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1.
Poly(diglycidyl maleate‐co‐stearyl methacrylate) (P(DGMA‐co‐SMA)) with reactive epoxy groups was synthesized by reaction of poly(maleic anhydride‐co‐stearyl methacrylate) (P(MA‐co‐SMA)) and epichlorohydrin. The effect of precipitant on self‐assembly behaviors of the resultant copolymer was investigated. It was found that vesicles and nanotubule liked aggregates can be obtained through self‐assembly of P(DGMA‐co‐SMA) in THF solution using CH3CH2OH (EtOH) as precipitant while spheral aggregates can be obtained using H2O as precipitant. The mechanism of the self‐assembly behavior was discussed. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007  相似文献   

2.
pH and thermo‐responsive graft copolymers are reported where thermo‐responsive poly(N‐isopropylacrylamide) [poly(NIPAAm), poly A ], poly(N‐isopropylacrylamide‐co‐2‐(diethylamino) ethyl methacrylate) [poly(NIPAAm‐co‐DEA), poly B ], and poly(N‐isopropylacrylamide‐co‐methacrylic acid) [poly(NIPAAm‐co‐MAA), poly C ] have been installed to benzaldehyde grafted polyethylene glycol (PEG) back bone following introducing a pH responsive benzoic‐imine bond. All the prepared graft copolymers for PEG‐g‐poly(NIPAAm) [ P‐N1 ], PEG‐g‐poly(NIPAAm‐co‐DEA) [ P‐N2 ], and PEG‐g‐poly(NIPAAm‐co‐MAA) [ P‐N3 ] were characterized by 1H‐NMR to assure the successful synthesis of the expected polymers. Molecular weight of all synthesized polymers was evaluated following gel permeation chromatography. The lower critical solution temperature of graft copolymers varied significantly when grafted to benzaldehyde containing PEG and after further functionalization of copolymer based poly(NIPAAm). The contact angle experiment showed the changes in hydrophilic/hydrophobic behavior when the polymers were exposed to different pH and temperature. Particle size measurement investigation by dynamic light scattering was performed to rectify thermo and pH responsiveness of all prepared polymers. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013  相似文献   

3.
A novel temperature responsive copolymer, poly[2‐(2‐methoxyethoxy)ethyl methacrylate‐co‐oligo(ethylene glycol)methacrylate‐co‐N‐hydroxymethyl acrylamide] [P(MEO2MA‐co‐OEGMA‐co‐HMAM)], was synthesized by atom transfer radical polymerization. pH responsive poly(methacrylic acid) (PMAA) was synthesized by reversible addition‐fragmentation chain transfer polymerization. After the hydroxyl groups on P(MEO2MA‐co‐OEGMA‐co‐HMAM) were transformed into azide groups and the carboxyl groups on PMAA were transformed into alkyne groups respectively, a novel temperature and pH responsive hydrogel was fabricated by click chemistry between the azide‐P(MEO2MA‐co‐OEGMA‐co‐HMAM) and alkyne‐PMAA in the presence of CuSO4 and sodium ascorbate in aqueous solution. The rheological kinetics of gel formation demonstrated that gelation had commenced within 5 min at 25 °C, since then the storage modulus (G′) was higher than the loss modulus (G″). SEM images of hydrogel morphology and the swelling ratios of hydrogel at different temperatures and pH proved that the formed hydrogel had temperature and pH sensitivities. Bovine serum albumin was used as a model to evaluate the sustained release of the hydrogel; the results indicated that the hydrogel was a promising candidate for controlling protein drug delivery. © 2015 Society of Chemical Industry  相似文献   

4.
In this work, biocompatible hydrogel matrices for wound‐dressing materials and controlled drug‐release systems were prepared from poly[hydroxyethyl methacrylate‐co‐poly(ethylene glycol)–methacrylate] [p(HEMA‐co‐PEG–MA] films via UV‐initiated photopolymerization. The characterization of the hydrogels was conducted with swelling experiments, Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis (differential scanning calorimetry), and contact‐angle studies. The water absorbency of the hydrogel films significantly changed with the change of the medium pH from 4.0 to 7.4. The thermal stability of the copolymer was lowered by an increase in the ratio of poly(ethylene glycol) (PEG) to methacrylate (MA) in the film structure. Contact‐angle measurements on the surface of the p(HEMA‐co‐PEG–MA) films demonstrated that the copolymer gave rise to a significant hydrophilic surface in comparison with the homopolymer of 2‐hydroxyethyl methacrylate (HEMA). The blood protein adsorption was significantly reduced on the surface of the copolymer hydrogels in comparison with the control homopolymer of HEMA. Model antibiotic (i.e., minocycline) release experiments were performed in physiological buffer saline solutions with a continuous flow release system. The amount of minocycline release was shown to be dependent on the HEMA/PEG–MA ratio. The hydrogels have good antifouling properties and therefore are suitable candidates for wound dressing and other tissue engineering applications. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009  相似文献   

5.
A well‐defined graft copolymer, polystyrene‐graft‐poly(methyl methacrylate), was synthesized in two steps. In the first step, styrene and p‐vinyl benzene sulfonyl chloride were copolymerized via reversible addition–fragmentation chain transfer polymerization (RAFT) in benzene at 60 °C with 2‐(ethoxycarbonyl)prop‐2‐yl dithiobenzoate as a chain transfer agent and 2,2′‐azobis(isobutyronitrile) as an initiator. In the second step, poly[styrene‐cop‐(vinyl benzene sulfonyl chloride)] was used as a macroinitiator for the atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) in toluene at 80 °C with CuCl as a catalyst and 2,2′‐bipyridine as a ligand. With sulfonyl chloride groups as the initiating sites for the ATRP of MMA, high initiation efficiencies were obtained. Copyright © 2006 Society of Chemical Industry  相似文献   

6.
The glass transition temperature of a series of samples of the poly[(methyl methacrylate)‐co‐(ethyl acrylate)] copolymer, synthesized at low conversion, were calculated theoretically using the equations of Barton and Johnston. The values obtained are more precise when the probabilities of the compositional diads are derived from the 13C NMR data instead of the classical method utilizing reactivity ratios. This can be observed more clearly when the copolymer samples are synthesized at high conversion. Introduction of configuration (tacticity) at the diad level confirms the above observations and slightly improves the calculated values of Tg compared to the initial formulae which were only taking into account the compositional sequences of the copolymer. © 2001 Society of Chemical Industry  相似文献   

7.
pH‐Responsive amphiphilic branched copolymers were prepared from poly(ethylene glycol) methyl ether methacrylate (PEGMA), 2‐(diethylamino)ethyl methacrylate (DEAEMA), 2‐(tert‐butylamino)ethyl methacrylate (tBAEMA), and ethylene glycol dimethacrylate (EGDMA) utilizing a thiol‐modified free radical polymerization. The molecular structures of copolymers were confirmed by proton nuclear magnetic resonance spectroscopy (1H NMR) and triple‐detection gel permeation chromatography (tri‐GPC). The aqueous solution behaviors of the obtained copolymers were investigated by dynamic light scattering (DLS). The DLS data showed that about 16 nm polymer particles comprising of hydrophobic poly(tert‐butylamino)ethyl methacrylate (PtBAEMA) and poly(diethylaminoethyl methacrylate (PDEAEMA) core, hydrophilic PEGMA corona were formed above pH 8. With the decrease of pH from 8 to 6, a dramatic increase in the hydrodynamic radius of polymer particles from 16 nm to 130 nm was observed resulting from the protonation of the PDEAEMA segment. Moreover, in vitro drug release behaviors of the resulting polymer assemblies at different pH values were also investigated to evaluate their potential as sustained release drug carriers. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42183.  相似文献   

8.
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   

9.
Hydrogels based on commercially available 2‐(2‐methoxyethoxy)ethyl methacrylate (MEO2MA), with methacrylic acid (MAA) as comonomer, are studied. The incorporation of an ionizable monomer, such as MAA, in a thermosensitive system leads to the formation of hydrogels able to respond to pH and temperature according to their monomeric composition. Thus, at low pH, the acid groups of MAA are protonated, and they do not contribute to increase the hydrophilic balance, and collapse of the hydrogels occurs around room temperature. For temperatures below that of collapse, the degree of swelling increases with increasing MEO2MA content. In contrast, at neutral or basic pH, the ionization of the acid groups contributes to increase the hydrophilicity and the osmotic pressure, leading to polyelectrolyte behaviour. In this regime, the swelling capacity increases and the thermosensitivity decreases with increasing MAA content in the hydrogels. These properties make poly(MEO2MA‐co‐MAA) hydrogels suitable candidates for use in oral controlled delivery of hydrophobic drugs. This possibility is explored using ibuprofen as a model drug, after a complete study of the swelling kinetics. Copyright © 2010 Society of Chemical Industry  相似文献   

10.
A copolymer of chloroprene (CP) and isobutyl methacrylate (iBMA) [poly(CP-co-iBMA)] was prepared in benzene by radical copolymerization. For comparison, the graft copolymer of iBMA onto polychloroprene (CR) [poly(CR-g-iBMA)] was also prepared. The glass transition temperature of the poly(CP-co-iBMA) was about ?32.4°C. The monomer reactivity ratios determined by the Finneman-Ross method were given as r1 (CP) = 1.80 and r2 (iBMA) = 0.74 in the copolymerization of CP and iBMA, respectively. Miscibility of blends of CR and poly(isobutyl methacrylate) (PiBMA), prepared by casting from tetrahydrofuran (THF) solution, was investigated by their glass transition temperature behaviors and morphologies. Although the blends of CR and PiBMA were incompatible, the addition of poly(CP-co-iBMA) or poly(CR-g-iBMA) enhanced miscibility between the two base polymers. It was found that the extent of partial miscibility becomes larger when adding poly(CP-co-iBMA) than poly(CR-g-iBMA) as a third component to the CR/PiBMA blend of 50/50 wt % composition. © 1993 John Wiley & Sons, Inc.  相似文献   

11.
Cellulase was immobilized directly on methyl methacrylate‐glycidyl methacrylate copolymer (MMA‐co‐GMA) and methyl methacrylate‐2‐hydroxy ethyl methacrylate copolymer (MMA‐co‐HEMA) by covalent attachment and crosslinking methods. The properties of the immobilized cellulase were investigated and compared with those of the free one. For the assays carried out through crosslinking method at 25°C and pH 7, the retained activities were found to be 91.92% and 74.63%, respectively, for MMA‐co‐GMA and MMA‐co‐HEMA crosslinked with 0.1% of 1‐cyclohexyl‐3‐(2‐morpholino‐ethyl) carbodiimide metho‐p‐toluenesulfonate (CMCT), respectively. The immobilized cellulase had better stability and higher retained activities with respect to pH, temperature, and storage stability than the free one. In the repeated use experiments, the immobilized cellulase using (MMA‐co‐GMA)‐CMCT (0.1%) and (MMA‐co‐HEMA)‐CMCT (0.1%) did not change after 10 and eight times of repeated use and maintained 67% and 62% from their original activities after 25 times, respectively. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010  相似文献   

12.
An investigation of the behavior of poly(methyl methacrylate co ethyl acrylate) with a commercially available filament-type pyrolysis unit and gas chromatogaph was conducted. It has been hypothesized that the quantity of ethyl acrylate monomer produced under the conditions of the experiment is dependent upon the number of ethyl acrylate–methyl methacrylate bonds contained in the copolymer. These observations were made possible by a standardized samples-handling technique in which a uniformsize disk was pyrolyzed at a maximum pyrolysis temperature of 600°C. This enabled reproducible pyrolysis gas chromatograms to be obtained and permitted pyrolysis products of copolymers containing different ratios of ethyl acrylate and methyl methacrylate to be compared. An examination of sequence distribution data, obtained with the aid of a sequence distribution program for copolymers, showed sufficient agreement with the pyrolysis data to support the hypothesis. It has been demonstrated that pyrolysis gas chromatography may be applied to experimentally determine the sequence distribution of copolymers.  相似文献   

13.
Bio‐based amphiphilic triblock copolymers with 100% renewably sourced poly(trimethylene ether) glycol (PO3G) as the hydrophobic blocks and statistical copolymer of 2‐(2‐methoxyethoxy)ethyl methacrylate (MEO2MA) and oligo(ethylene glycol)methacrylate (OEGMA) [P(MEO2MA‐stat‐OEGMA)] as the hydrophilic blocks are synthesized and characterized. It is found that the molar ratio of MEO2MA/OEGMA among the resulting copolymers is approximately 70/30. The degree of polymerization (DP) of P(MEO2MA‐stat‐OEGMA) block ranges from 16 to 90, and the DP of PO3G block is fixed at 35. The amphiphilic copolymers could form core‐shell micelles self‐assembly in aqueous solution at low concentrations, and the micelles are in spherical shape with sizes varying from 121 to 188 nm. With the increasing length of hydrophilic blocks, the critical micelle concentration increases from 2.15 to 13.8 mg L?1, and the lower critical solution temperature improves from 32.5 to 38.4 °C. The in vitro doxorubicin (DOX) release study shows that all DOX‐loaded micelles have a higher release rate at 37 °C than that at 25 °C. Cytotoxicity test reveals that the blank micelles are nearly nontoxic. These results indicate that the block copolymer micelles containing 100% renewably sourced PO3G can serve as a potential drug delivery carrier. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46112.  相似文献   

14.
The miscibility and crystallization kinetics of the blends of random poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) [P(HB‐co‐HV)] copolymer and poly(methyl methacrylate) (PMMA) were investigated by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). It was found that P(HB‐co‐HV)/PMMA blends were miscible in the melt. Thus the single glass‐transition temperature (Tg) of the blends within the whole composition range suggests that P(HB‐co‐HV) and PMMA were totally miscible for the miscible blends. The equilibrium melting point (T°m) of P(HB‐co‐HV) in the P(HB‐co‐HV)/PMMA blends decreased with increasing PMMA. The T°m depression supports the miscibility of the blends. With respect to the results of crystallization kinetics, it was found that both the spherulitic growth rate and the overall crystallization rate decreased with the addition of PMMA. The kinetics retardation was attributed to the decrease in P(HB‐co‐HV) molecular mobility and dilution of P(HB‐co‐HV) concentration resulting from the addition of PMMA, which has a higher Tg. According to secondary nucleation theory, the kinetics of spherulitic crystallization of P(HB‐co‐HV) in the blends was analyzed in the studied temperature range. The crystallizations of P(HB‐co‐HV) in P(HB‐co‐HV)/PMMA blends were assigned to n = 4, regime III growth process. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3595–3603, 2004  相似文献   

15.
A polydimethylsiloxane (PDMS) macroazoinitiator was synthesized from bis(hydroxyalkyl)‐terminated PDMS and 4,4′‐azobis‐4‐cyanopentanoic acid by a condensation reaction. The bifunctional macroinitiator was used for the block copolymerization of ethyl methacrylate (EMA) and 2‐(trimethylsilyloxy)ethyl methacrylate (TMSHEMA) monomers. The poly(DMS‐block‐EMA) and poly(DMS‐block‐TMSHEMA) copolymers thus obtained were characterized using Fourier transform infrared and 1H NMR spectroscopy and differential scanning calorimetry. After the deprotection of trimethylsilyl groups, poly(DMS‐block‐HEMA) and poly(DMS‐block‐EMA) copolymer film surfaces were analysed using scanning electron microscopy and X‐ray photoelectron spectroscopy. The effects of the PDMS concentration in the copolymers on both air and glass sides of films were examined. The PDMS segments oriented and moved to the glass side in poly(DMS‐block‐EMA) copolymer film while orientation to the air side became evident with increasing DMS content in poly(DMS‐block‐HEMA) copolymer film. The block copolymerization technique described here is a versatile and economic method and is also applicable to a wide range of monomers. The copolymers obtained have phase‐separated morphologies and the effects of DMS segments on copolymer film surfaces are different at the glass and air sides. Copyright © 2010 Society of Chemical Industry  相似文献   

16.
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   

17.
A novel series of temperature‐sensitive poly[(N‐isopropylacrylamide)‐co‐(ethyl methacrylate)] (p(NIPAM‐co‐EMA)) microgels was prepared by the surfactant‐free radical polymerization of N‐isopropylacrylamide (NIPAM) with ethyl methacrylate (EMA). The shape, size dispersity and volume‐phase transition behavior of the microgels were investigated by transmission electron microscopy (TEM), ultraviolet–visible (UV–Vis) spectroscopy, dynamic light scattering (DLS) and differential scanning calorimetry (DSC). The transmission electron micrographs and DLS results showed that microgels with narrow distributions were prepared. It was shown from UV–Vis, DLS and DSC measurements that the volume‐phase transition temperature (VPTT) of the p(NIPAM‐co‐EMA) microgels decreased with increasing incorporation of EMA, but the temperature‐sensitivity was impaired when more EMA was incorporated, causing the volume‐phase transition of the microgels to become more continuous. It is noteworthy that incorporation of moderate amounts of EMA could not only lower the VPTT but also enhance the temperature‐sensitivity of the microgels. The reason for this phenomenon could be attributed to changes in the complicated interactions between the various molecules. Copyright © 2004 Society of Chemical Industry  相似文献   

18.
The graft polymerization of methyl methacrylate and butyl acrylate onto poly(vinyl chloride‐co‐vinyl acetate) with atom transfer radical polymerization (ATRP) was successfully carried out with copper(I) thiocyanate/N,N,N,N,N″‐pentamethyldiethylenetriamine and copper(I) chloride/2,2′‐bipyridine as catalysts in the solvent N,N‐dimethylformamide. For methyl methacrylate, a kinetic plot of ln([M]0/[M]) (where [M]0 is the initial monomer concentration and [M] is the monomer concentration) versus time for the graft polymerization was almost linear, and the molecular weight of the graft copolymer increased with increasing conversion, this being typical for ATRP. The formation of the graft polymer was confirmed with gel permeation chromatography, 1H‐NMR, and Fourier transform infrared spectroscopy. The glass‐transition temperature of the copolymer increased with the concentration of methyl methacrylate. The graft copolymer was hydrolyzed, and its swelling capacity was measured. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 183–189, 2005  相似文献   

19.
To improve the mechanical properties of poly(vinyl chloride) (PVC), the possibility of combining PVC with elastomers was considered. Modification of natural rubber (NR) by graft copolymerization with methyl methacrylate (MMA) and styrene (St) was carried out by emulsion polymerization by using redox initiator to provide an impact modifier for PVC. The impact resistance, dynamic mechanical analysis (DMA), and scanning electron microscopy (SEM) of St and MMA grafted NR [NR‐g‐(St‐co‐MMA)]/PVC (graft copolymer product contents of 5, 10, and 15%) blends were investigated as a function of the amount of graft copolymer product. It was found that the impact strength of blends was increased with an increase of the graft copolymer product content. DMA studies showed that NR‐g‐(St‐co‐MMA) has partial compatibility with PVC. SEM confirmed a shift from brittle failure to ductility with an increase graft copolymer content in the blends. The mechanical properties showed that NR‐g‐(St‐co‐MMA) interacts well with PVC and can also be used as an impact modifier for PVC. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1666–1672, 2004  相似文献   

20.
Blending polypropylene (PP) with biodegradable poly(3‐hydroxybutyrate) (PHB) can be a nice alternative to minimize the disposal problem of PP and the intrinsic brittleness that restricts PHB applications. However, to achieve acceptable engineering properties, the blend needs to be compatibilized because of the immiscibility between PP and PHB. In this work, PP/PHB blends were prepared with different types of copolymers as possible compatibilizers: poly(propylene‐g‐maleic anhydride) (PP–MAH), poly (ethylene‐co‐methyl acrylate) [P(E–MA)], poly(ethylene‐co‐glycidyl methacrylate) [P(E–GMA)], and poly(ethylene‐co‐methyl acrylate‐co‐glycidyl methacrylate) [P(E–MA–GMA)]. The effect of each copolymer on the morphology and mechanical properties of the blends was investigated. The results show that the compatibilizers efficiency decreased in this order: P(E–MA–GMA) > P(E–MA) > P(E–GMA) > PP–MAH; we explained this by taking into consideration the affinity degree of the compatibilizers with the PP matrix, the compatibilizers properties, and their ability to provide physical and/or reactive compatibilization with PHB. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012  相似文献   

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