首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 22 毫秒
1.
To enhance the mechanical strength of poly(ethylene glycol)(PEG) gels and to provide functional groups for surface modification, we prepared interpenetrating (IPN) hydrogels by incorporating poly(2‐hydroxyethyl methacrylate)(PHEMA) inside PEG hydrogels. Formation of IPN hydrogels was confirmed by measuring the weight percent gain of the hydrogels after incorporation of PHEMA, as well as by ATR/FTIR analysis. Synthesis of IPN hydrogels with a high PHEMA content resulted in optically transparent and extensively crosslinked hydrogels with a lower water content and a 6 ~ 8‐fold improvement in mechanical properties than PEG hydrogels. Incorporation of less than 90 wt % PHEMA resulted in opaque hydrogels due to phase separation between water and PHEMA. To overcome the poor cell adhesion properties of the IPN hydrogels, collagen was covalently grafted to the surface of IPN hydrogels via carbamate linkages to hydroxyl groups in PHEMA. Resultant IPN hydrogels were proven to be noncytotoxic and cell adhesion study revealed that collagen immobilization resulted in a significant improvement of cell adhesion and spreading on the IPN hydrogel surfaces. The resultant IPN hydrogels were noncytotoxic, and a cell adhesion study revealed that collagen immobilization improved cell adhesion and spreading on the IPN hydrogel surfaces significantly. These results indicate that PEG/PHEMA IPN hydrogels are highly promising biomaterials that can be used in artificial corneas and a variety of other load‐bearing tissue engineering applications. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011  相似文献   

2.
Poly(2‐hydroxyethyl methacrylate) hydrogels were prepared in the presence of 30 wt% water using two series of crosslinking agents including divinylic (ethyleneglycol dimethacrylate, 1,4‐butanediol dimethacrylate, 2,3‐dihydroxybutanediol 1,4‐dimethacrylate) and diallylic (1,5‐hexadiene‐3,4‐diol and 1,5‐hexadiene) compounds, over a concentration range between 0.1 and 5 mol%. The resulting polymers were swollen in water to yield homogeneous transparent hydrogels. These hydrogels were characterised in terms of equilibrium swelling in water, tensile properties and compression stress–strain measurements. The influences of the nature and the concentration of crosslinking agent on the swelling behaviour and the mechanical properties of these hydrogels were investigated. The crosslinking efficiency of two representative agents (ethyleneglycol dimethacrylate and 1,5‐hexadiene‐3,4‐diol) was quantified by compression experiments. A much lower crosslinking efficiency (0.013) was observed for 1,5‐hexadiene‐3,4‐diol than for ethyleneglycol dimethacrylate (0.336). It is suggested that the low crosslinking efficiency of diallylic agents is responsible for a trend in properties different from that displayed by the gels crosslinked with dimethacrylates. A comparison was made to the similar effect observed previously in heterogeneous PHEMA hydrogels. © 2001 Society of Chemical Industry  相似文献   

3.
2‐Hydroxyethyl methacrylate was copolymerized with three different comonomers, methyl methacrylate (MMA), styrene (St), and N‐vinyl‐2‐pyrrolidone (NVP), respectively, to prepare porous particles crosslinked using ethylene glycol dimethacrylate (EGDMA) in the presence of an organic solvent, 1‐octanol (porogen), by means of suspension copolymerization in an aqueous phase initiated by 2,2‐azobisisobutyronitrile. Nano‐pores were observed in the particles. The pore size and the swelling properties of these particles can be controlled by changing comonomers or adjusting the crosslinker or porogen concentration. A lower crosslinker or porogen concentration favors generating smaller pores, whereas a higher concentration of a hydrophilic comonomer, higher concentration of crosslinker, and higher porogen volume ratio promote the generation of larger pores. In addition, the effects of the porous characteristics on the swelling properties were explored. The swelling capacity of the porous particles is reduced with the increase in the crosslinker concentration; however, there is a critical porogen volume ratio, in which the maximal swelling capacity is reached. Higher porosity in the particles and higher amount of hydrophilic comonomer favor a higher swelling capacity of the particles. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007  相似文献   

4.
In this study, synthesis, characterization, partial hydrolysis, and salt formation of poly(2‐hydroxyethyl methacrylate)‐co‐poly(4‐vinyl pyridine), (poly(HEMA)‐co‐poly‐(4‐VP)) copolymers were investigated. The copolymers were synthesized by free radical polymerization using K2S2O8 as an initiator. By varying the monomer/initiator ratio, chain lengths of the copolymers were changed. The copolymers were characterized by gel permeation chromatography (GPC), viscosity measurements, 1H and 13C NMR and FTIR spectroscopies, elemental analysis, and end group analysis methods. The copolymers were partially hydrolyzed by p‐toluene sulfonic acid monohydrate (PTSA·H2O) and washed with LiOH(aq) solution to prepare electrorheological (ER) active ionomers, poly(Li‐HEMA)‐co‐poly(4‐VP). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3540–3548, 2006  相似文献   

5.
Electrorheological (ER) fluids display remarkable rheological behavior, being able to convert rapidly and repeatedly from a fluid to a solid‐like when an external electric field (E) is applied or removed. In this study, electrical and ER properties of poly(Li‐2‐hydroxyethyl methacrylate)‐co‐poly(4‐vinyl pyridine), poly(Li‐HEMA)‐co‐poly(4‐VP), copolymeric salts (ionomers) were investigated. For this purpose six ionomers were synthesized with different molar masses. They were then ground‐milled for a few hours to obtain micron size ionomers. The particle sizes of the ionomers were determined by dynamic light scattering. Suspensions of ionomers were prepared in silicone oil (SO), at a series of concentrations (c = 5–30%, m/m). The gravitational stability of suspensions against sedimentation was determined at constant temperature (T = 25°C). Flow times of the suspensions were measured under no electric field (E = 0 kV/mm), and under an external applied electric field (E ≠ 0 kV/mm) strengths and a strong ER activities were observed for all the poly(Li‐HEMA)‐co‐poly(4‐VP)/SO suspensions. Further, the effects of suspension concentration, mole ratios of poly(HEMA) and poly(4‐VP), and the overall molar mass of the copolymers, shear rate, electric field strength, frequency, promoter, and temperature onto ER activities of ionomer suspensions were investigated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1065–1074, 2006  相似文献   

6.
Poly(N‐isopropylacrylamide‐co‐hydroxyethyl methacrylate) [P(NIPAM‐co‐HEMA)] copolymer was synthesized by controlled radical polymerization from respective N‐isopropylacrylamide (NIPAM) and hydroxyethyl methacrylate (HEMA) monomers with a predetermined ratio. To prepare the thermosensitive and biodegradable nanoparticles, new thermosensitive graft copolymer, poly(L ‐lactide)‐graft‐poly(N‐isoporylacrylamide‐co‐hydroxyethyl methacrylate) [PLLA‐g‐P(NIPAM‐co‐HEMA)], with the lower critical solution temperature (LCST) near the normal body temperature, was synthesized by ring opening polymerization of L ‐lactide in the presence of P(NIPAM‐co‐HEMA). The amphiphilic property of the graft copolymers was formed by the grafting of the PLLA hydrophobic chains onto the PNIPAM based hydrophilic backbone. Therefore, the graft copolymers can self‐assemble into uniformly spherical micelles ò about 150–240 nm in diameter as observed by the field emission scanning electron microscope and dynamic light scattering. Dexamethasone can be loaded into these nanostructures during dialysis with a relative high loading capacity and its in vitro release depends on temperature. Above the LCST, most of the drugs were released from the drug‐loaded micelles, whereas a large amount of drugs still remains in the micelles after 48 h below the LCST. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012  相似文献   

7.
A series of 2‐hydroxyethyl methacrylate/1‐vinyl‐3‐(3‐sulfopropyl)imidazolium betaine (HEMA/VSIB) copolymeric gels were prepared from various molar ratios of HEMA and the zwitterionic monomer VSIB. The influence of the amount of VSIB in copolymeric gels on their swelling behavior in water and various saline solutions at different temperatures and the drug‐release behavior, compression strength, and crosslinking density were investigated. Experimental results indicated that the PHEMA hydrogel and the lower VSIB content (3%) in the HEMA/VSIB gel exhibited an overshooting phenomenon in their dynamic swelling behavior, and the overshooting ratio decreased with increase of the temperature. In the equilibrium water content, the value increased with increase of the VSIB content in HEMA/VSIB hydrogels. In the saline solution, the water content for these gels was not affected by the ion concentration when the salt concentration was lower than the minimum salt concentration (MSC) of poly(VSIB). When the salt concentration was higher than the MSC of poly(VSIB), the deswelling behavior of the copolymeric gel was more effectively suppressed as more VSIB was added to the copolymeric gels. However, the swelling behavior of gels in KI, KBr, NaClO4, and NaNO3 solutions at a higher concentration would cause an antipolyelectrolyte phenomenon. Besides, the anion effects were larger than were the cation effects in the presence of a common anion (Cl?) with different cations and a common cation (K+) with different anions for the hydrogel. In drug‐release behavior, the addition of VSIB increased the drug‐release ratio and the release rate. Finally, the addition of VSIB in the hydrogel improved the gel strength and crosslinking density of the gel. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2888–2900, 2001  相似文献   

8.
Poly(2‐hydroxyethyl methacrylate)‐co‐polylactide (PHEMA‐co‐PLA) and its corresponding cyhalothrin‐loaded ultrafine particles were successfully synthesized and prepared, respectively. The chemical structures of the copolymers have been confirmed by Fourier transform infrared spectroscopy (FTIR), 1H‐nuclear magnetic resonance (1H‐NMR), 13C‐nuclear magnetic resonance (13C‐NMR), and thermogravimetric analysis (TGA). Furthermore, the particle size, the cyhalothrin loading content (LC), and the cyhalothrin release behavior were investigated. PHEMA‐co‐PLA proved to be a good material for the preparation of ultrafine particles for lipophilic pesticide delivery. The developed cyhalothrin‐loaded PHEMA‐co‐PLA ultrafine particles showed good dispersity in water and sustained release behavior. In addition, it is easy to be prepared by both nanoprecipitation method and emulsion/solvent evaporation method. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013  相似文献   

9.
Narrow‐dispersion or monodisperse with stable and smooth surface polymer microspheres were prepared without a significant coagulum by precipitation polymerization in the absence of any stabilizer. The monomer glycidyl metharylate (GMA) was copolymerized with ethyleneglycol dimethacrylate (EGDMA) as crosslinker by precipitation polymerization technique with 2,2′‐azobisisobutyronitrile as initiator in neat acetonitrile. The effects of the content of EGDMA on the polymerization characteristics and size/uniformity of the microspheres were investigated. The onset of the thermal degradation temperature at higher temperature and the swelling test suggest that the prepared particles were highly crosslinked. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010  相似文献   

10.
The internal morphologies for a series of heterogeneous PHEMA and P[HEMA‐co‐MeO‐PEGMA] [PHEMA = poly(2‐hydroxyethyl methacrylate), MeO‐PEGMA = poly(ethylene glycol) methyl ether methacrylate] hydrogels were characterized by scanning electron microscopy (SEM) in conjunction with a sample drying procedure, and by laser scanning confocal microscopy (LSCM) without prior drying. Compared to SEM, LSCM was far simpler and more rapid technique for imaging hydrogels. LSCM also allowed the native hydrated morphology of the hydrogels to be characterized, whereas SEM could only characterize the morphology of samples in their dehydrated state. No dehydration method used in this study preserved the true native morphology, but plunge freezing/freeze drying was the most suitable method that best preserved the native morphology for all hydrogel compositions. Refrigerated freezing/freeze‐drying and critical point drying introduced significant morphological artifacts, the severity of the artifacts being dependant on the sample's composition and Tg. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013  相似文献   

11.
The DNA adsorption properties of poly‐L ‐lysine‐immobilized poly(2‐hydroxyethyl methacrylate) (pHEMA) membrane were investigated. The pHEMA membrane was prepared by UV‐initiated photopolymerization and activated with epichlorohydrin. Poly‐L ‐lysine was then immobilized on the activated pHEMA membrane by covalent bonding, via a direct chemical reaction between the amino group of poly‐L ‐lysine and the epoxy group of pHEMA. The poly‐L ‐lysine content of the membrane was determined as 1537 mg m?2. The poly‐L ‐lysine‐immobilized membrane was utilized as an adsorbent in DNA adsorption experiments. The maximum adsorption of DNA on the poly‐L ‐lysine‐immobilized pHEMA membrane was observed at 4 °C from phosphate‐buffered salt solution (pH 7.4, 0.1 M; NaCl 0.5 M) containing different amounts of DNA. The non‐specific adsorption of DNA on the plain pHEMA membrane was low (about 263 mg m?2). Higher DNA adsorption values (up to 5849 mg m?2) were obtained in which the poly‐L ‐lysine‐immobilized pHEMA membrane was used. Copyright © 2003 Society of Chemical Industry  相似文献   

12.
A series of 2‐hydroxyethyl methacrylate (HEMA) and sodium acrylate (SA50) copolymeric gels were prepared from HEMA and the anionic monomer SA50 with various molar ratios. The influence of SA50 on the copolymeric gels on their swelling behavior in deionized water at different temperatures and various pH buffer solutions was investigated. Results indicated that the poly(2‐hydroxyethyl methacrylate) (PHEMA) hydrogels exhibited an overshooting phenomenon in their dynamic swelling behavior. The maximum overshooting value decreased with increasing of the temperature. The same results were also found in the HEMA/SA50 copolymeric gels with a lower SA50 content. On the contrary, the overshooting phenomenon for HEMA/SA50 copolymeric gels with a higher content of SA50 was exhibited only under higher temperature (over 35°C). These copolymer gels were used to assess drug release and drug delivery in this article. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1360–1371, 2001  相似文献   

13.
Networked, crosslinked poly[(2‐hydroxyethyl methacrylate)‐co‐(ethylene glycol dimethacrylate)] (HEMA‐EGDM) was synthesized by frontal polymerization (FP) using azobisisobutyronitrile as initiator. HEMA‐EGDM copolymers of similar composition were also synthesized by suspension polymerization. The two sets of copolymers were characterized for functional groups (IR), pore volume (mercury intrusion porosimetry), surface area (nitrogen adsorption) and morphology (scanning electron microscopy). FP‐generated polymeric network structures had higher internal pore volumes and surface areas but their surface morphologies were inferior to those of copolymers synthesized by suspension polymerization. Copyright © 2004 Society of Chemical Industry  相似文献   

14.
An interpenetrating polymer network (IPN) with shape memory properties was prepared by using poly(2‐hydroxyethyl methacrylate) (PHEMA) and poly(ethylene oxide) (PEO). PHEMA acts as a fixed phase and PEO as a switching phase. The switching action of PEO is due to the reversible process of melting and crystallization. It was observed that the shape recovery of the IPN increases with increasing crosslinker concentration up to an optimum value and decreases thereafter. In addition to the shape memory property, the IPNs show a reversible change in optical properties from translucent to opaque. The change in optical properties is quite different from that observed in a semicrystalline polymer system where the transparency increases as a result of the melting of crystals. This behaviour of the IPN is explained in terms of H‐bonding of PEO with PHEMA. Fourier transform infrared spectroscopy was used to study the H‐bonding between PEO and PHEMA. © 2019 Society of Chemical Industry  相似文献   

15.
NR‐graft‐PHEMA latexes were synthesized by the use of graft emulsion polymerization. By increasing the HEMA monomer concentration, we found that the grafting percentage (GP) also increased. In addition, GP increased significantly at low initiator concentrations before it leveled off at moderate concentrations, and a slight decrease was observed at high initiator concentrations. NR‐g‐PHEMA latexes were prepared as pervaporation membranes for the separation of water–acetone mixtures. From the equilibrium swelling, the nonideal behavior of membrane swelling in water–acetone mixtures was found such that there appeared the maximum swelling degree at a certain concentration of liquid mixtures. Moreover, the water concentration at maximum swelling shifted to high water concentration with increasing amount of graft‐PHEMA. The sorption study suggested the preferential sorption of water on the membranes. Also, the sorption isotherms implied that there was a coupling between water and acetone molecules. Pervaporation separation of water–acetone mixtures was studied with NR‐g‐PHEMA membranes. As the feed water concentration increased, the partial water fluxes increased in contrast to the partial fluxes of acetone. From the permeation ratio, θw, the strong coupling of acetone on the water transport was observed, particularly for the membrane with high graft‐PHEMA under acetone‐rich conditions. As the feed temperature increased, the total permeation across the membranes was enhanced. The partial fluxes of water and acetone as a function of temperature followed the Arrhenius relationship by which the activation energies for permeation were estimated as 3.53 kJ/mol for water and 21.95 kJ/mol for acetone. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009  相似文献   

16.
A configurational biomimetic imprinting technique was used to prepare recognition sites for glucose in copolymers of 2‐hydroxyethyl methacrylate (HEMA) and methacrylic acid (MAA) prepared with crosslinking agents containing poly(ethylene glycol) (PEG). We report on the structure, diffusive, and recognition characteristics of these gels, the effect of the type and ratio of crosslinking agent, as well as the template/comonomer ratios on glucose binding ability. The highest equilibrium glucose binding was found as 2.67 mg/g dry polymer when PEG monomethacrylate (PEGMMA) was used in combination with tetra ethylene glycol dimethacrylate (TEGDMA) (50%) as a crosslinking agent. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 103: 432–441, 2007  相似文献   

17.
Amphiphilic copolymers of poly(styrene‐co‐2‐hydroxyethyl acrylate) (SHEA) and poly(styrene‐coN, N‐dimethylacrylamide) (SAD) of different compositions were prepared by free radical copolymerization and characterized by different techniques. Depending on the nature of the solvent and the densities of interacting species incorporated within the polystyrene matrices, novel materials as blends or interpolymer complexes with properties different from those of their constituents were elaborated when these copolymers are mixed together. The specific interpolymer interactions of hydrogen bonding type and the phase behavior of the elaborated materials were investigated by differential scanning calorimetry (DSC) and Fourier transform infra red spectroscopy (FTIR). The specific interactions of hydrogen bonding type that occurred within the SHEA and within their blends with the SAD were evidenced by FTIR qualitatively by the appearance of a new band at 1626 cm?1 and quantitatively using appropriate spectral curve fitting in the carbonyl and amide regions. The variation of the glass transition temperature with the blend composition behaved differently with the densities of interacting species. The thermal degradation behavior of the materials was studied by thermogravimetry. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008  相似文献   

18.
Narrow‐distribution, well‐defined comb‐like amphiphilic copolymers are reported in this work. The copolymers are composed of poly(methyl methacrylate‐co‐2‐hydroxyethyl methacrylate) (P(MMA‐co‐HEMA)) as the backbones and poly(2‐(dimethylamino)ethyl methacrylate) (PDMAEMA) as the grafted chains, with the copolymer backbones being synthesized via atom‐transfer radical polymerization (ATRP) and the grafted chains by oxyanionic polymerization. The copolymers were characterized by gel permeation chromatography (GPC), Fourier‐transform infrared (FT‐IR) spectroscopy and 1H NMR spectroscopy. The aggregation behavior in aqueous solutions of the comb‐like amphiphilic copolymers was also investigated. 1H NMR spectroscopic and surface tension measurements all indicated that the copolymers could form micelles in aqueous solutions and they possessed high surface activity. The results of dynamic light scattering (DLS) and scanning electron microscopy (SEM) investigations showed that the hydrodynamic diameters of the comb‐like amphiphilic copolymer aggregates increased with dilution. Because of the protonizable properties of the graft chains, the surface activity properties and micellar state can be easily modulated by variations in pH. Copyright © 2004 Society of Chemical Industry  相似文献   

19.
2‐Hydroxyethyl methacrylate (HEMA) solution (1–10 wt %) was prepared in methanol and phosphate glass fibers were immersed in that solution for 5 min before being cured (irradiation time: 30 min) under UV radiation. Maximum polymer loading (HEMA content) was found for the 5 wt % HEMA solution. Degradation tests of the fibers in aqueous medium at 37°C suggested that the degradation of the HEMA‐treated fibers was lower than that of the untreated fibers. X‐ray photoelectron spectroscopy revealed that HEMA was present on the surface of the fibers. Using 5 wt % HEMA‐treated fibers, poly(caprolactone) matrix unidirectional composites were fabricated by in situ polymerization and compression molding. For in situ polymerization, it was found that 5 wt % HEMA‐treated fiber‐based composites had higher bending strength (13.8% greater) and modulus (14.0% greater) than those of the control composites. For compression molded composites, the bending strength and modulus values for the HEMA‐treated samples were found to be 27.0 and 31.5% higher, respectively, than the control samples. The tensile strength, tensile modulus, and impact strength of the HEMA composites found significant improvement than that of the untreated composites. The composites were investigated by scanning electron microscopy after 6 weeks of degradation in water at 37°C. It was found that HEMA‐treated fibers inside the composite retained much of their original integrity while the control samples degraded significantly. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009  相似文献   

20.
Interpenetrating polymer networks (IPNs) of polydimethylsiloxane (PDMS) and poly(2‐hydroxyethyl methacrylate) (PHEMA) were prepared by sequential method. The dynamic mechanical parameters of obtained IPNs and their variations with the structural composition were evaluated. The results for the IPNs were compared with corresponding physically blended systems. The tensile properties and damping factor (tan δ) were assessed by stress–strain measurement and dynamic mechanical thermal analysis (DMTA), respectively. The glass–rubber transition temperature (Tg) was assessed by DMTA and differential scanning calorimetry (DSC). The results showed higher tensile strength and elongation at break for IPNs than those for physical blends. The shifts of Tg for that two components that make up the IPNs were greater than those for corresponding blends. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3480–3485, 2002  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号