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Over the years, studies showed that hydrogels can be produced through synthetic route to overcome the limitations in obtaining natural-based hydrogels. Biomass resources offer potential alternatives as renewable feedstocks due to their outstanding biodegradability and biocompatibility. Oil palm mesocarp fiber (MF) is the biomass residue obtained after the pressing of palm fruits during palm oil extraction. There is approximately 11 % MF generated from palm fruits after oil extraction. However, the applications of MF are limited. This study aimed to investigate the development of hydrogels from holocellulose MF instead of commonly used cellulose which involving several pretreatment steps, through acid cross-linkers. Holocellulose MF was selected as polymer for chemical cross-linking with two inexpensive and nontoxic hydrophilic organic acids, citric acid and acetic acid for hydrogel production. Comparison study was carried out to evaluate the physicochemical properties, and degree of swelling, as well as gel content in different media for both acids in the production of hydrogel from holocellulose MF. Results indicated that the optimum concentrations of citric acid and acetic acid for gel content and degree of swelling were 5 M and 2 M, respectively. Both optimized hydrogels exhibited comparable profiles in terms of morphology, thermal stability and functional groups, in addition to showing similar degree of swelling profile in different media, i.e., salt solution, acidic, neutral to alkaline, implying their distinctive characteristics. In summary, holocellulose MF is suitable for the production of hydrogel with citric acid and acetic acid as crosslinkers for different desired applications. [ABSTRACT FROM AUTHOR]

Nonsolvent induced phase separation (NIPS) method using NMP/water system was adopted to prepare PVA/PVC thin films and were characterized by FTIR & FE-SEM analysis. Mechanical strength measurements indicated that an optimum composition of PVA/PVC has maximum tensile strength and might be due to the intercalation of viscous PVA into the stiff PVC matrix. Degree of swelling (DS) and water contact angle (WCA) measurements showed greater wettability of the films with increasing PVA content as is revealed from the higher film porosity and diminished contact angle. Pure water flux (PWF) and mean pore size were studied to determine the water permeation capacity of the film. Vapour permeability of various films was evaluated by using three different aliphatic alcohols viz. Methanol, ethanol and propanol. Barrier property and selectivity in permeation were studied for a particular PVA/PVC composition with moderate number and size of the pores which exhibited minimum permeation capacity. [ABSTRACT FROM AUTHOR]

The application of protein-based drugs in oral delivery system is limited due to the harsh environment of the gastrointestinal (GI) tract. Herein, a pH-responsive nano-sized complex with chitosan (CH) and alginate (AL) was fabricated without cross-linker as an oral vehicle for bursting release of protein at the target location to enhance the efficacy. Using bovine serum albumin (BSA) as a model cargo protein, four optimized complexation processes (LG1, LG2, LG3, and LG4) were selected by changes of variables (total concentration (TC), the ratio of CH to AL (CH/AL, w/w), and mixing time (MT)) and further modifications using encapsulation efficiency and complex size. Size, ζ-potential, morphology, BSA release, and swelling degrees of the complexes were evaluated under simulated gastrointestinal conditions (pH 2.0 and 7.4). LG1 and LG4 completely retained BSA in complexes at pH 2.0 after 2 h (BSA release percentage is 0%) and exhibited bursting release at pH 7.4 after 1 h (84.03 and 67.59%, respectively). Low absolute ζ-potential value (about 10 mV), large size (over 10000 nm) and polymer morphology demonstrated that the pH-responsive complexes inhibited protein release at pH 2.0 through the molecule-molecule aggregation. Relatively high absolute ζ-potential value (about 45 mV), ideal swelling ability (around 2), and polymer morphology revealed that the complex promoted the release at 7.4 through both micro- and macroscale swelling. Results demonstrate that the CH-BSA-AL complex through LG4 has a potential for administering proteinbased drugs or vaccines orally due to its highest effective dose (78.78 μg/mL). [ABSTRACT FROM AUTHOR]

Cassava stems contain up to 40% starch (by dry mass) and are currently discarded as agricultural waste. The current study aims to understand the physicochemical traits of cassava stem and root starches for investigating trends in industrial cassava applications. In total, 11 traits of both cassava stem and root starches of 15 genotypes are investigated. All the examined traits of cassava root and stem starches vary by genotype. The amylose contents of root and stem starches are in the range of 19.0–33.0% and 18.44–34.51%, respectively. The resistant starch of root and stem starches are in the range of 1.72–17.72% and 4.42–13.37%, respectively. Only the starch content, solubility, and swelling power of root starches are significantly higher than those of stem starches. The root starch gel is more stable than the stem starch gel after the fourth and fifth freeze‐thaw cycles. Furthermore, principal component analysis calculated based on starch and amylose contents, degree of swelling, digestibility, and freeze‐thaw stability demonstrates that genotypes GW46, GW88, S1, E26, and GC49 gain higher scores than control varieties South China 12 and South China 205, which are the most favorable ones by farmers in China because of good root yields. [ABSTRACT FROM AUTHOR]

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Pyrolysis gasoline (Py gas) is used as an octane enhancer of gasoline as it is rich in aromatics. However, removal of carcinogenic benzene from Py gas before blending with gasoline is important to meet the fuel specifications. The main focus of this present study is to determine the sorption kinetics and sorption isotherm of a fabricated insitu nano silver/polyvinyl alcohol (insitu nano Ag/PVA) membrane for pervaporative separation of benzene from model Py gas [mixture of benzene (aromatic) and 1-octene (aliphatic)]. The thickness, surface morphological structure (Atomic Force Microscopy) and degree of swelling of the fabricated membrane were determined. The highest pervaporation separation index achieved for the selected system was 14.259 kg/m2/h at 303 K, with 30 volume% benzene in model Py gas using a downstream pressure of 1 mm of Hg. The sorption kinetics of benzene in insitu nano Ag/PVA membrane obeyed the Elovich model while the Temkin isotherm model fitted the experimental data of the chosen system most accurately. [ABSTRACT FROM AUTHOR]

A method for producing metamaterial cross-linked polyvinyl alcohol–magnetite nanoparticles based on the chemical deposition of Fe3O4 ions with NH3 solution into the volume of polymer granules is considered. The granules of the metamaterial are used as a sensor element for determining the composition of solutions by optical micrometry: the kinetic dependences of the swelling of the granules in solutions of aliphatic acids and their sodium salts and sugars are studied. The doping of the polymer with Fe3O4 particles increases the measurement accuracy at the initial part of the kinetic curve. [ABSTRACT FROM AUTHOR]

In this study, polysulfone (PSf) nanocomposite membranes (NCM) have been fabricated by reinforcement with silica-modified zeolite (SiO2-MZ) and polyimide (PI)-SiO2-MZ as inorganic nanocomposite (NC) fillers. To evaluate the improvement in structural, mechanical, and thermal properties of PSf matrix, these nanofillers were incorporated systematically from 1 wt% to 10 wt%. Morphological analysis using transmission electron microscopy and scanning electron microscopy shows better compatibility between PI-SiO2-MZ as the inorganic nanofiller and polymer matrix as compared to SiO2-MZ filler. Physical characteristics of NCMs were studied by Fourier transform infrared spectroscopy and X-ray diffraction analysis. The appropriate ratio of PI-SiO2-MZ as nanofiller in PSf matrix was found through structural analysis. Thermal analysis using differential scanning calorimetry revealed an increase in glass transition temperature (T g) with increasing filler concentration. Young's modulus of PSf/SiO2-MZ NCM (10 wt%) was found to be 1109 MPa, which was improved to 1438 MPa for PSf/PI-SiO2-MZ (10 wt%) NCM. Membrane properties like swelling degree and porosity were also calculated. The degree of swelling of NCMs decreases with decrease in the hydrophilicity of the solvent. Antibacterial properties of NCMs were explored against four bacterial strains namely Klebsella pneumonia, Salmonella typhi, Bacillus subtilis, and Staphylococcus aureus. Good antibacterial activities were obtained for PSf membranes reinforced with PSf/PI-SiO2-MZ NC filler. [ABSTRACT FROM AUTHOR]

Ion-exchange membranes (IEMs) are a core component that greatly affects the performance of electrochemical energy conversion processes such as reverse electrodialysis (RED) and all-vanadium redox flow battery (VRFB). The IEMs used in electrochemical energy conversion processes require low mass transfer resistance, high permselectivity, excellent durability, and also need to be inexpensive to manufacture. Therefore, in this study, thin-reinforced anion-exchange membranes with excellent physical and chemical stabilities were developed by filling a polyethylene porous substrate with functional monomers, and through in situ polymerization and post-treatments. In particular, the thin-reinforced membranes were made to have a high ion-exchange capacity and a limited degree of swelling at the same time through a double cross-linking reaction. The prepared membranes were shown to possess both strong tensile strength (>120 MPa) and low electrical resistance (2). As a result of applying them to RED and VRFB, the performances were shown to be superior to those of the commercial membrane (AMX, Astom Corp., Japan) in the optimal composition. In addition, the prepared membranes were found to have high oxidation stability, enough for practical applications.

Cationization of wood and cotton celluloses using 3-chloro-2-hydroxypropyltrimethylammonium chloride in aqueous suspensions in the presence of various amounts of NaOH followed by cross-linking with epichlorohydrin was studied in detail. The compositions of the cationic cellulose ethers and the reaction efficiency depended strongly on the ratio of the alkylating mixture components. The physicochemical properties of the synthesized samples were studied using chemical analysis, IR spectroscopy, X-ray structure analysis, and centrifugation to determine water absorption. The content of cationic groups and concentration of cationic cellulose in the epichlorohydrin cross-linking stage had decisive effects on the degree of swelling in water and aqueous NaCl solution of the cross-linked cationic cotton and wood celluloses. [ABSTRACT FROM AUTHOR]

The interaction of dissolved substances with polar groups of a hydrophilic polymer is analyzed. The effect of the size and hydration energy of cations of the elements of the first and second groups of the Periodic Table, as well as halide anions on the structure of the polymer matrix and the composition of the polymer gel was studied. Quantitative estimates of the effects of the concentration of the external solution on volume and composition of polyvinyl alcohol gels were carried out. [ABSTRACT FROM AUTHOR]

The influence of the concentration of an external solution, the nature of the polar groups, and the amount of cross-linking in the resins on the degree of swelling of the ionites synthesized based on the polystyrene cross-linked by divinylbenzene is investigated. It is shown that the share of the volume of the external solution in an ionite depends only on the amount of cross-linking and is independent of the nature of the polar groups and the composition of the external solution. The dependence of the share of the volume occupied by the external solution in the swollen ionite on the percentage of divinylbenzene is determined. The model of the polymer matrix in which the concentration of the external solution affects the degree of polymer swelling but does not affect the volume of the external solution in the granule is proposed. It is shown that the "sandwich" model of the polymer matrix is most convenient for describing the properties of polymer gels in which the concentration of the external solution affects the degree of swelling of the polymer but does not affect the volume of the phase of the external solution in the granule. [ABSTRACT FROM AUTHOR]

Dissolved oil palm empty fruit bunch (EFB) cellulose in NaOH/urea solvent was mixed with sodium carboxymethylcellulose (NaCMC) to form a green regenerated superabsorbent hydrogel. The effect of concentration of epichlorohydrin (ECH) as the crosslinker on the formation, physical, and chemical properties of hydrogel was studied. Rapid formation and higher gel content of hydrogel were observed at 10% concentration of ECH. The superabsorbent hydrogel was successfully fabricated in this study with the swelling ability >100,000%. Hydrogel with higher concentration of ECH showed opposite trend by having higher superabsorbent property than that of lower concentration. The covalent bond of C O C was observed with Attenuated total reflectance fourier transform infrared (ATR-FT-IR) spectroscopy to confirm the occurrence of crosslinking. The physical and chemical properties of hydrogel were affected by swelling phenomenon. Hydrogel with higher degree of swelling exhibited lower moisture retention and higher transparency. Moreover, the weight of the superabsorbent hydrogel increased with the decrement of pH value of external media (distilled water). This study provided substantial information on the effect of different percentage of ECH as crosslinker on hydrogel basic properties. Furthermore, this study affords correlation of many essential driving forces that affected hydrogel superabsorbent property. [ABSTRACT FROM AUTHOR]

Herein we report on the preparation and structural characterization of six amphiphilic polymer conetworks (APCN) based on end-linked amphiphilic 'core-first' star block copolymers, comprising methyl methacrylate and 2-(dimethylamino)ethyl methacrylate as the monomer repeating units in the hydrophobic and hydrophilic blocks, respectively. The various APCNs differed either in the arm composition or in the arm molecular weight. APCN synthesis was accomplished via the one-pot, sequential group transfer polymerization (GTP) of cross-linker, hydrophobic monomer, hydrophilic monomer, and cross-linker again. The soluble precursors to the APCNs, i.e., the star homopolymers, the star block copolymers and the initial cross-linker cores, were characterized in terms of their composition, size and size dispersity. The degrees of swelling in tetrahydrofuran were found to increase with the molecular weight of the arms of the stars of the APCNs, whereas the degrees of swelling in water increased with the content in hydrophilic units in the arms of the constituting stars. Small-angle neutron scattering (SANS) indicated that most APCNs nanophase separated in D2O. The structure and size of the hydrophobic domains determined by fitting the SANS data to an appropriate model could be correlated with the molecular architecture of the APCNs. Finally, polarized light microscopy showed that all APCNs were birefringent both in water and in the dried state. [ABSTRACT FROM AUTHOR]

Environmentally-friendly packaging based on whey protein offers the potential to replace petroleum-based oxygen barrier materials. Effective crosslinking of the whey protein is a prerequisite for this application. To quantify the effect of storage time on the post-crosslinking of whey protein isolate based films, swelling tests were conducted in order to determine the degree of swelling (DoS). In addition, the degree of crosslinking (DoC) and the crosslinking density (CLD) were calculated using existing models with new data from water vapour sorption isotherm measurements. The results showed that increasing storage time led to decreased swelling of whey protein isolate based films (p < .05) and increased DoC and CLD (p < .05). Comparison of the films on day 1 and day 21 showed that the crosslinking increased by a factor of 3 while the DoS reduced by almost half. The results of this study demonstrate that the storage time of whey protein isolated based films is a crucial factor for crosslinking. [ABSTRACT FROM AUTHOR]

The aim of this paper was to investigate the effect of a silicalite type zeolite on PDMS-zeolite composites. The obtained results show that the introduction of a silicalite type zeolite into polysiloxane matrices results in a change of the equilibrium degree of swelling of the composites in toluene, their hardness and their thermal stability. With increasing amount of zeolite, the time required to achieve the equilibrium degree of swelling (DSe) is reduced, the DSe decreases and the hardness increases. Two ranges of the effect of the zeolite concentration on the composite characteristics were noted. At zeolite concentrations up to about 12 % there are significant changes of the DSe and the hardness with zeolite concentration, while these effects are considerably less pronounced at higher concentrations. The results obtained show that the silicalite type zeolite acts as a reinforcing filler. We believe that with increasing zeolite concentration in the composite the total number of established polymer-zeolite interactions increases, as does the spatial irregularity of the polymer network, but that the density of the interactions decreases. This could be the most probably explanation for the changes in the characteristics of the composite with changing zeolite concentration.

The aim of this paper was to investigate the effect of a silicalite type zeolite on PDMS-zeolite composites. The obtained results show that the introduction of a silicalite type zeolite into polysiloxane matrices results in a change of the equilibrium degree of swelling of the composites in toluene, their hardness and their thermal stability. With increasing amount of zeolite, the time required to achieve the equilibrium degree of swelling (DSe) is reduced, the DSe decreases and the hardness increases. Two ranges of the effect of the zeolite concentration on the composite characteristics were noted. At zeolite concentrations up to about 12% there are significant changes of the DSe and the hardness with zeolite concentration, while these effects are considerably less pronounced at higher concentrations. The results obtained show that the silicalite type zeolite acts as a reinforcing filler. We believe that with increasing zeolite concentration in the composite the total number of established polymer-zeolite interactions increases, as does the spatial irregularity of the polymer network, but that the density of the interactions decreases. This could be the most probably explanation for the changes in the characteristics of the composite with changing zeolite concentration.

In the past several decades, hydrogels have been extensively studied for use in various biomedical and industrial applications. Successful use of hydrogels in these applications greatly relies on the ability to control mechanical and transport properties in a refined manner; however, current hydrogel design often encounters an undesirable inverse dependency between the degree of swelling and elastic modulus. To resolve this challenge, we hypothesized that an interpenetrating network (IPN) gel in which collagen fibers are chemically linked to a polymeric gel would allow us to control the elastic modulus over a broad range while reducing the change in the degree of swelling. We examined this hypothesis by preparing a collagen–polyacrylamide IPN gel via in situ assembly, so that two disparate networks are chemically linked via Michael reaction between collagen and polyacrylamide. The resulting IPN gel successfully demonstrated the independency between the degree of swelling and the elastic modulus. We suggest that the results of this study will be broadly useful in controlling hydrogel properties in an elaborate manner, in turn advancing various molecular and cell therapies. [ABSTRACT FROM AUTHOR]

The aim of the present study is to design a mucoadhesive nano-carrier system which retains at the site of application and maximizes the therapeutic potential of anticancer drug as well as reduces their systemic side effects. In the present study PVA nanofibers of Docetaxel were prepared using electrospinning machine. The resulting nanofibers were characterized through various parameters such as surface morphology, drug loading,in-vitrodrug release, tensile strength, mucoadhesiveness, drug permeability, degree of swelling and anticancer activities against selective cell lines to establish their therapeutics potential. On the basis of various evaluation results, we may conclude that the current approach comprising polymeric nanofibers can be successfully used for local delivery of anticancer drug. [ABSTRACT FROM PUBLISHER]

The effects of long-term storage and retrogradation on the stability of the gel properties of radiation-synthesized super water absorbents (SWA) made from cassava starch and acrylic acid were explored in this study. Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and transmission electron microscopy (TEM) analyses were used to explore the retrogradation phenomenon. TEM and scanning area electron diffraction (SAED) images revealed the presence of starch nanocrystallites and increase of crystalline state in SWA matrix after 24 months storage. FT-IR peak ratios and enthalpy changes in DSC analysis also confirmed retrogradation of aged SWA samples. However, no sharp peak was observed in XRD diffractograms which is mainly due to the nanostarches present in the SWA. The most critical property affected by starch retrogradation in SWA is the degree of swelling. The degree of swelling of SWA was greatly reduced from 148 to 30 g/g while the gel fraction remained stable after 24 mos. The aged SWA samples with low degree of swelling due to retrogradation returned to their high and stable soil water content after 15 d in unsterile pure garden soil. Despite being exposed to high energy gamma radiation of starch with acrylic acid to form SWA, wherein possible oxidation and chemical modification of starch may take place, retrogradation can still occur. Lowering the storage temperature evidently suppressed the effect of starch retrogradation in SWA. Suppression of starch retrogradation in the optimized SWA is crucial to prolong its marketable life. • Radiation-processed starch/acrylic acid SWA decreases swelling property over time. • Gel fraction of SWA remains stable upon storage. • Starch recrystallization in SWA was confirmed by FT-IR, DSC, and TEM analysis. • TEM and SAED images revealed nanocrystallites formation in aged SWA. • High soil water retention of retrograded SWA restored after being rehydrated. [ABSTRACT FROM AUTHOR]

Various nanocomposite gels were prepared using cellulose nanowhiskers (CNWs) or chitin nanowhiskers (ChNWs) as reinforcing fillers and hydroxypropyl cellulose (HPC), carboxymethyl cellulose (CMC), or chitosan as network polymers. The use of CNWs with low surface charge induced significant CNWs aggregations, which were well explained by depletion effect. Young's modulus E and swelling ratio Q of CNWs/HPC · CMC gels were highest at zero electrolyte concentration and decreased above 0.01 M electrolyte, whereas stress at break σ of the gels showed its minimum at zero electrolytes and increased with an addition of electrolytes. In the case of ChNWs/chitosan gels, maximum of E and Q was located at 0.01 M electrolyte concentration, and σ did not indicate clear tendency with electrolyte concentration. Although all gels indicated an increase in E and a decrease in Q with an increase in whisker content, the most remarkable changes were observed under an absence of electrolytes, whereas the changes under the presence of electrolytes were somewhat negligible. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Highlights: [•] Starch/PVA blend films were prepared using citric acid (CA) and glutaraldehyde (GLU) as plasticizer and crosslinker, respectively. [•] Blend film shows increased tensile strength and degree of swelling. [•] The mechanical properties of Grewia optiva fibre reinforced composite blend films have been found to be higher than those of the starch/PVA cross-linked blend films. [•] TGA showed the good thermal properties of blend films. [ABSTRACT FROM AUTHOR]

Amlodipine besylate microspheres for intranasal administration were prepared with an aim to avoid first-pass metabolism, to achieve controlled blood level profiles and to improve therapeutic efficacy. Hydroxypropyl Guar, a biodegradable polymer, was used in the preparation of microspheres by employing water in oil emulsification solvent evaporation technique. The formulation variables were drug concentration, emulsifier concentration, temperature, agitation speed and polymer concentration. All the formulations were evaluated for particle size, particle shape and surface morphology by scanning electron microscopy, percentage yield, drug entrapment efficiency, in vitro mucoadhesion test, degree of swelling and in vitro drug diffusion through sheep nasal mucosa. The microspheres obtained were free lowing, spherical and the particles ranged in size from 13.4±2.38 µm to 43.4±1.92 µm very much suitable for nasal delivery. Increasing polymer concentration resulted in increased drug entrapment efficiency and increased particle size. Amlodipine besylate was entrapped into the microspheres with an efficiency of 67.2±1.18 % to 81.8±0.64 %. The prepared microspheres showed good mucoadhesion properties, swellability and sustained the release of the drug over a period of 8 h. The data obtained were analysed by fitment into various kinetic models; it was observed that the drug release was matrix diffusion controlled and the release mechanism was found to be non- Fickian. Stability studies were carried out on selected formulations at 5±3°, 25±2°/60±5% RH and 40±2°/75±5% RH for 90 days. The drug content was observed to be within permissible limits and there were no significant deviations in the in vitro mucoadhesion and in vitro drug diffusion characteristics. [ABSTRACT FROM AUTHOR]

The study evaluated the compatibility of chloroform, ether, and xylene with poly(dimethyl siloxane) (PDMS) based sealer. Freshly mixed sealer was placed in 90 glass molds with 5 mm diameter and 2 mm thickness. All samples were stored in 75% relative humidity at 37°C for 2 weeks. All the samples were divided into three groups: group A – chloroform; group B – ether, and group C – xylene and immersed in fresh solvent at room temperature. The specimens were weighed before and after immersion for each group at the end of 2, 5, and 10 min. The swelling ratio was calculated for all the groups. Intergroup comparison revealed no difference in the mean swelling ratio for 2, 5, and 10 min (P > 0.001; Tukey HSD Post Hoc). Intragroup comparison revealed significant difference in swelling ratio between 2 and 5 min for group B and group C (P < 0.001; Paired t test). Ether has the highest compatibility with PDMS-based sealer after 2 min followed by xylene after 5 min. [ABSTRACT FROM AUTHOR]

physical model of the cytoskeleton based on synthetic polyelectrolyte hydrogel of polymethacrylic acid has been proposed. From the physicochemical point of view, the structures of polyelectrolyte gel and the cytoskeleton show a high degree of similarity. It has been shown that polyelectrolyte gel can shorten and produce mechanical stress in response to changes in the composition of the surrounding solution. The mechanical properties of the model gel have been evaluated: Young modulus (2-6 kPa), stress relaxation time (0.1-1 s), and apparent viscosity (0.3-3 kPa s). The viscoelastic properties of the gel depend on the degree of its swelling. It has been demonstrated that the mechanical properties of gels of polymethacrylic acid are close to those of biological objects. [ABSTRACT FROM AUTHOR]

Abstract: Group transfer polymerization and sequential addition of monomer and cross-linker were employed for the preparation of two new polymer structures, one of a polymer network and the other of a star polymer. The synthesis was completed in two steps, involving the synthesis of linear methyl methacrylate (MMA) arms of degree of polymerization of 20, followed by their cross-linking using a mixture of MMA monomer and ethylene glycol dimethacrylate (EGDMA) cross-linker. In this study, the volume of the cross-linking mixture was varied systematically. Furthermore, two mixture compositions were employed, involving MMA:EGDMA molar ratios of 1:1 and 3:1, leading to two series of polymeric materials. It was found that at a given cross-linking mixture composition, a larger volume of the cross-linking mixture favored the formation of polymer networks, whereas a smaller volume favored the formation of star polymers. The linear precursors, the star polymers and the extractables from the polymer networks were characterized by gel permeation chromatography in tetrahydrofuran (THF). The absolute weight-average molecular weight, the number of arms and the hydrodynamic radii of the star polymers, as determined using static and dynamic light scattering in THF, respectively, and their average radii as determined by atomic force microscopy, increased as the volume of the cross-linking mixture increased. The gravimetrically measured degrees of swelling in THF, the network sol fraction and the percentage of branched polymer in the sol fraction decreased as the volume of the cross-linking mixture increased. [Copyright &y& Elsevier]

Abstract: Blends of Eudragit®E (EE) and polymeric excipients using thermal analysis and FTIR spectroscopy were examined. The interactions amongst the blend components were quantified in terms of parameters K 1 and K 2 in Schneider equation and were explained on the basis of interactions between the functional groups of the blend constituents investigated by FTIR spectroscopy. EE formed miscible blends with EC and polyelectrolyte complexes increasing in strength in the order: ES

Abstract: Samples of poly[1-(3-sulfopropyl)-2-vinyl-pyridinium-betaine] (PSPV) have been synthesized to high conversion by free radical polymerization in aqueous solution of the zwitterionic monomer SPV with several concentrations of the crosslinker N,N′-methylene-bis-acrylamide (MBA). The densities of the resultant xerogels increased regularly with the content of MBA. Hydrogels obtained by swelling them in water and aqueous KSCN solution were examined by gravimetric and dimensional analysis. The water contents increased with decreasing content of MBA, the value of 92.7wt% at the lowest MBA content being higher than that for other zwitterionic hydrogels. Enhanced swelling occurred in 1M aq. KSCN at each MBA content, the total swelling being 98.1wt% at the lowest crosslinker content. Swelling increased with increasing temperature. An approximate procedure to formulating swelling equilibrium in term of the volume fraction of water in hydrogel, in conjunction with the van’t Hoff equation, yields a small positive value for the enthalpy of swelling. This is compared with values derived similarly for other hydrogels. [Copyright &y& Elsevier]

This paper deals with the mechanical properties and degree of swelling (DS) of starch/PVA blend film with the functional groups i.e., hydroxyl and carboxyl group, of additives. Starch/PVA blend films were prepared by using the mixing process. Glycerol (GL) with 3 hydroxyl group, sorbitol (SO) with 6 hydroxyl group, succinic acid (SA) with 2 carboxyl group, malic acid (MA) with 1 hydroxyl and 2 carboxyl group, tartaric acid (TA) with 2 hydroxyl and 2 carboxyl group and citric acid (CA) with 1 hydroxyl and 3 carboxyl group were used as additives. The results of measured tensile strength (TS) and elongation (%E) verified that both hydroxyl and carboxyl group as a functional groups increased the flexibility and strength of the film. Values of DS for GL-added and SA-added films were low. However, DS values of the films added MA, TA or CA with both hydroxyl and carboxyl group were comparatively high. When the film was dried at low temperature, the properties of the films were evidently improved. The reason is probably because the hydrogen bonding was activated at low temperature. [ABSTRACT FROM AUTHOR]

Starch/polyvinyl alcohol (PVA) blend films were prepared successfully by using starch, polyvinyl alcohol (PVA), glycerol (GL) sorbitol (SO) and citric acid (CA) for the mixing process. The influence of mixing time, additional materials and drying temperature of films on the properties of the films was investigated. With increase in mixing time, the tensile strength (TS), elongation (%E), degree of swelling (DS) and solubility (S) of the film were equilibrated. The equilibrium for TS, %E, DS and S value was 20.12 MPa, 36.98%, 2.4 and 0.19, respectively. The mixing time of equilibrium was 50 min. TS, %E, DS and S of starch/PVA blend film were examined adding glycerol (GL), sorbitol (SO) and citric acid (CA) as additives. At all measurement results, except for DS, the film adding CA was better than GL or SO because hydrogen bonding at the presence of CA with hydroxyl group and carboxyl group increased the inter/intramolecular interaction between starch, PVA and additives. Citric acid improves the properties of starch/PVA blend film compared to glycerol and sobitol. When the film was dried at low temperature, the properties of the films were clearly improved because the hydrogen bonding was activated at low temperature. [ABSTRACT FROM AUTHOR]

Linear homopolymers and randomly cross-linked homopolymer networks of 2-(dimethylamino)ethyl methacrylate of various molecular weights (MWs) were synthesized by group transfer polymerization in the bulk. 1-methoxy-1-(trimethylsiloxy)-2-methyl propene was used as the initiator, while tetrabutylammonium bibenzoate served as the catalyst. Ethylene glycol dimethacrylate was the cross-linker used for the network synthesis at an 8-fold molar excess with respect to the initiator. Gel permeation chromatography in tetrahydrofuran was used to characterize the linear homopolymers in terms of their MW and molecular weight distribution (MWD). Although the experimental MWs did not match the theoretical MWs, they were reasonably close to them. The MWDs were rather broad with polydispersity indices ranging between 1.5 and 1.9. The monomer conversion was relatively high, ranging from 97% to 74% for theoretical degrees of polymerization (DPs) from 5 to 500. No polymerization was observed for an attempted DP of 1000. Networks with molar ratios of monomer to initiator (nominal DPs) from 5 to 200 were prepared, while an attempted synthesis with a nominal DP of 500 did not yield a network. The networks were characterized in terms of their degree of swelling in water and the effects of DP, pH, salt concentration and temperature were investigated. [Copyright &y& Elsevier]

The recent literature on chemically cross-linked amphiphilic polymer networks is reviewed. The main subjects covered are network synthesis, characterization, modeling and applications. Special mention is made to more modern methods for amphiphilic network synthesis and in particular to those involving controlled polymerization techniques. A key question regarding synthesis is which method gives the most perfect networks. On the characterization side is the issue of microphase separation of amphiphilic networks in water and the morphologies obtained in these systems, in comparison with the morphologies of amphiphilic linear block copolymers in water. Major recent advances: The most important developments of the past year in the field of amphiphilic polymer networks involved mainly new syntheses: cross-linked stars of various star architectures, cross-linked linear chains of various architectures and compositions, poly(tetrahydrofuran)- and poly(propylene fumarate)-based networks, tricomponent networks containing silicon, and cross-linked poly(acrylic acid)-grafted Pluronics. A first crude model was also developed which shows that amphiphilic networks prefer to be mostly in the microphase separated state. Extensive and systematic experimental studies on network microphase separation are yet to be performed. [Copyright &y& Elsevier]

Ion-exchange membranes (IEMs) are a core component that greatly affects the performance of electrochemical energy conversion processes such as reverse electrodialysis (RED) and all-vanadium redox flow battery (VRFB). The IEMs used in electrochemical energy conversion processes require low mass transfer resistance, high permselectivity, excellent durability, and also need to be inexpensive to manufacture. Therefore, in this study, thin-reinforced anion-exchange membranes with excellent physical and chemical stabilities were developed by filling a polyethylene porous substrate with functional monomers, and through in situ polymerization and post-treatments. In particular, the thin-reinforced membranes were made to have a high ion-exchange capacity and a limited degree of swelling at the same time through a double cross-linking reaction. The prepared membranes were shown to possess both strong tensile strength (>120 MPa) and low electrical resistance (<1 Ohm cm 2 ). As a result of applying them to RED and VRFB, the performances were shown to be superior to those of the commercial membrane (AMX, Astom Corp., Japan) in the optimal composition. In addition, the prepared membranes were found to have high oxidation stability, enough for practical applications.

The diffusion of six azo and five anthraquinone derivatives through nylon 6, poly(ethylene terephthalate) and secondary cellulose acetate films were studied under high hydrostatic pressures of up to 3000 bar and at temperatures 80-130 °C, by analyzing the diffusion profiles yielded in a stacked multiple film, placed in the solution of the diffusant. It was found that the diffusion coefficient, D, of the diffusant decreased with increasing pressure, giving a linear relationship between In D and the pressure, the slope of which gave the activation volume for the diffusion, ΔV. It was revealed ΔV increased linearly with increasing intrinsic molecular volume of the diffusant, V, the slopes being different between the azo and the anthraquinone derivatives. The ratio of ΔV to V ( ΔV/ V) ranged from 0.13 to 0.93, depending in a sensitive manner on the degree of swelling of the polymer matrix which in turn was varied by the solvent. The overall results could be explained in accordance with the formulation, V + ΔV= V, where V represents the free volume contribution. It was proposed that V is increased by solvation when the solvent is good for the diffusant. [ABSTRACT FROM AUTHOR]

• Disc-shaped implants were formed from cross-linked δ-valerolactone-based copolymers. • Incorporation of a PEGylated cross linkable δ-valerolactone copolymer alters the physico-chemical properties of the discs. • The discs caused no adverse effects following 1 month implantation in vivo. • Facile post-loading resulted in high drug loading and sustained release in vitro. • The discs tailorable drug loading and in vitro release increases their functionality. Implantable drug delivery systems, formed from degradable and non-degradable polymers, can offer several advantages over traditional dosage forms for sustained drug delivery. The majority of degradable implant systems developed to date are composed of poly(lactide-co-glycolide) (PLGA). However, PLGA-based systems are not suitable for the delivery of all drugs. Each drug is unique in terms of physico-chemical properties, and polymer-drug compatibility plays a significant role in determining a drug formulation's performance. In this study, two novel cross-linkable δ-valerolactone-based copolymers were synthesized and used to prepare cross-linked disc-shaped implants. The manipulation of the composition of the discs and conditions used during drug loading were found to influence various aspects of the delivery system performance including the degree of swelling, degradation, drug-loading and in vitro release. The polymeric discs resulted in no adverse effects following subcutaneous implantation in naïve rats. These studies support further development of cross-linkable valerolactone matrices as implantable formulations for sustained drug delivery. [Display omitted] [ABSTRACT FROM AUTHOR]

Superabsorbent polymers (SAP) are of major interest as materials to control the cement hydration process. The swelling behavior of the SAPs significantly influences the performance of the resulting concrete by slowly releasing polymer-bound water in order to maintain a consistent w / c value. A round-robin test conducted by the RILEM Technical Committee 260-RSC showed that the same batch of polymer can lead to large deviations in concrete performance and this was assumed to originate in different storage conditions of the SAP. In this contribution the change in the performance of two SAPs, a crosslinked poly(acrylate) and a crosslinked poly(acrylate- co -acrylamide), was assessed after ageing in standard climate, at 50 °C, and under UV irradiation. During storage in standard climate or 50 °C, ageing led to dehydration of the SAP, and this subsequently led to a higher water uptake during swelling. By contrast, UV irradiation reduced the water uptake, most likely as a result of photo-crosslinking. Dynamic water vapor sorption experiments indicated a strong dependence of the water uptake on both the ambient humidity and the temperature. As a result, cement mixtures containing SAP must be calculated on the dry mass of the SAP rather than the actual weight on site. A standard procedure of how to pack and handle SAP to be used in concrete is also provided.

Hydrogels incorporated with hydrophobic motifs have received considerable attention to recapitulate the cellular microenvironments, specifically for the bio-mineralization of a 3D matrix. Introduction of hydrophobic molecules into a hydrogel often results in irregular arrangement of the motifs, and further phase separation of hydrophobic domains, but limited efforts have been made to resolve this challenge in developing the hydrophobically-modified hydrogel. Therefore, this study presents an advanced integrative strategy to incorporate hydrophobic domains regularly in a hydrogel using self-assembled domains formed with polymer cross-linkers, building blocks of a hydrogel. Self-assemblies formed by polymer cross-linkers were examined as micro-domains to incorporate hydrophobic motifs in a hydrogel. The self-assembled structures in a pre-gelled solution were confirmed with the fluorescence analysis and the hydrophobicity of a hydrogel could be tuned by incorporating the hydrophobic chains in a controlled manner. Overall, the results of this study would greatly serve to tuning performance of a wide array of hydrophobically-modified hydrogels in drug delivery, cell therapies and tissue engineering. [ABSTRACT FROM AUTHOR]

Physically crosslinked sacran gels were prepared, and the degree of swelling in pure water and in 0.9 wt% NaCl solution was measured. The sacran gel showed anomalous swelling with a degree of swelling of 6100 in pure water and 530 in the saline solution. The degree of swelling varied remarkably by the pH of the pre-gel solution. This high swelling ratio might originate from the large mesh consisting of extremely long chains of sacran. [ABSTRACT FROM AUTHOR]