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Synthetically straightforward conditions have been developed for the preparation of poly(bis 2,2,2-trifluoroethoxy)- phosphazene with low PDI (

Linear poly(ethylenimine) is a cationic polymer that is actively being progressed into clinical trials for gene therapy. The existing synthetic methodology produces a relatively broad distribution of molecular weights. We describe an improved method of polymerizing 2-alkyl-2-oxazolines as a route to linear poly(ethylenimine). By using an apolar noninterfering solvent (chlorobenzene) at low temperature (∼42 °C), the polymerization of 2-isopropyl-2-oxazoline proceeds much more rapidly than is observed in acetonitrile, and with far fewer side reactions. 1H NMR observations showed close ion pairing at the propagating center (vice free ions in acetonitrile) to form a propagating complex of greater reactivity than free oxazolinium ions. Our results indicate that uniform or near uniform (“monodisperse”) polymers can be synthesized with nominal deviation from the theoretically achievable Poisson distributions.

Poly(ethylene glycol) [1, PEG(similar to 4)(OH)2, M-n similar to 2001, glycerol ethoxylate [2, PEG(similar to 21)(OH)3, M-n similar to 1000] and pentaerythritol ethoxylate [3, PEG(similar to 15)(OH)(4), M-n similar to 797] react directly with phenyl-C-61-butyric acid methyl ester (PCBM), in the presence of dibutyltinoxide (DBTO) catalyst at 140 degrees C, to give a mixture of fullerene [C-60] end-capped PEGs via transesterification. Among these PEG linkers, only PEG(similar to 4)(OPCB)(2) (4a) (OPCB: ester oxygen linked phenyl-C-61-butyryl group) was successfully isolated from the crude product mixture in the fully end-capped form. Fully acylated PEG(similar to 21)(OPCB)(3) (5) and PEG(similar to 15)(OPCB)(4) (6) could not be separated chromatographically from incompletely reacted species due to the polydispersity in branch lengths. This purification challenge was overcome by using a monodisperse branched core, 1,3,5-tris-(Octagoloxymethyl)benzene [7, PEG(24)(OH)(3)] to give a monodisperse tris-fullerene homostar, PEG(24)(OPCB)(3) (8). The structures of the bis- and tris-fullerene products were confirmed by MALDI-TOF mass spectrometry and H-1 NMR spectroscopy with supporting FTIR and UV-vis spectroscopic analysis.

Organic electronics requires dielectrics which can be processed over large areas at low temperature in ambient using simple solution based techniques. Here a crosslinkable acrylate‐based organic dielectric is reported, which is gravure printable on plastic substrates, patternable by conventional photolithography, and can form electrically functional films at thicknesses below 100 nm. Capacitors are successfully fabricated with film thicknesses of 50 and 70 nm, and organic field effect transistors with thicknesses of 70 nm, transistors with gold contacts patterned by lift‐off on top of the dielectric followed by spin‐cast 6,13‐bis(triisopropylsilylethynyl)‐pentacene showing near ideal behavior at operating voltages as low as −1 V. Importantly saturation, a requirement for digital logic, in transistors is achieved with gate lengths of 2.7 µm, at the limit of conventional photolithography. This demonstrates that such materials have potential in flexible organic electronic devices requiring digital signal processing and low voltages.

In order to develop inks suitable for roll-to-roll printing processes, which can be cured into in situ electrolyte filled high porosity macroporous polymer membranes, non-aqueous high internal phase emulsions (HIPEs) were prepared. The external phase of the formulated HIPEs consisted of lauryl methacrylate (LMA) and 1,14-tetradecanediol dimethacrylate (TDDMA) while a solution of bis(trifluoromethane)sulfonimide lithium salt (LiTFSI) in a mixture of ethylene (EC) and propylene carbonate (PC) served as the internal phase. The stability of these non-aqueous HIPEs was strongly affected by the surfactant and the LiTFSI concentration in the internal phase. HIPE templates could only be polymerised when the LiTFSI concentration varied between 0.06 and 0.8 mol l−1. Electrochemical, thermal properties as well as morphology of the resulting polyHIPEs are discussed with respect to HIPE composition. The ionic conductivity of the resulting polyHIPEs was measured to be in the range from 4.18 to 8.64 mS cm−1.

This paper presents the development of multifunctional materials that perform a structural role whilst simultaneously storing electrical energy as a supercapacitor. Two structural carbon fibre woven electrodes were separated by a woven glass fibre layer, and infused with a multifunctional polymer electrolyte. Following characterisation of electrochemical and compressive performance, working structural supercapacitor prototypes were demonstrated. Since the relative mechanical and electrical demands are application specific, an optimisation methodology is proposed. Multifunctional composites were achieved, which had compressive moduli of up to 39 GPa and capacitances of up to 52 mF g −1 .

The mechanism of polycation cytotoxicity and the relationship to polymer molecular weight is poorly understood. To gain an insight into this important phenomenon a range of newly synthesised uniform (near monodisperse) linear polyethylenimines, commercially available poly(L-lysine)s and two commonly used PEI -based transfectants (broad 22 kDa linear and 25 kDa branched) were tested for their cytotoxicity against the A549 human lung carcinoma cell line. Cell membrane damage assays (LDH release) and cell viability assays (MTT) showed a strong relationship to dose and polymer molecular weight, and increasing incubation times revealed that even supposedly "non-toxic" low molecular weight polymers still damage cell membranes. The newly proposed mechanism of cell membrane damage is acid catalysed hydrolysis of lipidic phosphoester bonds, which was supported by observations of the hydrolysis of DOPC liposomes. Crown Copyright (C) 2017 Published by Elsevier B.V. All rights reserved.

A series of methacrylate-crosslinked polymers were investigated as potential polymer electrolytes for energy storage application. Methacrylate ester crosslinkers (25–50 mol.%) with different spacer lengths and MMA as comonomer were polymerised into thin films. Mixtures of ethylene carbonate and propylene carbonate (EC/PC) or alternatively the ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIM TFSI), both doped with lithium bis(trifluoromethane)sulfonimide (LiTFSI), fulfilled the role of electrolyte and porogen simultaneously. Ionic conductivity increased with increasing porogen content, Li ion concentration, and decreasing amounts of crosslinker (maximum values: 0.5 mS/cm (EC/PC) and 4.5 mS/cm (EMIM TFSI)). Thin films with permanent porosity were obtained for both electrolyte systems. The flexibility of the films increased with a lower concentration of crosslinker or the choice of a crosslinker with a longer spacer. The relationship between pore size, pore morphology, glass transition temperature and ionic conductivity on the other hand was complex and did not exhibit distinct trends. High thermal stability, ionic conductivity and tunable mechanical properties make these polymer thin films attractive candidates as in situ filled Li ion battery separator films either preformed or directly printed.

A versatile method to prepare non-covalently crosslinked polyHIPEs hydrogels from oil-in-water high internal phase emulsions (HIPEs) whose aqueous phase contained thermo-responsive linear polymers is described. The interconnected pore structure of the polyHIPEs is maintained by reversible physical aggregation of thermo-responsive polymer chains in an aqueous environment. This method to prepare interconnected porous hydrogels using a thermal trigger in the guise of thermo-responsive polymers by emulsion templating requires no chemical reaction during solidification of the template. This particular feature could provide a safer route to injectable scaffolds as issues of polymerisation/crosslinking chemistry and residual initiator fragments or monomers do not arise.

Stable high internal phase emulsions (HIPEs) with the ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethyl-sulfonyl)imide as dispersed phase were prepared and polymerised thermally into polyHIPEs. All polyHIPEs exhibited pore morphologies similar to that of polyHIPEs obtained with an aqueous dispersed phase. PolyHIPEs containing the dispersed phase possess a low T(g) and are thermally stable in excess of 200 °C, offering the potential for new porous materials where water as dispersed phase is chemically or physically undesirable.

In recent years genetic modification of cells has promised to revolutionize medicine by offering novel therapeutic approaches in a range of diseases. However, lack of effective means of delivery has so far limited therapeutic applications. Polymeric vectors have been a much-investigated area of non-viral gene delivery but until recently the focus has been on plasmid DNA (pDNA) delivery. Current research suggests that polymer-mediated siRNA delivery is gaining momentum. Previous work in our group has resulted in an effective non-cytotoxic alternative to PEI for pDNA delivery in the lungs, using the reductive environment of the cytoplasm as a means of triggering polymer degradation. Here we present a review covering delivery of either pDNA or siRNA to the lungs, using different polymers. We critically review the key structural polymer characteristics for efficient gene lung delivery. We conclude that for highly efficient pulmonary gene delivery, non-toxic, bioresponsive polymers are required transfer the nucleic acid and genetically modify the lung tissue.

Hydrogels are prepared through free radical copolymerization of MAA and DMAEMA employing only non-covalent interactions. The formation of hydrogels is dependent on pH as well as copolymer composition as a consequence of balance of predominantly attractive and repulsive ionic interactions and hydrogen bonding. The hydrogels are stable between pH 3 and 8 and for MAA to DMAEMA ratios of 62:38 to 68:32. Elastic and loss moduli are characterized as a function of pH. Hydrogels can reform from swollen microgel particles and offer the opportunity of recyclability. In model experiments it is shown that the fl ow through porous media can be controlled by varying the pH, which offers new possibilities such as controlling the supply of growth factors in tissue engineering scaffolds or as degradable fl uid loss control agents for enhanced oil recovery.

Poly(vinyl ether) gels SLURPS (Superior Liquid Uptake Resin for Polymer-supported synthesis) with low cross-linking levels have been synthesized for the first time in beaded form using a non-aqueous inverse suspension polymerisation approach. The synthetic protocol was optimized with regards to several parameters including reactions conditions, type and concentration of suspension stabilizer and controlled low temperature addition of co-initiator. Particle size measurements confirm the production of beads with average diameters of 700e950 mm. Optimization of the monomer composition of the poly (vinyl ether) gels resulted in a novel beaded polymer support with considerably improved as well as unique swelling characteristics in solvents ranging from hexane to water. The synthetic utility of the new gel was confirmed by carrying out a set of transformations with complete conversion leading to a useful amino and hydroxy terminated solid-phase precursor resin. Reaction progress could be monitored easily by 1 H and 13C gel-phase NMR

Spiral-wound modules of solvent stable integrally skinned asymmetric nanofiltration membranes made from polyaniline (PANI) are reported. PANI membranes were made by phase inversion and crosslinked by chemical and thermal processes. In the chemical crosslinking process, PANI membrane cast on polypropylene non-woven backing was crosslinked using glutaraldehyde, and a 1.8 in. spiral-wound module was prepared. To crosslink membranes thermally, a 1.8 in. spiral-wound membrane module prepared from PANI membrane cast on polyester non-woven backing was heated at 180 °C for 2 h. The resultant membranes and modules were found to be stable in various organic solvents including acetone, tetrahydrofuran and N,N -dimethyl formamide. Filtrations carried out in acetone, tetrahydrofuran and dimethyl formamide gave stable permeate fluxes and good separation performances in the nanofiltration range. Molecular weight cut-off (MWCO) of the membranes was dependent on the nature of the solvent and temperature. MWCO of PANI membranes in different solvents was found to lie between 150 and 300 g mol −1 at 30 °C. The membranes were also found to be stable for operations at elevated temperatures up to 65 °C and possibly higher. These membranes retain their nanofiltration properties even after drying so the use of conditioning or preservative agents can be avoided.

The mass production technique of gravure contact printing is used to fabricate state-of-the art polymer field-effect transistors (FETs). Using plastic substrates with prepatterned indium tin oxide source and drain contacts as required for display applications, four different layers are sequentially gravure-printed: the semiconductor poly(3-hexylthiophene-2,5-diyl) (P3HT), two insulator layers, and an Ag gate. A crosslinkable insulator and an Ag ink are developed which are both printable and highly robust. Printing in ambient and using this bottom-contact/top-gate geometry, an on/off ratio of 10 4 and a mobility of 0.04cm 2 V -1 s -1 are achieved. This rivals the best top-gate polymer FETs fabricated with these materials. Printing using low concentration, low viscosity ink formulations, and different P3HT molecular weights is demonstrated. The printing speed of 40 m min -1 on a flexible polymer substrate demonstrates that very high-volume, reel-to-reel production of organic electronic devices is possible.

We report on studies of poly-(2,5-dihexyloxy-p-phenylenevinylene) (PDHeOPV), a symmetric side-chain polymer, as a potential new donor material for polymer:fullerene blend solar cells. We study the surface morphology of blend films of PDHeOPV with PCBM, the transport properties of the blend films, and the performance of photovoltaic devices made from such blend films, all as a function of PCBM content. In each case, results are compared with those obtained using the asymmetric side chain polymer, poly[2-methoxy-5-(3,7-dimethyloctyloxy)-1,4-phenylenevinylene] (MDMO-PPV), in order to investigate the influence of polymer side chain symmetry on solar cell performance. AFM images show that large PCBM aggregates appear at lower PCBM content (50 wt.% PCBM) for PDHeOPV:PCBM than for MDMO-PPV:PCBM (67 wt.% PCBM) blend films. Time-of-Flight (ToF) mobility measurements show that charge mobilities depend more weakly on PCBM content in PDHeOPV:PCBM than in MDMO:PPV:PCBM, with the result that at high PCBM content the mobilities in PDHeOPV:PCBM are significantly lower than in MDMO:PPV:PCBM blend films, despite the higher mobilities in pristine PDHeOPV compared to pristine MDMO-PPV. Photovoltaic devices show significantly lower power conversion efficiency (∼0.93%) for PDHeOPV:PCBM (80 wt.% PCBM) blend films than for MDMO-PPV:PCBM (2.2% at 80 wt.% PCBM) blends. This is attributed to the relatively poor transport properties of the PDHeOPV:PCBM blend, which limit the optimum thickness of the photoactive layer in PDHeOPV:PCBM blend devices. The behaviour is tentatively attributed to a higher tendency for the symmetric side-chain polymer chains to aggregate, resulting in poorer interaction with the fullerene and poorer network formation for charge transport.

A new family of functional materials is reported for organic solvent nanofiltration, with excellent chemical stability and high retention of solute molecules. Integrally skinned asymmetric polyaniline (PANI) membranes were fabricated from concentrated solutions of doped PANI by phase inversion. Doped PANI solutions were prepared by adding organic acids directly to PANI dissolved in a mixture of NMP and 4-methyl piperidine before casting. Among the organic acids investigated, maleic acid, phthalic acid, sulfosalicylic acid and camphorsulfonic acid were able to dope PANI without causing gelation. These acids acted as soft templates, creating nanoporosity in the thin skin layer of the asymmetric PANI film. Their removal by alkaline extraction created membranes through which small solvent molecules can pass. After extracting the organic acids, the membranes were thermally crosslinked which conferred excellent solvent stability. These membranes had a molecular weight cut-off (MWCO) in the range of 150–250 g mol−1 in methanol, making them the tightest OSN membranes reported to date. It was found that an increase in crosslinking temperature or time led to a decrease in solvent flux. PANI membranes were found to be resistant to a variety of organic solvents such as ethyl acetate, acetonitrile and acetone. These remarkable membranes have the potential to be used in OSN operations at high temperatures (up to 150 °C), and gave increasing fluxes with increasing temperature while maintaining a high solute rejection.

Solvent stable integrally skinned asymmetric nanofiltration membranes were prepared from polyaniline. These membranes were made by phase inversion and then crosslinked using two different chemical crosslinkers, α,α′-dichloro- p -xylene and glutaraldehyde. The resultant membranes were found to be stable in various organic solvents including acetone, methanol, ethyl acetate, tetrahydrofuran and N , N -dimethyl formamide. Nanofiltration experiments carried out in acetone and dimethyl formamide showed that the membranes gave stable permeate fluxes and good separation performances in the nanofiltration range. Molecular weight cut-off (MWCO) of the membranes was found to be between 150 and 250 g mol −1 . These membranes were also found to be stable for operations at elevated temperatures up to 70 °C and possibly higher. Furthermore, no fillers or preservative agents are required to maintain the membranes in a dry state thereby increasing the ease of handling.

Here we present the synthesis and characterization of pH responsive polyacrylamide microgels, synthesized via free radical polymerization of acrylamide and bis (acryloylcystamine) (BAC). The gels were made with ultralow amounts of thiol functional groups incorporated into the polymer. The resulting gel monoliths were mechanically chopped into microgel particles with size distributions ranging from 80 to 200 mum. The gels exhibit an interesting reversible pH-dependent rheological behavior which led to gelling of the colloidal suspension when the pH was increased, and a low-viscosity suspension was obtained when the pH was taken back to the original value. The viscosity of the colloidal system containing MBA crosslinked microgels remained insensitive to pH. This observation motivated further analysis; viscosity measurements of the highly viscous (gel-like) state of the BAC crosslinked microgel colloidal suspension were carried out to further understand the rheological behavior of the colloidal system. Electrophoretic mobility measurements as function of pH of the BAC and MBA crosslinked colloidal polyacrylamide microgel suspensions were performed. The swelling behavior of the microgels for both colloidal systems was also determined as function of pH using static light scattering. This swelling behavior was used to rationalize the observed rheological behavior. The work presented here demonstrates that free thiol groups present within a polymer gel matrix confer pH responsive behavior to the gel in solution. The viscosity of a BAC crosslinked microgel suspension was also measured under reducing conditions. The viscosity of the microgel suspension reduced with time, due to the breakage of the disulfide bonds in the crosslinkers.

A systematic study of the ruthenium-catalysed metathesis of alkenes containing hydrogen-bonding substituents (namely urea and thiourea groups) is presented. Under standard metathesis conditions, several of the substrates under study undergo alkene isomerisation instead of the targeted metathesis. However, in the course of these investigations it has been established that this unwanted isomerisation process can be suppressed by addition of phenylphosphoric acid to the reaction mixture. Some other potential isomerisation inhibitors (e.g. benzoic acid and salts of phosphoric acid) have been studied and their performance compared to that of phenylphosphoric acid. To extend the scope of phenylphosphoric acid, we also studied the metathesis of 1,3-diallylurea. Interestingly, not only did we observe the complete suppression of the isomerisation process, but also that it is possible to obtain instead of the ring-closing metathesis (RCM) product,ADMET oligomers resulting from the cross-metathesis of diallylurea at higher concentrations. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Sonicating pure N-methyl pyrrolidone (NMP) rapidly produces contaminating organic nanoparticles, at increasing concentration with time, as investigated by AFM, as well as UV-vis, IR and NMR spectroscopies. The contamination issue affects carbon nanotube, and likely other nanomaterial, dispersions processed by sonication in organic solvents.

Organic complementary circuitry combines all the advantages of plastic electronics, such as flexibility, thinness, and solution processability with low power consumption. Here, we report organic complimentary inverters fabricated in a carrier-free batch process on a plastic foil with dielectric and semiconductor layers patterned using the high-volume gravure contact printing technique. The transistor components have bottom-gate, bottom-contact configuration with aluminum gates and gold contacts, allowing full use of photolithographic processing while protecting the semiconductors by depositing them last. Cross-linkable polymer dielectric, p-type small molecule and n-type polymer semiconductors are printed from inks based on nonchlorinated solvents. Printing instability is observed for capillary numbers approaching 1. The 430-nm-thick dielectric affords a relatively low operational voltage, and it is the thinnest printed organic dielectric reported in the literature for organic inverters to date. Both p- and n-type transistors have a mobility of 0.01–0.04 cm $^{2}\text{V}^{\mathrm {-1}}\text{s}^{\mathrm {-1}}$ . The device parameters for the n-type transistors show less variation than the p-type transistors, which can be related to the more isotropic charge transport in polymer films compared with the small-molecule polycrystalline films. The resultant inverters have an average gain of 4.5 ± 1.5 and a maximum gain of 8 at $V_{\mathrm {DD}} =-20$ V. The combination of the conventional photolithographic processing and gravure contact printing can therefore be used to fabricate bottom-gate organic complementary circuitry on plastic.

Multifunctional composites which can fulfil more than one role within a system have attracted considerable interest. This work focusses on structural supercapacitors which simultaneously carry mechanical load whilst storing/delivering electrical energy. Critical mechanical properties (in-plane shear and in-plane compression performance) of two monofunctional and four multifunctional materials were characterised, which gave an insight into the relationships between these properties, the microstructures and fracture processes. The reinforcements included baseline T300 fabric, which was then either grafted or sized with carbon nanotubes, whilst the baseline matrix was MTM57, which was blended with ionic liquid and lithium salt (two concentrations) to imbue multifunctionality. The resulting composites exhibited a high degree of matrix heterogeneity, with the ionic liquid phase preferentially forming at the fibres, resulting in poor matrix-dominated properties. However, fibre-dominated properties were not depressed. Thus, it was demonstrated that these materials can now offer weight savings over conventional monofunctional systems when under modest loading.

The processing of complex nanoscale electronic structures on plastic substrates is a significant challenge, requiring the combination of low temperature, nonaggressive, and high resolution methods. Here a scalable process flow on plastic is presented tbat enables the fabrication of flexible nano­imprinted organic field-effect transistors (OFETs) with self-aligned contacts and solution-processed semiconductor and dielectric layers, at processing temperatures ≤ 150 °C. OFETs are fabricated with device cutoff frequencies f > 1 MHz at low operating bias V DS = −15 V. The technique allows the patterning of metal structures over four orders of magnitude from 375 nm to 1 mm without the need for a rigid carrier, and provides a fabrication pathway to high performance nanostructured organic circuitry.

In this paper, a simple demonstration is presented on the analysis of the combined effect of polymer chemistry and the polymerisation reactor on the polymer properties. The model would ideally account for the raw material and end-product characteristics and properties on the one hand; the polymerisation kinetics and reaction engineering on the other hand. This system-wide model-driven approach enables the interlinking of the widely disparate facets of polymer science and engineering, and thereby provides a tool for rapid and efficient identification and scale-up of new polymeric materials that would be exploited in future studies. The ideas are demonstrated with regard to a hyper-branched polymerisation chemistry.

Multi-functional monomer induced hyperbranched PMMA production has been shown to be a relatively facile, one-step batch solution polymerisation reaction. Essentially, the reaction is a linear polymerisation doped with appropriate amounts of multi-functional monomer (MFM) and chain transfer agent (CTA). A theoretical model for the MFM reaction has been experimentally validated using conversion, number-average molecular weight, and branching data, by employing key reaction parameters from established linear PMMA kinetics. However, the kinetic model has been modified to account for the MFM and CTA contributions, which generate the branched architecture and inhibit the onset of gelation, respectively. An important outcome of this work is the development of a generic model for hyperbranched polymer synthesis, in which the manufacture of other free-radical hyperbranched polymers, of desired architecture or physical properties, can be guided using modelling and optimisation methods. © 2005 Elsevier Ltd. All rights reserved.

This study reports the syntheses of aliphatic polyethers, by cationic ring-opening photo polymerisation of oxetane functionalised polypropylene glycol (PPG), and the application of these polyethers in forming membranes for use in the membrane aromatic recovery system (MARS). The PPG was functionalised using 3-methyl-3-bromomethyl oxetane. The cationic ring-opening polymerisation of oxetane functionalised PPG was effected by UV light in the presence of onium salt photoinitiator to produce crosslinked gels. This is the first study reporting the photo-initiated cationic ring-opening polymerisation of PPG. The polyethers produced showed high affinity for phenol (partition coefficient of 58 between polyether and water) and proved chemically stable in 10 wt.% caustic solution. The membranes were prepared by impregnating the mixture of oxetane functionalised PPG and onium salt photoinitiator into the pores of a mesoporous polypropylene support and subsequently exposing them to UV light. The membrane prepared was then tested under MARS operating conditions for more than 2 months during which it was observed to be stable. The membrane exhibited mass transfer rates (3 × 10 −6 m s −1 ) 20 times higher than that of tubular silicone rubber membranes (1.5 × 10 −7 m s −1 ).

The free radical synthesis of hyperbranched polymer architectures using a thermally and photochemically labile styrenic Barton ester monomer of the AB type, designed to combine the functions of initiator, monomer, and branch unit, is described. Highly branched poly(styrene)s were obtained in one step by copolymerizing this monomer with styrene. Residual Barton ester functionality in the hyperbranched products enabled their use as macroinitiators in subsequent polymerizations. Linear PMMA was thus successfully grafted from the hyperbranched poly(styrene) cores. This approach is a versatile route for the synthesis of hyperbranched homopolymers and copolymers via free radical polymerization chemistry.

This study reports the stabilization of supported liquid membranes, through cross-linking the liquid membrane phase by using γ-radiation, and the performance of the resulting membranes under Membrane Aromatic Recovery System (MARS) operating conditions. The membranes were prepared by impregnating polypropylene glycol (PPG) into the pores of microporous flat sheet membranes [polyvinylidene fluoride (PVDF) or polypropylene (PP)] and subsequently exposing them to γ-radiation. The membranes prepared exhibited operational stability when investigated under MARS operating conditions for more than 1 month. The PP (0.05 mm) membrane provided the best combination of high phenol mass transfer rates and low water flux for the MARS process among the membranes tested in this study. The phenol mass transfer rate through this membrane (27 x 10 -7 m s -1 ) was 18 times higher than that of silicone rubber tubing (1.5 x 10 -7 m s -1 ). This study also reports the effect of radiation dose on the mass transfer rates and on the membrane support itself.

Conformational characteristics of poly(ethylene imine) (PEI) have been investigated by a rotational isomeric state (RIS) analysis of ab initio molecular orbital (MO) calculations and 1H and 13C NMR experiments for a monomeric model compound, N,N‘-dimethylethylenediamine (di-MEDA). From the MO and NMR data, it was shown that the C−C and C−N bonds of di-MEDA have high gauche (71−93%) and trans (64−86%) preferences, respectively. Conformational energies of PEI were determined from the MO calculations for di-MEDA at the MP2/6-311++G(3df, 3pd)//HF/6-31G(d) level. The high gauche stability in the C−C bond was indicated to stem from a moderate and a weak intramolecular N−H···N hydrogen bonds; the interaction energies were evaluated as −1.54 and −0.58 kcal mol-1, respectively. The RIS scheme including rotational and inversional isomerizations was developed and applied to PEI to evaluate the chain dimension and diad probabilities. With the conformational energies determined as above, the characteristic ratio and m...

Emulsion polymerizations of methyl methacrylate were carried out in a pilot-scale tubular reactor configured in a batch-loop mode. The tubular sections of the reactor were fitted with in-line static mixers to incite low-shear mixing. The reactor was used to investigate the influence of different recipes and operating conditions on reaction, particularly on the monomer conversion and the polymer particle-size distribution. Experimental data were compared to equivalent bench-scale studies using a conventional stirred flask. A mathematical model was also developed for predicting the temperature dynamics and the conversion of methyl methacrylate polymerization in the pilot-scale reactor. Conversions and particle-size distributions of the pilot-scale loop reactor were found to be very similar to that of the bench-scale studies. The results indicate that in-line static mixers can help to maintain emulsion stability and provide a means for good temperature control, without unduly influencing polymer particle-size distribution. © 2005 American Chemical Society.

The key factors that control the performance of perfluorinated sulfonic acid polymer electrolyte membranes cannot be deeply understood without a structural model of the material. Models of different complexity have been discussed in the literature. In this paper, we suggest a more detailed structural model of Nafion-type membranes, which results from a combined analysis of the ionomer molecular structure, data on swelling, small-angle diffraction, and conductivity as a function of water content. The analysis focuses on geometrical constraints on the self-organization of the polymer and possible patterns of phase segregation within it. The model identifies the percolation bottlenecks for proton transport and resolves controversies about the water-content dependence of the activation energy of proton mobility. It also suggests a new framework for molecular dynamics simulations of proton and water transport in such media.

Stereoselective molecularly imprinted polymers (MIPs) have been synthesised via ring-opening metathesis polymerisation, in essentially, quantitative yield. A covalent imprinting strategy was followed during the network formation of the chiral sorbent. Recognition of the substrate however involved non-covalent interactions; a combination of hydrogen bonding and the chiral environment presented by the imprinted cavities. The enantiomeric excess achievable with these new MIPs is solvent dependent and stereoselectivities of up to 20% e.e. (separation factor α =2.2) were found in batch equilibrations.

Main chain and branched polyrotaxanes have been synthesized in which polymerization and rotaxane formation occur simultaneously, due to the presence of the catalytically active self-threading macrocycle cucurbit[6]uril. Using monomers that contain stopper groups to prevent the catalytic macrocycle from noncatalytic threading, it was possible to prepare polyrotaxanes in high yields with molecular weights up to 39000. These polyrotaxanes are structurally perfect in the sense that exactly two macrocycles are threaded onto each structural repeat unit. Investigations into the polymerization mechanism have demonstrated that the catalyst cucurbit[6]uril is highly sensitive toward the structure of the monomers employed and a poorly designed monomer may result in complete inactivity. Features of the mechanism are discussed in some detail.

A pilot-scale tubular reactor fitted with in-line static mixers is experimentally and theoretically evaluated for the polymerisation of methyl methacrylate (MMA). A non-isothermal and non-adiabatic axially dispersed plug-flow model is used to describe the flow characteristics of the reactor. The model is applied to the polymerisation of a concentrated MMA solution (up to 72% (v/v)). Key model parameters were attained through independent bench and pilot-scale experiments. Measured monomer conversions and polymer molecular weight were accurately predicted by model simulation. The presence of static mixers is shown to give near-ideal plug-flow operation for the experimental conditions of this study. Furthermore, an approximately four-fold increase in overall heat transfer coefficient is indicated due to the radial mixing incited by the mixers. Studies also demonstrated the importance of inhibitor kinetics on the dynamic and steady-state performance of the reactor.

Here we demonstrate the optimization of gravure printed metal ink, dielectric, and semiconductor formulations. We present a technique for nondestructively imaging printed films using a commercially available flatbed scanner, combined with image analysis to quantify print behavior. Print speed, cliche screen density, nip pressure, the orientation of print structures, and doctor blade extension were found to have a significant impact on the quality of printed films, as characterized by the spreading of printed structures and variation in print homogeneity. Organic semiconductor prints were observed to exhibit multiple periodic modulations, which are correlated to the underlying cell structure.

Quantitative microbeam Rutherford backscattering (RBS) analysis with a 1.5 MeV 4 He+ beam has determined limits on the purity of copper deposited on glass with a novel inkjet process. A tetravinyl silane tetrakisCu(I) 1,1,1,5,5,5-hexafluoroacetylacetonate (TVST[Cu]hfac) complex was heated to 70 °C and jetted onto the glass substrate through a piezoelectric ceramic print head in droplets about 0.5 mm diameter. The substrate temperature was 150 °C. Solid well-formed deposits resulted which have a copper content greater than about 90% by weight. The RBS spectra were analysed objectively using the DataFurnace code, with the assumption that the deposit was CuOx, and the validity of different assumed values of x being tested. The assumptions and the errors of the analysis are critically evaluated.

A series of elastomers were investigated, by measuring their toluene permeability and acid resistance, for their potential for use in the extraction of organics from hydrochloric acid and other membrane processes utilising acidic aqueous phases. In this study, toluene was used as a solute in aqueous solution to measure permeabilities of the elastomers, and their acid resistance was assessed after immersion in 37 wt.% hydrochloric acid by tensile-strain tests. Silicone rubber has the highest permeability among the elastomers investigated in this study, but it has poor resistance to concentrated HCl. Polyoctenamer is the best membrane material in terms of permeability and acid resistance. Other olefin based materials such as poly(ethylene-co-propylene) and poly(ethylene-co-propylene-co-diene) (EPDM) are also good candidates. The permeability generally decreases with an increase in Tg for the elastomers investigated. However, for the EPDM materials with Tg values grouped around −60 °C, the relationship between Tg and permeabilities is not clear. A model derived from Flory–Huggins Theory and the Hildebrand and Scatchard equation was used to predict the partition coefficients of toluene between the elastomers and aqueous solution, and the predictive power found to depend critically on the value employed for the water solubility parameter. The diffusion coefficients of toluene in the elastomers can be explained by considering the polymer structure.

This paper addresses the challenge of producing multifunctional composites that can simultaneously carry mechanical loads whilst storing (and delivering) electrical energy. The embodiment is a structural supercapacitor built around laminated structural carbon fibre (CF) fabrics. Each cell consists of two modified structural CF fabric electrodes, separated by a structural glass fibre fabric or polymer membrane, infused with a multifunctional polymeric electrolyte. Rather than using conventional activated carbon fibres, structural carbon fibres were treated to produce a mechanically robust, high surface area material, using a variety of methods, including direct etching, carbon nanotube sizing, and carbon nanotubein situgrowth. One of the most promising approaches is to integrate a porous bicontinuous monolithic carbon aerogel (CAG) throughout the matrix. This nanostructured matrix both provides a dramatic increase in active surface area of the electrodes, and has the potential to address mechanical issues associated with matrix-dominated failures. The effect of the initial reaction mixture composition is assessed for both the CAG modified carbon fibre electrodes and resulting devices. A low temperature CAG modification of carbon fibres was evaluated using poly(3,4-ethylenedioxythiophene) (PEDOT) to enhance the electrochemical performance. For the multifunctional structural electrolyte, simple crosslinked gels have been replaced with bicontinuous structural epoxy–ionic liquid hybrids that offer a much better balance between the conflicting demands of rigidity and molecular motion. The formation of both aerogel precursors and the multifunctional electrolyte are described, including the influence of key components, and the defining characteristics of the products. Working structural supercapacitor composite prototypes have been produced and characterised electrochemically. The effect of introducing the necessary multifunctional resin on the mechanical properties has also been assessed. Larger scale demonstrators have been produced including a full size car boot/trunk lid.

The piezoelectric ink jet (IJ) printing of an organic semiconducting ink, as applied to the fabrication of a thin film diode, has been demonstrated. IJ printed regioregular poly (3-hexylthiophene-2,5-diyl) [ rr -P3HT] semiconducting films were directly patterned on to gold thin film contact surfaces. The resulting metal–semiconductor–metal diode exhibited low leakage current and a good forward–reverse current ratio. IJ printing of the P3HT as directly patterned thin films represents a significant step toward the realisation of cheap, large area, organic microelectronic devices and transistor active matrix backplanes.

Reactions between tetraalkene silanes SiR4 (R = vinyl and allyl), copper(I) oxide, and 1,1,1,5,5,5-hexafluoroacetylacetonate (hfac) gave novel multicoordinated β-diketonate copper(I) Lewis base ligand complexes. The synthesis and spectroscopic data of tetravinylsilane biscopper(I)hfac complex (TVSB[Cu]hfac) (1), tetravinylsilane tetrakiscopper(I)hfac (TVST[Cu]hfac) (2), and tetrallylsilane triscopper(I)hfac complex (TASTri[Cu]hfac) (3) are presented, and the structural characterization of tetravinylsilane tetrakiscopper(I)hfac (TVST[Cu]hfac) (2) is reported.

Benzonorbornadiene substituted porphyrazines are homo- and copolymerised (ROMP) with norbornene using Cl 2 (Cy 3 P) 2 RuCHPh to provide dark-green and blue polymers. These novel materials have been characterised using GPC, UV-vis and EPR spectroscopy.

The self-association constant of 2-acrylamido pyridine (AAPY) and its temperature-dependence was determined by 2D-NOE-NMR spectroscopy. AAPY was shown to be a versatile polymerisable receptor for a variety of carboxylic acid derivatives. Preliminary results suggest that polymers of AAPY can be rendered main-chain chiral being potential candidates for novel sorbents.

The verification of a three-dimensional nodal transient neutronics routine in the TRAC-PF1/MOD3 Version 1.0 thermal-hydraulic system analysis computer code is discussed. This neutronics algorithm i...

Background 3′-Deoxy-3′-[18F]-fluorothymidine ([18F]FLT) is being investigated as a Positron Emission Tomography (PET) proliferation biomarker. The mechanism of cellular [18F]FLT retention has been assigned primarily to alteration of the strict transcriptionally regulated S-phase expression of thymidine kinase 1 (TK1). This, however, does not explain how anticancer agents acting primarily through G2/M arrest affect [18F]FLT uptake. We investigated alternative mechanisms of [18F]FLT cellular retention involving post-translational modification of TK1 during mitosis. Methods [18F]FLT cellular retention was assessed in cell lines having different TK1 expression. Drug-induced phosphorylation of TK1 protein was evaluated by MnCl2-phos-tag gel electrophoresis and correlated with [18F]FLT cellular retention. We further elaborated the amino acid residues involved in TK1 phosphorylation by transient transfection of FLAG-pCMV2 plasmids encoding wild type or mutant variants of TK1 into TK1 negative cells. Results Baseline [18F]FLT cellular retention and TK1 protein expression were associated. S-phase and G2/M phase arrest caused greater than two-fold reduction in [18F]FLT cellular retention in colon cancer HCT116 cells (p

Free-radical polymerization of trimethylolpropane trimethacrylate (TRIM) was carried out in the presence of a variety of porogens at room temperature, yielding transparent (macro)porous polymer monoliths. N2 BET and surface area and Hg intrusion porosimetry data from the resulting polymers showed a variety of different pore sizes and pore size distributions. In the latter, three distinct maxima at 13, 50−60, and ∼500 nm were found for small pores ( 500 nm) did not exhibit any regularity. Variation of initiator concentration, ratio of monomer to porogen, polymerization temperature, and cross-linker had no influence in obtaining transparent monoliths. Correlation of the transparency of the monoliths with the refractive index and solubility parameter of the corresponding porogens led to threshold values for the refractive index (1.42) above which, and for the total solubility parameter (∼20 (MPa)1/2) below which, a transparent polymer monolith i...

Establishing structure–activity relationships is vital if the efficacy of non-viral vectors is to match that of their viral counter-parts. Recently, we reported on the ability of a series of small molecule, cyclic polyamine disulfides to condense and cage plasmid DNA (pDNA) by a process of thermodynamically controlled templated polymerization, leading to a series of corresponding pDNA-polyplex nanoparticles able to mediate high levels of transfection with no associated cytotoxicities. The leading cyclic polyamine disulfide was shown to be the spermine tetra-amine disulfide ( TetraN-3,4,3 ). Herein we report on the significantly more challenging syntheses of cyclic disulfides with longer polyamine motifs. Two new cyclic polyamine disulfides, based on hexa- and octa-amine inserts, were prepared and their transfection efficacies and cytotoxicities compared with our previously reported cyclic tri- and tetra-amine disulfides. The new cyclic hexa- and octa-amine disulfides prove more effective at transfection in vitro , especially of lung epithelial A549 cell line. By contrast, our original cyclic tetra-amine disulfide remains the most efficient agent for the transfection of lung epithelial cells in vivo following intra-nasal administration. Hypothetical mechanistic reasons are presented to explain this outcome. Our data in toto support the concept of shorter cyclic polyamine disulfides as preferred agents for polycation-mediated controlled condensation and functional delivery of pDNA to lung epithelial cells in vivo .

Two types of porous materials derived from emulsion templates are described as potential scaffolds for tissue engineering. Novel oil-in-water particle stabilised, Pickering High Internal Phase Emulsions (HIPE) stabilised with hydroxyapatite (HAp) nanoparticles were prepared and polymerised to form stable polyHIPEs. By adding a water soluble glycidyl methacrylate (GMA) derivatised dextran as monomer to the continuous aqueous phase of the HIPEs, these Pickering-HIPEs stabilised by nontoxic biocompatible HAp nanoparticles, can be used as templates to manufacture interconnected high porosity macroporous hydrogels. A second type of emulsion templated “poly”HIPE was prepared without the need for covalent crosslinking chemistry which was replaced by a thermally-induced non-covalent scaffold forming process (thermoHIPE). These scaffolds form close to body temperature and potentially offer a new approach to the formation of injectable scaffolds for tissue engineering.