughput screening of protein crystallization conditions at the nanoliter scale. The microfluidic platform was fabricated using the soft-lithography method and based on poly(dimethylsiloxane) (PDMS) material, which is widely used in microfluidic device. PDMS is gas and water permeable elastomer. By exploiting the permeability of the gas and water in PDMS, we developed the degassed-PDMS nanoliter liquid dispensing system, the controlled microevaporation method in constructing the phase diagram of polymer aqueous solution, and the screening platform of protein crystallization conditions., This thesis describes two types of degassed-PDMS nanoliter liquid dispensing system. One is dispensing without the microvalve, in which various liquids are dispensed through the degassed PDMS microchannel. It involves two steps: in the first step, the PDMS microchannel patch (or the entire microchip) is placed in a vacuum chamber for a certain time; in the second step, the target liquid is deposited at the inlet of the PDMS channel and dispensed into the PDMS microchamber. The other method is dispensing with the aid of PDMS microvalve. This method combines the valve control and degassed PDMS pumping source, which provides more control over on the liquid dispensing, such as isolating, mixing, etc., Zhou, Xuechang., Adviser: Bo Zheng., Source: Dissertation Abstracts International, Volume: 72-04, Section: B, page: ., Thesis (Ph.D.)--Chinese University of Hong Kong, 2010., Includes bibliographical references (leaves 53-56)., Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web., Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web., also in Chinese., isbn: 9781124494142, Use of this resource is governed by the terms and conditions of the Creative Commons “Attribution-NonCommercial-NoDerivatives 4.0 International” License (http://creativecommons.org/licenses/by-nc-nd/4.0/)

This thesis describes a novel microfluidic platform to control the macromolecular concentrations and their applications in constructing the phase diagram of polymer aqueous solutions and in the high-throughput screening of protein crystallization conditions at the nanoliter scale. The microfluidic platform was fabricated using the soft-lithography method and based on poly(dimethylsiloxane) (PDMS) material, which is widely used in microfluidic device. PDMS is gas and water permeable elastomer. By exploiting the permeability of the gas and water in PDMS, we developed the degassed-PDMS nanoliter liquid dispensing system, the controlled microevaporation method in constructing the phase diagram of polymer aqueous solution, and the screening platform of protein crystallization conditions., This thesis describes two types of degassed-PDMS nanoliter liquid dispensing system. One is dispensing without the microvalve, in which various liquids are dispensed through the degassed PDMS microchannel. It involves two steps: in the first step, the PDMS microchannel patch (or the entire microchip) is placed in a vacuum chamber for a certain time; in the second step, the target liquid is deposited at the inlet of the PDMS channel and dispensed into the PDMS microchamber. The other method is dispensing with the aid of PDMS microvalve. This method combines the valve control and degassed PDMS pumping source, which provides more control over on the liquid dispensing, such as isolating, mixing, etc., Zhou, Xuechang., Adviser: Bo Zheng., Source: Dissertation Abstracts International, Volume: 72-04, Section: B, page: ., Thesis (Ph.D.)--Chinese University of Hong Kong, 2010., Includes bibliographical references (leaves 53-56)., Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web., Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web., also in Chinese., isbn: 9781124494142, Use of this resource is governed by the terms and conditions of the Creative Commons “Attribution-NonCommercial-NoDerivatives 4.0 International” License (http://creativecommons.org/licenses/by-nc-nd/4.0/)

In condensed polymeric liquids confined in slit channels, the movement of chains is constrained by two factors: entanglement among the chains and the excluded volume between the chains and the wall. In this study, we propose a wall boundary (WB) model for the primitive chain network (PCN) model, which describes the dynamics of polymer chains in bulk based on coarse graining upon the characteristic molecular weight of the entanglement. The proposed WB model is based on the assumptions that (i) polymers are not stuck but simply reflected randomly by the wall, and (ii) subchains below the entanglement length scale behave like those in bulk even near the wall. Using the WB model, we simulate the dynamics of entangled polymer chains confined in slit channels. The results show that as the slit narrows, the chains are compressed in the direction normal to the wall, while they are expanded in the parallel direction. In addition, the relaxation time of the end-to-end vector increases, and the diffusivity of the center of mass decreases. The compression in the normal direction is a natural effect of confinement, while the expansion is introduced by a hooking process near the wall. The trends revealed that the relaxation time and diffusivity depend on the increase in friction due to an increased number of entanglements near the wall, which is also associated with the hooking process in the PCN model. These results are expected within the assumptions of the PCN model. Thus, the proposed WB model can successfully reproduce the effects of wall confinement on chains.

In condensed polymeric liquids confined in slit channels, the movement of chains is constrained by two factors: entanglement among the chains and the excluded volume between the chains and the wall. In this study, we propose a wall boundary (WB) model for the primitive chain network (PCN) model, which describes the dynamics of polymer chains in bulk based on coarse graining upon the characteristic molecular weight of the entanglement. The proposed WB model is based on the assumptions that (i) polymers are not stuck but simply reflected randomly by the wall, and (ii) subchains below the entanglement length scale behave like those in bulk even near the wall. Using the WB model, we simulate the dynamics of entangled polymer chains confined in slit channels. The results show that as the slit narrows, the chains are compressed in the direction normal to the wall, while they are expanded in the parallel direction. In addition, the relaxation time of the end-to-end vector increases, and the diffusivity of the center of mass decreases. The compression in the normal direction is a natural effect of confinement, while the expansion is introduced by a hooking process near the wall. The trends revealed that the relaxation time and diffusivity depend on the increase in friction due to an increased number of entanglements near the wall, which is also associated with the hooking process in the PCN model. These results are expected within the assumptions of the PCN model. Thus, the proposed WB model can successfully reproduce the effects of wall confinement on chains.

We present an experimental demonstration of a method using optical tweezers proposed by Fischer and Berg-Sorensen for measuring viscoelasticity using optical tweezers. It is based on a sinusoidal oscillation of the liquid in combination with force measurements using optical tweezers. We verify the method by applying it to measurements in water, glycerol and polyethylene oxide (PEO)., QC 20141023

Polymer-induced drag reduction is the phenomenon by which the friction factor of a turbulent flow is reduced by the addition of small amounts of high-molecular-weight linear polymers, which conformation in solution at rest can vary between randomly coiled and rodlike. It is well known that drag reduction is positively correlated to viscous stresses, which are generated by extended polymers. Rodlike polymers always assume this favorable conformation, while randomly coiling chains need to be unraveled by fluid strain rate in order to become effective. The coiling and stretching of flexible polymers in turbulent flow produce an additional elastic component in the polymer stress. The effect of the elastic stresses on drag reduction is unclear. To study this issue, we compare direct numerical simulations of turbulent drag reduction in channel flow using constitutive equations describing solutions of rigid and flexible polymers. When compared at constant or2, both simulations predict the same amount of drag reduction. Here o is the polymer volume fraction and r is the polymer aspect ratio, which for flexible polymers is based on average polymer extension at the channel wall. This demonstrates that polymer elasticity plays a marginal role in the mechanism for drag reduction., Multi-Scale Physics, Applied Sciences

We discuss the thermal motion of colloidal particles in transient polymer networks. For particles that are physically bound to the surrounding chains, light-scattering experiments reveal that the submillisecond dynamics changes from diffusive to Rouse-like upon crossing the network formation threshold. Particles that are not bound do not show such a transition. At longer time scales the mean-square displacement (MSD) exhibits a caging plateau and, ultimately, a slow diffusive motion. The slow diffusion at longer time scales can be related to the macroscopic viscosity of the polymer solutions. Expressions that relate the caging plateau to the macroscopic network elasticity are found to fail for the cases presented here. The typical Rouse scaling of the MSD with the square root of time, as found in experiments at short time scales, is explained by developing a bead-spring model of a large colloidal particle connected to several polymer chains. The resulting analytical expressions for the MSD of the colloidal particle are shown to be consistent with experimental findings., DelftChemTech, Applied Sciences

Polymer-induced drag reduction is the phenomenon by which the friction factor of a turbulent flow is reduced by the addition of small amounts of high-molecular-weight linear polymers, which conformation in solution at rest can vary between randomly coiled and rodlike. It is well known that drag reduction is positively correlated to viscous stresses, which are generated by extended polymers. Rodlike polymers always assume this favorable conformation, while randomly coiling chains need to be unraveled by fluid strain rate in order to become effective. The coiling and stretching of flexible polymers in turbulent flow produce an additional elastic component in the polymer stress. The effect of the elastic stresses on drag reduction is unclear. To study this issue, we compare direct numerical simulations of turbulent drag reduction in channel flow using constitutive equations describing solutions of rigid and flexible polymers. When compared at constant or2, both simulations predict the same amount of drag reduction. Here o is the polymer volume fraction and r is the polymer aspect ratio, which for flexible polymers is based on average polymer extension at the channel wall. This demonstrates that polymer elasticity plays a marginal role in the mechanism for drag reduction., Multi-Scale Physics, Applied Sciences

We discuss the thermal motion of colloidal particles in transient polymer networks. For particles that are physically bound to the surrounding chains, light-scattering experiments reveal that the submillisecond dynamics changes from diffusive to Rouse-like upon crossing the network formation threshold. Particles that are not bound do not show such a transition. At longer time scales the mean-square displacement (MSD) exhibits a caging plateau and, ultimately, a slow diffusive motion. The slow diffusion at longer time scales can be related to the macroscopic viscosity of the polymer solutions. Expressions that relate the caging plateau to the macroscopic network elasticity are found to fail for the cases presented here. The typical Rouse scaling of the MSD with the square root of time, as found in experiments at short time scales, is explained by developing a bead-spring model of a large colloidal particle connected to several polymer chains. The resulting analytical expressions for the MSD of the colloidal particle are shown to be consistent with experimental findings., DelftChemTech, Applied Sciences

A systematic investigation by dielectric spectroscopy of 18 different water-rich mixtures with very different hydrophilic substances shows universal features for the water dynamics. The temperature dependence of the relaxation times exhibits a crossover from non-Arrhenius to Arrhenius behavior at the Tg range of the mixtures. Furthermore, the temperature dependence of the relaxation times presents a universal behavior both above and below the crossover temperature. We also show that these features suggest that the observed crossover is associated with the emergence of confinement effects.

Broadband dielectric spectroscopy and differential scanning calorimetry measurements have been performed to study the molecular dynamics poly (vinyl pyrrolidone) and its water solutions in a wide range of concentrations (0 wt %20 wt % suggesting that this dynamical process is dominated by water-water interactions. In addition, the temperature dependence of the water relaxation times exhibits a crossover from non-Arrhenius to Arrhenius behavior during cooling throughout the glass transition range, which has been interpreted as due to the constrains imposed by the rigid polymer matrix on the water molecules dynamics.

In Chapter 1, theories cited background of these studies as well as chemical synthesis methods used are introduced., In Chapter 2, theories of static and dynamic light scattering (LLS) as well as details of the LLS instrumentation are introduced, especially the application of LLS to polymer solutions., In Chapter 3, we present the study of the self-assembly of oligo( p-phenyteneethynylene)-based coil-rod-coil and rod-coil-rod triblock copolymers in the solvent mixture of toluene and hexane by using a combination of static and dynamic laser light scattering. UV-vis spectroscopy and fluorescence spectroscopy. Our results reveal that the aggregation in the solvent mixture is strongly influenced by the triblock copolymer structure. For the coil-rod-coil (PS-OPE-PS) triblock copolymer, small well-defined aggregates are formed in the solvent mixture with different toluene/hexane ratios. The coiled PS blocks entangle with the OPE block to restrict possible pi-pi stacking and make the OPE chain backbone more planar. The red-shift in the UV-vis and fluorescence spectra indicates the formation of 3-type aggregates. The rod-coil-rod (OPE-PS-OPE) triblock copolymer chains form large "disk-like" micelles with an ordered OPE core and a collapsed PS shell. The blue-shift in the UV-vis and fluorescence spectra shows the formation of H-type aggregates; namely, the OPE block in the core are parallel to each other so that there is stronger interchain pi-pi interaction., In Chapter 4, we present the study of the aggregation of C60-PEO-C 60 chains in the chloronaphthalene/benzene solvent mixture with different ratios by using a combination of static and dynamic laser light scattering. Chloronaphthalene is a good solvent for C60 but a poor solvent for the PEO chain. On the other hand, benzene is a good solvent for the PEO chain but a poor solvent for Co. Individual polymer chains or small micelles coexist with large aggregates in solvent mixture. Our results show that the structures of the aggregates strongly depend on the composition of the solvent mixtures, which reflects in different ratios of /, where and are z-average root-mean-square radius of gyration and hydrodynamic radius, respectively., In Chapter 5, we present a study of reversible formation and decomposition of star polymer clusters. First, we synthesized 4-aim bromide-end star polystyrene chains by using atom transfer radical polymerization (ATRP), and then modified the end group from bromide to thiol since it can be slowly oxidized in air to induce the clustering among 4-arm star polystyrene chains. The clustering is reversible under a reduction condition. Such formation and fragmentation (decomposition) of the polymer clusters in toluene was followed by LLS. To induce the reduction, DTT was added. Our results reveal that in the clustering, the fast mode is attributed to the cooperative diffusion of individual 4-arm star polystyrene chains (unimers), while the slow mode is related to the diffusion of large clusters. In the fragmentation, the slow mode becomes fast and its intensity contribution decreases as the reduction time increases, reflecting the decreases of the size and the number of large polymer clusters. Our results suggest that the clusters fragmentation induced by thiol-functionalized 4-PS chains in toluene dilute solution follows the universal RLCA regime, but in a reversed fashion., In this thesis, we did the following studies: (1) The association of two rod-coil triblock copolymers: polystyrene-oligo(p-phenyleneethynylene)-polystyrene (PS-OPE-PS) and oligo(p-phenyleneethynylene)-polystyrene-oligo( p-phenyleneethynylene) (OPE-PS-OPE) in a toluene/hexane mixture as well as of C60-Poly(ethylene oxide)-C60 in a chloronaphthalene/benzene mixture. (2) The formation and fragmentation of 4-arm-PS-SH cluster in toluene via the oxidization in air to form disulfide crosslink as well as the decomposition of the resultant cross-linked 4-arm star polystyrene clusters with reversible disulfide groups in toluene via reduction to thiol group by 2,3-dihydroxy-1,4-butanethiol (DTT)., Huo, Hong., "August 2007.", Adviser: Chi Wu., Source: Dissertation Abstracts International, Volume: 69-02, Section: B, page: 1037., Thesis (Ph.D.)--Chinese University of Hong Kong, 2007., Includes bibliographical references (p. 109)., Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web., Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web., in English and Chinese., School code: 1307., isbn: 9780549482130, Use of this resource is governed by the terms and conditions of the Creative Commons “Attribution-NonCommercial-NoDerivatives 4.0 International” License (http://creativecommons.org/licenses/by-nc-nd/4.0/)

In Chapter 1, theories cited background of these studies as well as chemical synthesis methods used are introduced., In Chapter 2, theories of static and dynamic light scattering (LLS) as well as details of the LLS instrumentation are introduced, especially the application of LLS to polymer solutions., In Chapter 3, we present the study of the self-assembly of oligo( p-phenyteneethynylene)-based coil-rod-coil and rod-coil-rod triblock copolymers in the solvent mixture of toluene and hexane by using a combination of static and dynamic laser light scattering. UV-vis spectroscopy and fluorescence spectroscopy. Our results reveal that the aggregation in the solvent mixture is strongly influenced by the triblock copolymer structure. For the coil-rod-coil (PS-OPE-PS) triblock copolymer, small well-defined aggregates are formed in the solvent mixture with different toluene/hexane ratios. The coiled PS blocks entangle with the OPE block to restrict possible pi-pi stacking and make the OPE chain backbone more planar. The red-shift in the UV-vis and fluorescence spectra indicates the formation of 3-type aggregates. The rod-coil-rod (OPE-PS-OPE) triblock copolymer chains form large "disk-like" micelles with an ordered OPE core and a collapsed PS shell. The blue-shift in the UV-vis and fluorescence spectra shows the formation of H-type aggregates; namely, the OPE block in the core are parallel to each other so that there is stronger interchain pi-pi interaction., In Chapter 4, we present the study of the aggregation of C60-PEO-C 60 chains in the chloronaphthalene/benzene solvent mixture with different ratios by using a combination of static and dynamic laser light scattering. Chloronaphthalene is a good solvent for C60 but a poor solvent for the PEO chain. On the other hand, benzene is a good solvent for the PEO chain but a poor solvent for Co. Individual polymer chains or small micelles coexist with large aggregates in solvent mixture. Our results show that the structures of the aggregates strongly depend on the composition of the solvent mixtures, which reflects in different ratios of /, where and are z-average root-mean-square radius of gyration and hydrodynamic radius, respectively., In Chapter 5, we present a study of reversible formation and decomposition of star polymer clusters. First, we synthesized 4-aim bromide-end star polystyrene chains by using atom transfer radical polymerization (ATRP), and then modified the end group from bromide to thiol since it can be slowly oxidized in air to induce the clustering among 4-arm star polystyrene chains. The clustering is reversible under a reduction condition. Such formation and fragmentation (decomposition) of the polymer clusters in toluene was followed by LLS. To induce the reduction, DTT was added. Our results reveal that in the clustering, the fast mode is attributed to the cooperative diffusion of individual 4-arm star polystyrene chains (unimers), while the slow mode is related to the diffusion of large clusters. In the fragmentation, the slow mode becomes fast and its intensity contribution decreases as the reduction time increases, reflecting the decreases of the size and the number of large polymer clusters. Our results suggest that the clusters fragmentation induced by thiol-functionalized 4-PS chains in toluene dilute solution follows the universal RLCA regime, but in a reversed fashion., In this thesis, we did the following studies: (1) The association of two rod-coil triblock copolymers: polystyrene-oligo(p-phenyleneethynylene)-polystyrene (PS-OPE-PS) and oligo(p-phenyleneethynylene)-polystyrene-oligo( p-phenyleneethynylene) (OPE-PS-OPE) in a toluene/hexane mixture as well as of C60-Poly(ethylene oxide)-C60 in a chloronaphthalene/benzene mixture. (2) The formation and fragmentation of 4-arm-PS-SH cluster in toluene via the oxidization in air to form disulfide crosslink as well as the decomposition of the resultant cross-linked 4-arm star polystyrene clusters with reversible disulfide groups in toluene via reduction to thiol group by 2,3-dihydroxy-1,4-butanethiol (DTT)., Huo, Hong., "August 2007.", Adviser: Chi Wu., Source: Dissertation Abstracts International, Volume: 69-02, Section: B, page: 1037., Thesis (Ph.D.)--Chinese University of Hong Kong, 2007., Includes bibliographical references (p. 109)., Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web., Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web., in English and Chinese., School code: 1307., isbn: 9780549482130, Use of this resource is governed by the terms and conditions of the Creative Commons “Attribution-NonCommercial-NoDerivatives 4.0 International” License (http://creativecommons.org/licenses/by-nc-nd/4.0/)

In this work, two "classical" (UNIFAC-FV, Entropic-FV) and two "recent" free-volume (FV) models (Kannan-FV, Freed-FV) are comparatively evaluated for polymer-solvent vapor-liquid equilibria including both aqueous and non-aqueous solutions. Moreover, some further developments are presented here to improve the performance of a recent model, the so-called Freed-FV First, we propose a modification of the Freed-FV model accounting for the anomalous free-volume behavior of aqueous systems (unlike the other solvents, water has a lower free-volume percentage than polymers). The results predicted by the modified Freed-FV model for athermal and non-athermal polymer systems are compared to other "recent" and "classical" FV models, indicating an improvement for the modified Freed-FV model for aqueous polymer solutions. Second, for the original Freed-FV model, new UNIFAC group energy parameters are regressed for aqueous and alcohol solutions, based on the physical values of the van der Waals volume and surface areas for both FV-combinatorial and residual contributions. The prediction results of both "recent" and "classical" FV models using the new regressed energy parameters are significantly better, compared to using the classical UNIFAC parameters, for VLE of aqueous and alcohol polymer systems.

In this work, two "classical" (UNIFAC-FV, Entropic-FV) and two "recent" free-volume (FV) models (Kannan-FV, Freed-FV) are comparatively evaluated for polymer-solvent vapor-liquid equilibria including both aqueous and non-aqueous solutions. Moreover, some further developments are presented here to improve the performance of a recent model, the so-called Freed-FV First, we propose a modification of the Freed-FV model accounting for the anomalous free-volume behavior of aqueous systems (unlike the other solvents, water has a lower free-volume percentage than polymers). The results predicted by the modified Freed-FV model for athermal and non-athermal polymer systems are compared to other "recent" and "classical" FV models, indicating an improvement for the modified Freed-FV model for aqueous polymer solutions. Second, for the original Freed-FV model, new UNIFAC group energy parameters are regressed for aqueous and alcohol solutions, based on the physical values of the van der Waals volume and surface areas for both FV-combinatorial and residual contributions. The prediction results of both "recent" and "classical" FV models using the new regressed energy parameters are significantly better, compared to using the classical UNIFAC parameters, for VLE of aqueous and alcohol polymer systems.

Thermosetting polymers can cure at a gradient of cure temperatures due to a variety of factors, including heat transfer in the thermoset during heating and the exotherm due to the chemical reaction occurring during the cure. A new method for assessing the effect of cure conditions on mechanical behavior of toughened thermosets has been developed. Modeling of the phase separation process of a model thermoset system provided detailed understanding of the mechanism of property variation with cure temperature for this material. Subsequent characterization of gradient temperature cured samples has shown important variations, illustrating not only the importance of cure conditions, but the possibility of producing materials with new and useful properties. A special mold was developed to cure samples in a controlled gradient of temperature. Example systems known to show pronounced variations in microstructure cured in this gradient mold showed large variations of microstructure as a function of position within the sample, corresponding to the cure temperature at that point. A model toughened thermoset system was developed to demonstrate gradients of properties following cure in the gradient temperature mold. Cyanate ester materials were modified with hydroxyl-terminated butadiene-acrylonitrile copolymers as well as low Tg amorphous polyesters. The polyesters showed very desirable properties for a toughener, including relatively good thermo-oxidative stability in comparison with the butadiene-acrylonitrile toughener. However, the variation of properties of the cured materials with temperature was small, and to better understand the property variation possible using a gradient cure temperature technique, the butadiene-acrylonitrile toughened cyanate ester system was chosen for further study. This system showed a significant variation of glass transition temperature of the cyanate-rich phase as a function of cure temperature. Modeling of the phase separation process of this m

These days leading oil and gas producing companies are investing increasing amounts of money into the development of non-fossil energy sources like wind-, solar-, biomass energy and forestry. On the other hand these companies are persisting in developing techniques to make energy recovery more efficient intending to stretch the life span of fossil resources. One of the more mature techniques to improve recovery efficiency is polymer flooding. Herein polymer solutions are injected in injector wells to pressurise producers thereby sweeping oil. The high viscosity attained by dissolving polymers in water makes oil displacement more efficient compared to conventional water injection. More generally, efficiency can be enhanced by reducing the water production, which is worldwide an increasing problem for operators. In mature oil fields, as oil depletion induces a rise in the oil-water contact, water breaks through in the production wells at a certain moment. Breakthrough can also result from stimulation by water injection. Depending on the specific situation water production can be decreased by shutting off the bottom of the well or plugging certain water producing layers by using polymer gels or cements, the so-called water shut-off treatments. Other shut-off treatments involve disproportionate permeability reducers (DPRs), which are usually polymer solutions. DPR working is based on the fact that adsorption of hydrophilic polymers can strongly decrease the permeability to water while having little effect on the permeability to oil. For an effective application of the above-mentioned technologies knowledge of polymer flow behaviour and retention behaviour, both in porous media, is indispensable. Apart from oil-related applications this field is important to many other industries and technologies, but nevertheless it is still not well understood. The main reason for this is the complex relationship between rheology and retention behaviour. Both are depending on porous me, Applied Sciences

Ngai To., "May 2003.", Thesis (Ph.D.)--Chinese University of Hong Kong, 2003., Includes bibliographical references., Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web., Mode of access: World Wide Web., s in English and Chinese., http://library.cuhk.edu.hk/record=b6073531, Use of this resource is governed by the terms and conditions of the Creative Commons “Attribution-NonCommercial-NoDerivatives 4.0 International” License (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Ngai To., "May 2003.", Thesis (Ph.D.)--Chinese University of Hong Kong, 2003., Includes bibliographical references., Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web., Mode of access: World Wide Web., s in English and Chinese., http://library.cuhk.edu.hk/record=b6073531, Use of this resource is governed by the terms and conditions of the Creative Commons “Attribution-NonCommercial-NoDerivatives 4.0 International” License (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Probability distributions for classical and quantum systems. Microcanonical, canonical, and grand canonical partition-functions and associated thermodynamic potentials. Conditions of thermodynamic equilibrium for homogenous and heterogenous systems. Applications: non-interacting Bose and Fermi gases; mean field theories for real gases, binary mixtures, magnetic systems, polymer solutions; phase and reaction equilibria, critical phenomena. Fluctuations, correlation functions and susceptibilities, and Kubo formulae. Evolution of distribution functions: Boltzmann and Smoluchowski equations.

These days leading oil and gas producing companies are investing increasing amounts of money into the development of non-fossil energy sources like wind-, solar-, biomass energy and forestry. On the other hand these companies are persisting in developing techniques to make energy recovery more efficient intending to stretch the life span of fossil resources. One of the more mature techniques to improve recovery efficiency is polymer flooding. Herein polymer solutions are injected in injector wells to pressurise producers thereby sweeping oil. The high viscosity attained by dissolving polymers in water makes oil displacement more efficient compared to conventional water injection. More generally, efficiency can be enhanced by reducing the water production, which is worldwide an increasing problem for operators. In mature oil fields, as oil depletion induces a rise in the oil-water contact, water breaks through in the production wells at a certain moment. Breakthrough can also result from stimulation by water injection. Depending on the specific situation water production can be decreased by shutting off the bottom of the well or plugging certain water producing layers by using polymer gels or cements, the so-called water shut-off treatments. Other shut-off treatments involve disproportionate permeability reducers (DPRs), which are usually polymer solutions. DPR working is based on the fact that adsorption of hydrophilic polymers can strongly decrease the permeability to water while having little effect on the permeability to oil. For an effective application of the above-mentioned technologies knowledge of polymer flow behaviour and retention behaviour, both in porous media, is indispensable. Apart from oil-related applications this field is important to many other industries and technologies, but nevertheless it is still not well understood. The main reason for this is the complex relationship between rheology and retention behaviour. Both are depending on porous me, Applied Sciences

Probability distributions for classical and quantum systems. Microcanonical, canonical, and grand canonical partition-functions and associated thermodynamic potentials. Conditions of thermodynamic equilibrium for homogenous and heterogenous systems. Applications: non-interacting Bose and Fermi gases; mean field theories for real gases, binary mixtures, magnetic systems, polymer solutions; phase and reaction equilibria, critical phenomena. Fluctuations, correlation functions and susceptibilities, and Kubo formulae. Evolution of distribution functions: Boltzmann and Smoluchowski equations.

by Niu Aizhen., "Mar., 2001.", Thesis (Ph.D.)--Chinese University of Hong Kong, 2001., Includes bibliographical references., Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web., Mode of access: World Wide Web., s in English and Chinese., http://library.cuhk.edu.hk/record=b6073484, Use of this resource is governed by the terms and conditions of the Creative Commons “Attribution-NonCommercial-NoDerivatives 4.0 International” License (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Peng Shufu., Thesis (Ph.D.)--Chinese University of Hong Kong, 2001., Includes bibliographical references., Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web., Mode of access: World Wide Web., s in English and Chinese., http://library.cuhk.edu.hk/record=b6073903, Use of this resource is governed by the terms and conditions of the Creative Commons “Attribution-NonCommercial-NoDerivatives 4.0 International” License (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Lau Chin Wa., Thesis (M.Phil.)--Chinese University of Hong Kong, 2001., Includes bibliographical references (leaves 77-78)., s in English and Chinese., p.i, Chinese Abstract --- p.ii, Acknowledgement --- p.iv, Contents --- p.v, Abbreviations --- p.viii, List of Figures --- p.xiv, List of Tables --- p.xviii, Chapter Chapter 1 --- Introduction --- p.1, Chapter Chapter 2 --- Basic Principle of Laser Light Scattering and Instrumentation --- p.7, Chapter 2.1 --- Static laser light scattering (Static LLS) --- p.8, Chapter 2.2 --- Dynamic laser light scattering (Dynamic LLS) --- p.9, Chapter 2.3 --- Calibration between translational diffusion coefficient D and molar mass M --- p.10, Chapter 2.3.1 --- Tranform G(D) to Molar Mass Distributionfw(M) --- p.10, Chapter 2.3.2 --- Calibration between D and M- Using a set of narrowly distributed standards --- p.12, Chapter 2.3.3 --- Calibration between D and M- Using two or more broadly distributed samples --- p.12, Chapter 2.4 --- Data Analysis --- p.14, Chapter 2.5 --- References --- p.16, Chapter Chapter 3 --- Experimental --- p.17, Chapter 3.1 --- Laser Light Scattering Instrumentation --- p.17, Chapter 3.1.1 --- Overview of laser light scattering spectrometer --- p.17, Chapter 3.1.2 --- Differential Refractometer --- p.18, Chapter 3.2 --- References --- p.21, Chapter Chapter 4 --- Thermally Sensitive and Biocompatible Poly(N-vinylcaprolactam): Synthesis and Characterization of High Molar Mass Linear Chains, Chapter 4.1 --- Introduction --- p.22, Chapter 4.2 --- Sample Preparation --- p.23, Chapter 4.3 --- Results and discussion --- p.24, Chapter 4.4 --- Conclusion --- p.27, Chapter 4.5 --- References --- p.29, Chapter Chapter 5 --- Stabilization and destabilization of potassium persulfate (as an initiator) in an surfactant-free water/acetone mixture emulsion polymerization of styrene under microwave irradiation, Chapter 5.1 --- Introduction --- p.41, Chapter 5.2 --- Experimental --- p.43, Chapter 5.3 --- Results and discussion --- p.44, Chapter 5.4 --- Conclusion --- p.51, Chapter 5.5 --- References --- p.53, Appendix, Chapter A.l --- Static Laser Light Scattering --- p.66, Chapter A.1.1 --- Scattering from a small particles --- p.66, Chapter A.1.2 --- Scattering from a large particles --- p.67, Chapter A.1.3 --- Scattering by solutions of small molecules --- p.69, Chapter A.1.3.1 --- Scattering from polymer solutions --- p.70, Chapter A.2 --- Dynamic laser light scattering --- p.71, Chapter A.2.1 --- Line-width measurement --- p.73, Chapter A.2.2 --- Data analysis --- p.75, http://library.cuhk.edu.hk/record=b5890650, Use of this resource is governed by the terms and conditions of the Creative Commons “Attribution-NonCommercial-NoDerivatives 4.0 International” License (http://creativecommons.org/licenses/by-nc-nd/4.0/)