Graft copolymerization ofN‐vinyl‐pyrrolidone and acrylamide on cellulose derivatives: synthesis,characterization and study of their biological effect

Graft copolymers of carboxymethyl cellulose and hydroxyethyl cellulose with N‐vinyl‐2‐pyrrolidone and acrylamide have been synthesized by grafting copolymer of N‐vinyl‐2‐pyrrolidone and acrylamide onto a mixture of carboxymethyl cellulose and hydroxyethyl cellulose by a solution polymerization technique using a redox initiation system. The graft copolymers were characterized by ¹³C‐NMR spectroscopy and scanning electron microscopy. These graft copolymers have been tested for their biodegradability and biological activity. None of the graft copolymer solutions shows any microbial degradation up to 10 days. The reported results are evidence of the possibility of anti‐fungi effect. Copyright © 2002 John Wiley & Sons, Ltd.     

Amphiphilic Graft Copolymers of Hydroxypropyl Cellulose Backbone with Nonpolar Polyisobutylene Branches

The novel amphiphilic graft copolymers with hydrophilic hard polar hydroxypropyl cellulose(HPC) backbone and hydrophobic soft nonpolar polyisobutylene(PIB) branches have been successfully synthesized through nucleophilic substitution reaction of living PIB chains carrying oxonium ions with the-OH groups along HPC backbone. The PIB branch length in the graft copolymers could be designed by living cationic polymerization and the grafting density could be adjusted by PIB~+/-OH molar ratio. The living PIB chains carrying oxonium ion were prepared by transformation of allyl bromide end groups in the presence of AgClO_4 and silver nanoparticles(3.2±0.3 nm, 0.7 wt%-1.8 wt%)generated in situ from AgBr. The phase-separation morphology was formed in the graft copolymers due to their incompatibility between backbone and branches. The hydrophilicity on the surface of graft copolymer films could be turned to hydrophobicity by increasing grafting density or/and length of PIB branches. The soft PIB segments in graft copolymers provided an unique surface via self-assembly for anti-protein adsorption against bovine serum albumin. A small amount of Ag nanoparticles in the copolymers contributed to good antibacterial activities against Staphylococcus aureus or Escherichia coli.     

含氟两亲接枝共聚物的制备及其结晶行为

采用大分子单体技术合成了一系列以聚乙二醇为支链、甲基丙烯酸六氟丁酯为主链的含氟两亲接枝共聚物(PHFMA-g-PSPEG)。用1HNMR和凝胶色谱(GPC)对制备的大分子单体和两亲接枝共聚物的结构进行了表征。利用示差扫描量热法(DSC)、X射线衍射(XRD)和偏光显微镜(POM)测试技术对含氟两亲接枝共聚物的结晶行为进行了研究。DSC和XRD结果表明,随着共聚物中含氟链段质量分数的增加,其结晶温度(Tc)和结晶度(Xc)均降低,而结晶熔融温度(Tm)先减小后增加。POM发现,随着共聚物中含氟链段质量分数的增加,其结晶速度减慢,共聚物形成清晰球晶的能力减弱,当共聚物中含氟链段质量分数为57%时,含氟两亲接枝共聚物已不能形成清晰的球晶。     

富含纤维素类农作物秆与丙烯酸接枝共聚制备高倍率吸水树脂

用棉花秆、麦秆和玉米秆等富含纤维素类农作物秆与丙烯酸接枝共聚制备了高倍率的吸水树脂. 研究了不同水质(去离子水、自来水及雨水)对接枝产物吸水性能的影响. 采用棉花秆、麦秆、玉米秆与丙烯酸的接枝产物对去离子水的吸水倍率分别为930, 790和630 g/g, 对自来水的吸水倍率分别为670, 350和250 g/g, 用玉米秆/地瓜淀粉混合物制备的接枝产物对雨水的吸水倍率为540 g/g. 为棉花秆、 麦秆及玉米秆等富含纤维素的农作物秆的深加工与应用开辟了一条途径.     

Ceric-initiated polymerization onto polyacrylonitrile with carbohydrate end groups. Graft versus block copolymer formation

Starch-g-polyacrylonitrile (starch-g-PAN) copolymers were prepared by ceric ammonium nitrate initiation, and the major portion of the starch in these graft copolymers was then removed by acid hydrolysis to yield PAN with oligosaccharide end groups. Although these PAN-oligosaccharide samples reacted with methyl methacrylate in the presence of ceric ammonium nitrate, the resulting products were largely graft copolymers rather than the expected PAN-poly(methyl methacrylate) (PMMA) block copolymers. The following evidence is presented for a PAN-g-PMMA structure: (i) PAN without oligosaccharide end groups also produced a copolymer with methyl methacrylate under our reaction conditions. (ii) Starch-g-PAN (51 or 37% add-on) was a less reactive substrate toward ceric-initiated polymerization than PAN with oligosaccharide end groups. (iii) Low-add-on (18%) starch-g-PAN reacted with methyl methacrylate to give a final graft copolymer in which a large percentage of PMMA was grafted to the PAN component rather than to starch.     

Radiation-induced graft polymerization of acrylic acid onto fluorinated polymers. II. Graft copolymer–metal complexes obtained by radiation grafting onto poly(tetrafluoroethylene-ethylene) copolymer

A study has been made on the graft copolymers obtained by radiation-induced grafting of acrylic acid onto poly(tetrafluoroethylene-ethylene) (ET) films. The conversion of the graft copolymer into metal acrylate copolymer complex was carried out by treatment with different metal salts. Such a prepared graft copolymer–metal complex was confirmed by different methods: IR, UV spectrometry, degree of coloration, and x-ray fluorescence. Some selected properties of the graft copolymer–metal complexes such as electrical conductivity, swelling behavior, and mechanical properties were investigated. The influence of metal complexes in the graft copolymers was determined and compared with the grafted films. The possibility of the practical uses for such prepared graft copolymer–metal complexes was discussed and determined. It was assumed that such materials may be of great interest in the field of semiconducting materials in addition to their applicability as cation-exchange membranes. © 1993 John Wiley & Sons, Inc.     

Relationships of graft polymerization of vinyl monomers onto cellulose. Reaction kinetics and polymer structure

Graft polymerization of acrylamide and sulfuric salt of 2-methyl-5 vinylpyridine onto cellulose using CO(III) salts was studied. It was shown that graft polymerisation of water-soluble polymers can be described by general relationships of radical reaction. The relation between elementary reaction constants of the formation and termination of active centers in cellulose, as well as relation between constants of the propagation, transfer and termination of chains were determined for different cellulose materials and monomers. The translational diffusion, sedimentation, viscosity, and flow birefringence of copolymers have been investigated in different solvents. Experimental data showed that the copolymers obtained are graft copolymers with two to five grafted chains onto macromolecules. The minimum distance between the branch points is 100 ± 20 glucoside units. The peculiarity of these copolymers is relatively low polydispersity. The conformation of macromolecules of such copolymers in solution depends on the compatibility of the copolymer components and the thermodynamic properties of the solvent.     

聚环氧乙烷-g-聚己内酯两亲性接枝共聚物的合成及药物释放行为

通过环氧丙醇(GL)与环氧乙烷(EO)的阴离子顺序开环聚合制备了水溶性嵌段共聚物PEO-b-PGL, 以PGL嵌段每个重复单元的侧羟基为引发点进一步引发ε-己内酯(CL)的开环聚合, 合成了结构规整的以聚环氧乙烷(PEO)为主链的两亲性接枝共聚物(PEO-b-PGL-g-PCL). 研究了PEO-b-PGL-g-PCL在水相中的自组装行为, 采用稳态荧光探针法测定了胶束的临界胶束浓度(cmc). 以疏水性药物阿霉素(DOX)为模型药物, 研究了两亲性接枝共聚物的化学组成对药物的扩散释放以及降解释放行为的影响.     

两性纤维素接枝共聚物的研究Ⅰ. 两性共聚物的合成

用过硫酸铵和四甲基乙二胺氧化还原引发体系合成了羧甲基纤维素接枝甲基丙烯酸二甲胺基乙酯两性共聚物（ＣＧＤ）,研究了反应温度、ｐＨ、原料羧甲基取代度、引发剂用量、反应物料配比和外加盐对接枝共聚的影响,并用红外光谱对接枝共聚物结构进行了鉴定     

Graft copolymerization of methyl methacrylate onto curdlan

Graft copolymerization of methyl methacrylate onto curdlan was first investigated. In the graft copolymerization initiated by ammonium persulfate (APS) in DMSO under a homogeneous condition, the resulting graft copolymers had low molecular weights and low grafting percentages. However, the initiation by APS in water gave graft copolymers having relatively higher molecular weight ( ) and higher grafting percentage (548%) than those copolymers obtained by the homogeneous condition. When the graft copolymerization was carried out by cerium (IV) ammonium nitrate-HNO₃ initiation, the graft copolymer had the highest grafting percentage of 1620% without degradation of the curdlan backbone. The resulting graft copolymers were soluble in DMSO. The graft copolymers obtained by the cerium salt had narrow molecular weight distributions () compared with those by the APS catalyst in DMSO or water. The graft copolymers decomposed with sulfuric acid to isolate PMMAs, which molecular weights were larger than that of the corresponding homo-PMMAs. The structure of the grafted copolymers was characterized by IR, ¹³C NMR, DSC, and SEM. It was found that the graft copolymers exhibited the glass transition temperature (T_g), though curdlan had no T_g. As the grafting percentage increased, the T_g increased to reach 270°C, which was higher than the decomposition temperature of curdlan. The surface image of the grafted copolymers observed by SEM, showed smoothless compared with that of curdlan. It was also revealed that the graft copolymers having the grafting percentage of 1620% swelled in common organic solvents up to 4.5 times of the weight of the dry graft copolymer to form gels. © 1996 John Wiley & Sons, Inc.     

Biodegradable Cellulose Block Copolymers

Biodegradable polymers can be prepared by the incorporation of cellulose oligomeric blocks into the polymer backbone. Block copolymers prepared by reacting equimolar amounts of depolymerized cellulose triacetate (CTA) with MDI or TDI and block terpolymers prepared by reacting the CTA oligomer with poly (propylene glycol) capped with MDI or TDI were deacetylated and incubated with cellulysin at pH 5 and 50 °C. The intrinsic viscosity of each copolymer decreased substantially even after 10 hr incubation time. There was negligible acid hydrolysis. Cellulose showed a smaller decrease at the same incubation time-probably due to its lower accessibility. Methods for incorporating cellulose oligomeric blocks and other biodegradable blocks into different types of polymers are discussed.     

聚苯乙烯大单体与丙烯酸丁酯接枝共聚物的微观分相与表面性能研究

研究了以大单体技术合成的不同侧链长度的苯乙烯与丙烯酸丁酯的接枝共聚物的侧链长度对其微观分相与表面性能的影响,发现仅当聚苯乙烯侧链分子量大于5900时,才可能发生部分微观相分离,分离后对其表面性能影响不明显。临界表面张力r_c虽有差异,但色散力部分y_s^D的计算值却较一致,与所用参照液无关。实验证实,接枝共聚物的表面几乎全被低表面能的聚丙烯酸丁酯骨架所复盖,呈现出明显的表面富集现象。     

Photoinduced Graft Copolymerization. V. Graft Copolymerization of Methyl Methacrylate onto Cellulose in the Presence of N-Bromosuccinimide as Initiator

Abstract

The photoinduced graft copolymerization of methyl methacrylate onto cellulose was studied using N-bromosuccinimide as the photoinitiator. The formation of graft copolymer increases with an increasing amount of cellulose. The graft copolymerization increases with increasing initiator concentration up to 1,25 × 10^?2 M and thereafter it decreases. The percentage of graft increases with increasing monomer concentration up to 46.9 × 10^?2 M and thereafter it decreases. The percentage graft-on increases with increasing temperature. The overall activation energy was computed to be 8.40 kcal/mol. The percentage graft was investigated using different water-miscible organic solvents. The graft copolymerization was also investigated using differently modified cellulose. A possible mechanism for the photo-graft copolymerization onto cellulose is suggested.     

Graft Copolymers from Natural Polymers Using Free Radical Polymerization

The present research work deals with the surface modification of natural cellulosic polymers to develop novel materials for different applications. Natural cellulose-graft-poly (methyl acrylate) copolymers were prepared using the free radical induced graft copolymerization technique. Different reaction parameters were optimized to achieve the highest percentage of grafting of natural cellulose-graft-poly (methyl acrylate) copolymers. The natural cellulose graft copolymers were characterized by FT-IR, SEM, TGA, and physicochemical studies. For the evaluation of swelling and the physicochemical mechanism, swelling and chemical resistance studies were carried out in different solvents as well as chemicals.     

Nanocrystallization-locked Network of Poly(styrene-b-isobutylene-b-styrene)-g-Polytetrahydrofuran Block Graft Copolymer

Poly(styrene-b-isobutylene-b-styrene) triblock copolymer(SIBS), a kind of thermoplastic elastomer with biocompatibility and biostability containing fully saturated soft segments, could be synthesized via living cationic copolymerization. A novel poly[(styrene-comethylstyrene)-b-isobutylene-b-(styrene-co-methylstyrene)]-g-polytetrahydrofuran(M-SIBS-g-PTHF) block graft copolymer was prepared to increase the polarity and service temperature of SIBS by grafting polar PTHF segments onto SIBS. A serie...     

二醋酸纤维素 -聚乙二醇接枝共聚物的核磁共振表征

用^1H NMR和^13C NMR核磁共振技术研究了二醋酸纤维素和聚乙二醇的接枝反应,并确定了^1H NMR和^13C NMR谱中各谱峰的归属,为证明二醋酸纤维素和聚乙二醇的接枝反应提供了依据。     

温敏两亲性接枝物PAM-g-PNIPAm的合成及表征

以巯基乙胺为分子量调节剂,以丙烯酰氯作为链端转化剂合成了不同分子量的端丙烯酰胺基聚(N-异丙基丙烯酰胺)(PNIPAm)大分子单体;与丙烯酰胺共聚合,合成了以PNIPAm为侧链的接枝聚丙烯酰胺.用FTIR和¹HNMR方法表征了接枝聚合物与大分子单体的组成.该接枝聚合物在水溶液中具有热缔合特性及明显的温敏增稠性,水溶液的粘度在32～50℃之间随温度增加而增加.     

活性正离子聚合及原位制备聚醋酸乙烯酯-g-聚四氢呋喃共聚物/纳米银复合材料

通过将烯丙基溴/高氯酸银引发体系引发四氢呋喃活性正离子开环聚合与"grafting onto"合成方法相结合,原位制备了不同接枝密度和接枝链长度的新型聚醋酸乙烯酯-g-聚四氢呋喃接枝共聚物(PVAc-g-PTHF)及其与纳米银(Ag)的复合材料.采用傅里叶变换红外光谱(FTIR)、核磁共振波谱(1H-NMR)和多角度激光光散射-黏度-凝胶渗透色谱仪(MALLS-VIS-GPC)分别表征了该接枝共聚物的化学结构、共聚组成、分子量、分子量分布、接枝支链数目及支化度,采用原子力显微镜(AFM)、示差扫描量热分析(DSC)、偏光显微镜(POM)研究了接枝共聚物中接枝支链数目及支链长度对其微观形态、单端受限链段结晶行为的影响,并探讨了该纳米复合材料的抗菌性能.结果表明:所制备的不同支链数目和支链长度的PVAc-g-PTHF/Ag纳米复合材料,均表现出良好的抗菌性能;接枝共聚物PVAc-g-PTHF的重均分子量可达4.52×10~5,分子分子量较窄(M_w/M_n~1.8),支化因子可达0.19.接枝共聚物PVAc-g-PTHF可形成明显的相分离结构,其微观形态与接枝支链数目有关;相比相同分子量的双端不受限的PTHF链,PVAc-g-PTHF接枝共聚物中单端受限PTHF支链的结晶速率明显降低;在确定接枝支链数目的情况下,随着支链中PTHF链段长度增加,其结晶逐渐增强,结晶熔融温度及熔融焓均稍有增加.     

Graft Copolymerization of Pyrrolidone onto Copolymers of N-Acryloyl Pyrrolidone and Vinyl Monomers

The copolymerizations of N-acryloyl pyrrolidone (NAP) with vinyl monomers methyl methacrylate (MMA), acrylonitrile (AN) and acrylamide (AA) were carried out in dimethylformamide at 65°C using 2,2′-azobisisobutyronitrile(AIBN) as an initiator. The resulting copolymers were used as a polymeric initiator of the anionic graft copolymerization of 2-pyrrolidone. The percent grafting of 2-pyrrolidone onto vinyl copolymer backbone chain involving N-acyllactam groups was found best with copoly(NAP-co-MMA) when the KOH concentration was 0.03 M. The presence of crown ether increased the viscosity of graft copolymers and accelerated the initial rate of anionic graft copolymerization.     

Graft polymerization of 2-hydroxyethyl methacrylate via ATRP with poly(acrylonitrile-co-p-chloromethyl styrene) as a macroinitiator

Amphiphilic graft copolymers are excellent additives for the development of antifouling membranes by nonsolvent induced phase separation. We report a convenient approach to the synthesis of novel graft copolymers with hydrophobic polyacrylonitrile (PAN) backbones and hydrophilic poly(2-hydroxyethyl methacrylate) (PHEMA) side chains. Atom transfer radical polymerization (ATRP) of 2-hydroxyethyl methacrylate was carried out with poly(acrylonitrile-co-p-chloromethyl styrene) (PAN-co-PCMS) as a macroinitiator in the presence of CuCl/2,2’-bipyridine at 50 °C in dimethyl sulfoxide. Kinetics of the graft polymerization was also evaluated. The synthesis of poly(acrylonitrile-co-p-chloromethyl styrene-g-2-hydroxyethyl methacrylate) (PAN-co-(PCMS-g-PHEMA)) can be relatively controlled when CMS (the ATRP sites) unit in the macroinitiator is around 5 mol%. Both the macroinitiators and graft copolymers were characterized by FTIR, NMR and GPC. The surface morphology and wettability of the copolymer films were studied by AFM and water contact angle measurement, respectively. We demonstrate that phase segregation between the PAN-co-PCMS backbones and the PHEMA side chains takes place and the surface hydrophilicity of the graft copolymers increases with the length of the PHEMA side chains. Because these amphiphilic graft copolymers can be synthesized in mass, they will be useful as latent additives for the fabrication of advanced PAN separation membranes.