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Hydrogel of poly(N-n-propylacrylamide) was prepared and its swelling dependence on temperature and pressure was investigated. Dramatic volume change of the gel with pressure and temperature was observed.
A range of hydrogel copolymer membranes of poly(2-hydroxyethyl methacrylate) with 4-vinylpyridine or 4-vinyl-4 -methyl-2,2 -bipyridine have been made and their permeabilities to a series of transition metal salts determined. Ion transport is characterized by an initial induction period prior to the onset of steady-state permeation. This period varies depending on the ion under study and can be...
Samples of poly(N-vinyl-2-pyrrolidone (VP)-co-methyl methacrylate (MMA)), containing 41-76.5 wt% MMA, have been prepared by a controlled, semicontinuous copolymerization procedure and swollen to equilibrium in water at various temperatures T (283-343 K) to yield hydrogels in which the network structure is maintained by physical crosslinking involving sequences of MMA units. The effective crosslinking...
New anionic polyelectrolyte gels were prepared by the chemical crosslinking reaction of highly phosphorylated poly(vinyl alcohol)(P-PVA) with glutaraldehyde. The structures of the gels were determined by both i.r. and solid-state 13 C n.m.r. spectroscopy. The various types of polyanionic gels having high- or low-swelling characteristics and different degrees of hardness could be prepared...
Semi-interpenetrating polymer network (semi-IPN) hydrogel membranes composed of β-chitin and poly(ethylene glycol) (PEG) diacrylate macromer were synthesized and characterized for future biomedical application. PEG macromer/β-chitin dissolved in formic acid was cast to prepare films, followed by subsequent crosslinking with 2,2-dimethoxy-2-phenylacetophenone by u.v. irradiation. Photocrosslinked...
Poly(β-acryloxypropionic acid) (PAOPA) hydrogels crosslinked by ethylene glycol dimethacrylate (EDMA) have been prepared by using both a chemical initiator and by γ-irradiation. Polymerizations were conducted in bulk and also in the presence of water. Characterizations were made by swelling, compression-strain measurements and differential scanning calorimetry (d.s.c.). The findings show the following:...
Ozone-induced graft polymerization of hydrogel forming polymers on to polypropylene (PP) membranes and fibres was studied. A higher rate of water absorption and higher water content at equilibrium were found when diethylene glycol methacrylate (DEGMA) rather than 2-hydroxyethyl methacrylate (HEMA) was grafted on to microporous substrates. Ozone-induced grafting of HEMA and DEGMA on to polypropylene...
The free radical copolymerizations of dimethylacrylamide (DMA) with ethylene dimethacrylate (EDMA) and of DMA with methyl methacrylate (MMA) have been conducted over a wide range of conversion. Compositions of resultant crosslinked poly(DMA-co-EDMA) and of linear poly(DMA-co-MMA) were determined by nitrogen analysis and FTi.r., respectively. Appropriate modern procedures applied to the data yielded...
Poly(ester-ether-ester) triblock copolymers composed of poly(ethylene glycol) (PEG) and lactones, d,l-lactide or ε-caprolactone, were crosslinked with β-chitin to prepare semi-interprenetrating polymer network (IPN) hydrogels by the u.v. irradiation method. Triblock copolymers were synthesized by bulk polymerization using low toxic stannous octoate as catalyst, or without catalyst. Photocrosslinked...
In this paper a synthetic procedure is described towards a new class of methacrylated dextrans which are sensitive to hydrolysis. These methacrylated dextrans, which can be used for the development of biodegradable hydrogels, were obtained by grafting L-lactide onto 2-hydroxyethyl methacrylate (HEMA), followed by activation of the terminal hydroxyl group with N,N -carbonyldiimidazole (CDI), yielding...
The swelling and porosity change of the pentaerythritol triacrylate (PENTA) homopolymer and PENTA-butyl acrylate (BA) copolymers were investigated as a function of PENTA content (80, 60, 40 and 20 wt%). Polymers were synthesized by the suspension polymerization method using cyclohexanol and 2-ethylhexanol as inert diluents. The solubility parameter of poly(PENTA) (18.2 MPa 12 ) was...
Thermoreversible copolymer hydrogel based on poly(ethylene oxide) and poly(N-isopropyl acrylamide) has been prepared by γ-radiation technique. The utility of 13 C n.m.r. spectroscopy in elucidating the structure and copolymer composition has been demonstrated. The volume transition as a function of temperature in these copolymers has been studied by swelling ratio measurements. Unlike...
The synthesis of a new cross-linked structure, with sucrose and diepoxide monomers, possessing the properties of a highly swellable hydrogel polymer is reported. Characterization studies of its structure and water effects were carried out in dried and hydrated samples by CP-MAS 13 C n.m.r., by wide-band 1 H and 2 H n.m.r. and by differential thermal analysis. The results...
Hydrogels with varying crosslink densities and ionic moieties were prepared from the ternary systems N-vinyl 2-pyrrolidone/itaconic acid/water by irradiation with γ rays at ambient temperature. The influence of external stimuli such as pH, temperature and ionic strength of the swelling media and the type of buffer on the equilibrium swelling properties were investigated. Hydrogels showed typical pH...
Determination of average molecular weight between cross-links (M c ) of itaconic acid-containing poly(vinyl pyrrolidone) and maleic acid-containing poly(acrylamide) hydrogels sensitive to pH changes of the swelling medium was investigated. Poly-electrolyte hydrogels with varying compositions were prepared in the form of rods from ternary mixtures of N-vinyl 2-pyrrolidone/itaconic acid/water...
Water and solute or drug transport in crosslinked polymeric materials was investigated to determine the effects of polymer morphology, composition and solute properties on transport behavior. Two crosslinked polymer systems, poly(2-hydroxyethyl methacrylate-co-methyl methacrylate) (P(HEMA-co-MMA)) and poly(vinyl alcohol) (PVA), were used in water transport and solute release experiments. Structural...
Recently we reported on chitosan hydrogel systems having excellent laser damage resistance. The measured laser damage threshold (LDT) was better than BK7 glass and quartz, commonly used inorganic optical materials, and 20 to 35 times higher than commercial PMMA, a popular polymer optical material. In this study, we continue our investigation of the phase transition behavior of water within the hydrogels...
This paper describes the synthesis and characterization of 2-(methacryloyloxy) ethyl-l-lactate and 2-(methacryloyloxy)ethyl-di-l-lactate. These compounds were obtained by reaction of l-lactide and 2-hydroxyethyl methacrylate (HEMA) at a molar ratio of 1:2 using stannous octoate as catalyst. After a purification step using preparative HPLC, the obtained products were characterized by 1 H-NMR,...
The physical immobilisation of a range of crown ethers within hydrogel membranes of a range of water contents has been examined. The efficiency of the immobilisation process increases with increasing size of the crown and decreasing water content (and thus mean pore radius) of the hydrogels. Successful occlusion was achieved with dicyclohexano-18-crown-6 in a poly(2-hydroxyethyl methacrylate) membrane...
The degradation behavior of highly swollen, chemically cross-linked hydrogels was characterized by monitoring changes in their mass loss, degree of swelling and compressive modulus. The hydrogels were used as model systems to investigate the hydrolytic degradation process in cross-linked networks. The trends of the three measured properties differ substantially from those seen for linear degradable...
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