棉纤维的N-异丙基丙烯酰胺接枝共聚及产物的温敏性研究

以硝酸铈铵(CAN)、过硫酸钾(KPS)及H2O2/H2A(双氧水/抗坏血酸)为引发体系,采用溶液自由基接枝法制备了具有温敏性的棉纤维N-异丙基丙烯酰胺接枝共聚物(cotton-g-PNIPAAm);在上述3种引发剂作用下的接枝反应可以达到的接枝率(G)排序为G(H2O2/H2A)>G(KPS)>G(CAN);研究了其他因素如引发剂浓度、反应时间、反应温度和单体浓度等对接枝率的影响,得出了优化的接枝反应条件;接枝样品的FTIR分析图谱和SEM观察均表明样品表面已接枝了聚N-异丙基丙烯酰胺;DSC分析显示,棉纤维N-异丙基丙烯酰胺接枝共聚物的低临界溶解温度(LCST)与纯的聚N-异丙基丙烯酰胺凝胶(LCST=32.48℃)相似,约为32~33℃;接枝率的变化对试样LCST的影响很小,但其可逆焓变(ΔH)会随接枝率的提高而增加;采用滴水试验法(AATCC 79)和毛效试验法(FZ/T 01071)检测棉纤维的N-异丙基丙烯酰胺接枝共聚物在不同温度时的吸水性变化,显示试样具有温敏特性,其中接枝率介于25%~45%的试样温敏性较高,过低或过高的接枝率均不利于获得高的温敏性;棉纤维的N-异丙基丙烯酰胺接枝共聚物试样的可逆焓变(ΔH)随试样膨胀/收缩时间变化的研究和分析结果表明,棉纤维的N-异丙基丙烯酰胺接枝共聚物对温度变化的响应比纯聚N-异丙基丙烯酰胺凝胶快.     

红外光谱法测定蔗渣微晶纤维素与丙烯酰胺接枝共聚物的接枝率

采用双谱带吸光度比值法测定微晶纤维素—丙烯酰胺接枝共聚物(GCAM)的接枝率,能够消除试片厚度和背景的影响。由元素分析法求得GCAM二元组分的吸收系数比K值。在此基础上,根据接枝共聚物红外吸光度比值R,直接求得GCAM的接枝率。不同物料比的接枝共聚物的接枝率与红外吸光度比值呈现线性关系,发现当物料比W_1/W_2大于2时,接枝共聚物的接枝率达最大值,即使工艺上再增加丙烯酰胺用量,也不能较大提高接枝共聚的接枝率,只能产生更多的丙酰胺均聚物。     

水溶性聚合物和两亲聚合物：聚（丙烯酰胺－co－丙烯酸钠）－g－聚（β－胺基丙酸）接枝共聚物

合成了端丙烯酰胺基聚（β－胺基两酸）大分子单体，用端基滴定法和１Ｈ—ＮＭＲ法测定了大分子单体的分子量，用１３Ｃ—ＮＭＲ和氢氧化钠水解法测定了支化度．在水溶液中用硫酸亚铁／异丙苯过氧化氢氧化还原引发体系引发丙烯酸胺、丙烯酸钠与聚（β－胺基丙酸）大分子单体的共聚反应，合成了聚（丙烯酰胺－ｃｏ－丙烯酸钠）－ｇ－聚（β－胺基丙酸）接枝共聚物．用１Ｈ—ＮＭＲ和滴定法测定了接枝共聚物的组成．溶液性质的数据表明，与部分水解聚丙烯酰胶相比，聚（β－胺基丙酸）含量较高的接枝共聚物具有较好的耐盐性和优异的贮存稳定性．     

壳聚糖-两性聚氨酯接枝共聚物的制备

利用壳聚糖大分子链上的－OH和－NH2基团与两性聚氨酯预聚体的端－NCO基团反应，把两性聚氨酯链接枝到壳聚糖分子链上，为聚电解质及纳米胶体粒子间的组装，复合性质的研究提供模型化合物，红外光谱，热分析方法初步研究表明，采用上述方法能够制备出APU－壳聚糖接枝共聚物，但产物是壳聚糖与接枝共聚物的混合物，研究发现，这种接枝共聚物在盐酸水溶液中呈胶束形态，而且具有独特的流变性。     

CMC-g-DNA接枝共聚物的合成与表征

在磷酸盐缓冲溶液中用1-(3-二甲氨基丙基)-3-乙基碳二亚胺(EDC)与N-羟基琥珀酰亚胺(NHS)活化羧甲基纤维素钠(CMC)侧链上的羧基; 在室温下再将活化的CMC与5'端经氨基修饰的单链脱氧核糖核酸(DNA)齐聚物(ODNs)反应, 获得CMC上接枝ODNs的共聚物(CMC-g-ODNs), 以Lambda DNA为模板, 通过聚合酶链式反应(PCR), 将接枝的ODNs扩增为长度为1300个碱基对的双链DNA, 从而制得CMC侧链上接枝DNA的共聚物CMC-g-DNA. 采用傅里叶红外光谱仪测定CMC与NHS形成的中间体; 用水平式琼脂糖凝胶电泳和垂直板变性聚丙烯酰胺凝胶电泳对CMC-g-DNA接枝共聚物进行表征. 结果表明, 合成了CMC-g-DNA接枝共聚物, 且在酸性条件下CMC的活化效果更好; 同时, 接枝在CMC上的DNA在琼脂糖凝胶电泳中迁移速率加快, 而在聚丙烯酰胺凝胶电泳中迁移速率减慢.     

聚乳酸接枝丙烯酰胺制备抗菌材料

采用自由基接枝聚合法,以过氧化苯甲酰为引发剂,制备聚乳酸接枝丙烯酰胺共聚物;对接枝共聚物进行氯化,制备表面含卤胺基团的抗菌聚乳酸高分子材料.考察了丙烯酰胺含量、引发剂浓度、聚合温度、聚合时间等对接枝率的影响.采用核磁共振氢谱、红外光谱等对接枝聚合物的分子结构进行了表征;利用溶液浇铸法,制备抗菌聚乳酸薄膜,并对薄膜的抗菌性能等进行了研究.结果表明:实验获得的卤胺接枝聚乳酸对大肠杆菌抗菌性能明显.     

壳聚糖与N-异丙基丙烯酰胺接枝共聚凝胶的辐射合成及性能研究

采用γ辐射技术引发壳聚糖与N异丙基丙烯酰胺进行接枝共聚,制备了温度及pH敏感水凝胶.研究了单体浓度、辐射剂量等对接枝率和接枝效率的影响,并用13CCPMASNMR和TG表征了接枝物的结构.研究结果表明,用γ射线引发壳聚糖接枝异丙基丙烯酰胺具有较高的接枝率和接枝效率,接枝的聚合物具有明显的温度及pH敏感的特点.     

羟乙基纤维素/AMPS接枝共聚物与大豆分离蛋白形成聚离子复合物研究

用硝酸铈铵/硝酸(CAN/HNO3)引发了羟乙基纤维素(HEC)与2-丙烯酰胺基-2-甲基丙磺酸(AMPS)的接枝共聚反应.研究了单体浓度、引发剂浓度和反应温度对接枝率的影响.由于强酸型基团磺酸基的引入,接枝共聚物带有了阴离子电荷,在小于大豆分离蛋白等电点(pH=4.5)的缓冲溶液(pH=1.5)中,通过接枝共聚物的阴离子电荷与大豆分离蛋白(SPI)阳离子电荷之间的静电相互作用,可以形成HEC-g-PAMPS/SPI聚离子复合物.以聚离子复合物负载模型药物布洛芬(Ibuprofen),在37℃于不同pH的缓冲溶液中进行了体外释放研究.药物释放速率的测定表明,以HEC-g-PAMPS/SPI聚离子复合物作为布洛芬的载体,可以在选择性条件下实现药物可控释放的目的.     

接枝共聚的接枝参数表述方法的探讨

介绍了接枝共聚物接枝参数，如单体转化率、接枝率、接枝效率、均聚物含量及接枝频率，概述了对这些参数在进行表述淀粉接枝共聚时出现的种各种表达形式。在此基础上，指出了这些其在表达上出现的混乱现象。     

两亲性树状接枝己内酯共聚物的合成与表征

通过树状接枝聚己内酯的侧羟基及端羟基与氯甲酰化的聚乙二醇进行接枝反应,得到带有亲水性聚乙二醇链段的新型两亲性树状接枝共聚物.1H-NMR分析显示,接枝率为50%左右.GPC分析结果表明,共聚物分子量呈较窄的单峰分布,分子量与接枝前相比明显增高.两亲性共聚物能直接分散在水中形成胶束溶液.以芘为荧光探针的测试结果表明其临界胶束浓度有降低.动态光散射测得胶束平均粒径在16至31 nm之间,粒径分散指数适中,PDI在0.25至0.39之间.TEM显示胶束粒子为不规整球形,由更小的粒径为几个纳米的微粒聚集而成,这些微粒的大小刚好与单个大分子的尺寸相匹配.因此,两亲性树状接枝聚己内酯在水相中存在单分子胶束与多分子组装胶束的平衡.得益于支化聚合物结构中的纳米空腔,两亲性树状接枝聚合物胶束对紫杉醇具有优良的包载能力.     

含有机硅多嵌段及其接枝共聚物的表面组成

利用ＸＰＳ对聚二甲基硅氧烷与聚砜或／和聚对羟基苯乙烯组成的二元和三元多嵌段和接枝共聚物及其共混物进行了研究。结果表明溶液成果的聚合物样品的表面都存在有机硅富集，共混物的表面富集程度等于接枝共聚物，更高于多嵌段共聚物，讨论了有机硅含量和键接结构对有机硅表面富集的影响。     

Synthesis,characterization and metal ion sorption studies of graft copolymers of cellulose with glycidyl methacrylate and some comonomers

To develop low-cost and environmentally friendly polymeric materials for enrichment, separation and remediation of metal ions from water, novel reactive graft copolymers based on cellulose extracted from pine needles were synthesized by grafting of poly(glycidyl methacrylate) alone and with comonomers acrylic acid, acrylamide and acrylonitrile by benzoyl peroxide initiation. Structural aspects of graft copolymers have been characterized by elemental analysis, FTIR, and solvent uptake behaviour. An attempt has been made to study sorption of Fe²⁺, Cu²⁺ and Cr⁶⁺ ions on candidate graft copolymers by an equilibration method and to investigate the structural aspects of graft copolymers and establish a relationship between the structural aspects of graft copolymers and metal ion uptake efficiency and selectivity.     

聚苯乙烯大单体与丙烯酸酯接枝共聚物对聚苯乙烯表面的改性研究

研究了由大单体技术合成的侧链为聚苯乙烯、骨架由丙烯酸丁酯或甲基丙烯酸羟乙酯/丙烯酸丁酯组成的接枝共聚物对聚苯乙烯的表面改性效果(试样浇注于玻璃纸上成膜)。发现仅添加0.5wt％的接枝共聚物就可完全改变聚苯乙烯膜两面的临界表面张力γ-c与表面能中的色散力部份γ_s~D,少量添加的接枝共聚物在改性聚苯乙烯膜的两面呈现出明显的表面富集现象。虽然两类接枝共聚物的极性有较大的差异,但改性聚苯乙烯成膜后的自由表面均显示出与聚丙烯酸丁酯相同的低表面能(γ_s~D=37×10~(-3)牛顿·米~(-1)),而添加三元接枝共聚物的改性膜与玻璃纸接触的表面却具有高于聚苯乙烯的表面能|(γ_s~D=54×10(-3)牛顿·米~(-1))。这种改性膜的两面具有不同的表面能是由于接枝共聚物中不同的组分在膜的两面富集所致,已通过ESCA的表面测试结果证实,并与按Gibbs吸附式的计算值相符。     

Complete mapping of the morphologies of some linear and graft fluorinated co-oligomers in an aprotic solvent by dissipative particle dynamics

The mesoscopic morphologies of linear and graft fluorinated block copolymers of ABCBA and C:BA types, respectively, have been investigated by using dissipative particle dynamics method. Self-assembly in a selective solvent has been examined by the introduction of dimethylformamide as the choice of solvent. By comparing the solubility parameters calculated using atomistic simulations, fluorine-containing segments are found to be immiscible both with other segments of the polymer and with the solvent. Morphologies of the pure linear and graft copolymers were lamellar and cylindrical, respectively. Interfacial tension versus concentration curves have been used to explain the self-assembly behavior of copolymers in solution, as well as to predict the kinetic mechanisms responsible for this behavior.     

Water-Soluble Copolymers. II. Synthesis and Characterization of Model Dextran-g-Acrylamides by Ce(lV)/HNO3-lnduced Initiation

In order to develop polymers useful as mobility control agents in enhanced oil recovery processes, water-soluble acrylamide grafted polysaccharide copolymers have been synthesized in water at 25° C using a ceric ammonium nitrate/nitric acid system. The effects of varying concentrations of ceric ion, monomer, and substrate on conversion, graft length, and molecular structure of the reaction products have been examined. The crude reaction products were purified by fractional precipitation and then were analyzed for nitrogen content using a micro-Kjeldahl method. The chemical structures of the graft copolymers were studied by selective hydrolysis of the carbohydrate backbones. Intrinsic viscosity and grafting length data were used to predict solution behavior of the graft copolymers prepared under controlled conditions. Aqueous size exclusion and viscosity studies showed direct correlations between hydrodynamic volume and length of the polyacrylamide side-chain grafts.     

利用大分子单体技术合成接枝共聚物

大分子单体和小分子共单体共聚是合成接枝共聚物的重要途径之一。本文综述了大分子单体通过各种聚合方式(自由基共聚、离子型共聚、配位共聚、基团转移共聚和逐步共聚)和普通小分子单体的共聚反应,详细讨论了大分子单体和小分子单体的自由基共聚反应动力学,并简要介绍了接枝共聚物的应用背景。     

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.     

SYNTHESIS AND CHARACTERIZATION OF AMPHIPHILIC GRAFT COPOLYMER CONTAINING MICROPHASE SEPARATED AND LONG POLY(ETHYLENE OXIDE) SIDE CHAIN STRUCTURES**

Acryloyl terminated Poly (ethyleneoxide)macromonomers (PEO-A) with different PEO chain lengths have been prepared by deactivation of PEO alkoxide with acryloyl chloride. A new kind of amphiphilic polystyrene-g-poly (ethylene oxide)graft copolymer containing both microphase separated and PEO side chain structures has been synthesized from radical copolymerization of PEO-A macromonomer with styrene. After careful purification by a newly-developed method called "selective dissolution', the well-defined structure of the purified copolymers was confirmed by IR, ~1H-NMR and GPC. Various experimental parameters controlling the copolymerization were studied in detail. The results indicated that the feed ratio of styrene to macromonomer(S/M) was the most important determining factor for the composition of the copolymers. A detailed "comb- model" was proposed to describe the molecular structure of the graft copolymers. Finally, this amphiphilic graft copolymers may readily form microphase separated structures as clearly indicated by transmission electron microscopy.     

Water Soluble Dextran-Polyacrylamide Graft Copolymers for Capturing Metal Ions

Summary: The graft copolymers of Polyacrylamide (PAA) to Dextran (M_w = 20000 and M_w = 70000) have been synthesised by ceric-ion-reduced redox initiation method. Molecular characteristic of graft copolymers were determined from light scattering, SEC, and viscometry data. It was established that the increase of molecular weight of Dextran component up to 3.5 times do not influence essentially organization at molecular level of these copolymers in aqueous solution. Thet D-g-PAA copolymers capable of binding the heavy metal ions.     

Synthesis of IONP's decorated graft copolymers and study of their magnetic force–induced wastewater treatment

Our work is focused on facile synthesis and modification of amylopectin‐grafted block copolymers by using reversible addition?fragmentation chain transfer (RAFT) polymerization technique. This technique yields polymers with controlled molecular weight and low polydispersity indexes and is feasible with a wide range of monomers. Five different grades of amylopectin‐grafted polymethacrylic acid and polyacrylamide block copolymers have been synthesized via RAFT, by varying the amount of acrylamide employing amylopectin‐based macro chain transfer agent. Graft copolymers have been upgraded as smart responsive graft copolymers, through the incorporation of iron oxide nanoparticles (IONPs) via condensation reaction. The polymeric materials have been extensively characterized by energy‐dispersive X‐ray analysis, Fourier transform infrared spectroscopy, proton magnetic resonance spectroscopy, scanning electron microscopy, ultraviolet‐visible spectroscopy, gel permeation chromatography, transmission electron microscopy, thermogravimetric analysis, and X‐ray diffraction analysis. Normal and responsive graft copolymers have been studied for removal of model contaminant (kaolin), and responsive graft copolymers have been used to remove methylene blue dye (without using any adsorbent) from water by applying external magnetic field. The upgraded block copolymers have shown best performance in wastewater treatment.