丙烯酸酯类与亚麻纤维接枝共聚反应的研究

Abou-Zeid等人曾报道以Fe(~2+)-H_2O_2体系引发丙烯腈等单体与黄麻纤维的接枝共聚反应,Misra等人报道了以S_2O_8_2-TU为引发体系,甲基丙烯酸甲酯与黄麻纤维的接枝共聚,最近,我们报道了以Ce(Ⅳ)引发甲基丙烯酸甲酯、丙烯酸乙酯(EA)分别与苧麻及亚麻纤维的接枝共聚。亚麻纤维与丙烯酸酯类单体接枝改性后,仲长率有所提高,加强了结合力,改善了成纱品质,因此引起人们的重视。本文以过硫酸钾-硫脲(KPS-TU)为引发体系,研究丙烯酸甲酯(MA)、EA及丙烯酸丁酯(BA)与亚麻纤维的接枝共聚反应规律,用IR、SEM、X射     

环状单体与乙烯基单体的杂化共聚

本文研究了在膦腈碱(t-BuP4)催化下各种环状单体和乙烯基单体的杂化共聚,发现己内酯、丙交酯或环碳酸酯与丙烯酸酯或甲基丙烯酸酯能够进行杂化共聚,但环硅氧烷与乙烯基单体、丙烯腈与内酯不能杂化共聚.研究表明,单体与活性中心的匹配决定了杂化共聚能否进行.     

乙烯基单体在炭黑表面上的接枝聚合

讨论了分别在铈离子体系，正丁基锂体系，过渡金属离子乙酰丙酮铜（Ⅱ）以及焦磷酸络锰（Ⅲ）体系的作用下，炭黑与乙烯基单体的接枝聚合．研究了引发剂浓度、单体浓度、反应时间对接枝聚合反应的影响．利用ＦＴ ＩＲ分析确证了炭黑表面的接枝反应，利用ＴＥＭ表征了接枝炭黑的形态．结果表明，在所研究的多种炭黑表面接枝聚合体系中，正丁基锂体系的接枝率最高，可达２００％．而各种氧化还原体素的接枝率只能达到３０％左右．表面接枝后的炭黑在介质中的分散稳定性明显改善．     

大分子单体及其规整接枝共聚物

论述了通过活性阴离子聚合、活性阳离子聚合、基团转移聚合、自由基聚合、缩聚等途径合成各种大分子单体,论讨了大分子单体的表征,并结合自己的工作综合介绍近年来大分子单体共聚的进展及其规整接枝共聚物的纯化和特性。     

玻璃纤维表面的乙烯基单体接枝聚合

用玻璃纤维表面处理剂ＭＡＣ处理玻璃纤维后，再进行臭氧处理，使玻璃纤维的表面产生活性中心，引发苯乙烯、甲基丙烯酸甲酯、及丙烯酸等乙烯基单体在玻璃纤维表面上接枝聚合。接枝纤维的密度减小，对水的浸润性下降，红外光谱及扫描电镜观察证明玻璃纤维表面上接枝聚合物的存在。     

聚苯乙烯大单体与乙酸乙烯酯的共聚及其接枝共聚物的表征

 研究了聚苯乙烯大单体与乙酸乙烯酯的溶液聚合,结果表明,接枝效率随引发剂用量、聚合温度及小单体与大单体的投料比的增加而增加,随大单体的分子量增加而减少,而随单体浓度的变化呈现一最大值。共聚过程中大单体的转化率开始较小单体的增加快,后期变慢。用萃取法纯化的接枝共聚物经GPC、IR、¹H-NMR及PGC等表征,并算得平均接枝数为4—7。透射电镜表明接枝共聚物中存在微观相分离。     

罗布麻纤维与丙烯酸酯类接枝共聚物结构和性能的研究

本文以氧化还原体系引发丙烯酸甲酯(MA)、丙烯酸乙酯(EA)、丙烯酸丁酯(BA)与罗布麻纤维的接枝共聚反应,用IR、SEM和X-射线衍射等手段表征了接枝纤维的结构。与纯罗布麻纤维相比较,接枝纤维具有较高的断裂伸长率和较低的杨氏模量,柔顺性增加;耐酸、碱能力随接枝率的增加而提高,但吸湿率不降。     

纤维素与己内酰胺的接枝共聚反应

以过硫酸铵和过硫酸钾为引发剂,在碱性环境下进行纤维素与己内酰胺的接枝共聚反应.采用红外光谱仪(FT-IR)、扫描电子显微镜(SEM)及X射线衍射仪(XRD)对接枝共聚物的分子结构、表观形貌和结晶性进行了表征.通过单因素实验重点考察了单体用量、引发剂浓度、反应温度和反应时间等对接枝共聚物接枝率的影响.结果表明:以3 g纤...     

铬酸引发丙烯腈与苎麻纤维接枝共聚反应

棉、麻类织物通过与乙烯类单体接枝共聚可以提高染色性、皱折回复性、耐磨性、防污性等［‘j．纤维素接枝共聚物的合成始于50年代，目前研究最多的是乙烯类单体通过自由基活性中间体与纤维素进行接技共聚，但此法存在一个突出的问题是在接技共聚的同时生成大量均聚物．铬酸（下文用Cr’“表示）是公认的强氧化剂，据报道［’－‘j，它单独存在时并不能引发乙烯类单体聚合，如果用Cr‘”引发乙烯类单体与纤维素接技共聚，均聚物的生成量将会减少．本文以Cr’”为引发剂，将丙烯睛（AN）与艺麻纤维进行接技共聚，考查不同条件对接技率及均聚…     

稀土金属催化极性乙烯基单体聚合的研究进展

极性乙烯基单体所形成的聚合物侧链上带有极性基团,可以提高聚合物的黏性、表面性能、韧性以及与其他聚合物的相容性等。金属介导的极性乙烯基单体的聚合是合成极性乙烯基聚合物最直接、原子效率最高的方法之一。近年来,一系列结构明确的稀土金属催化剂被开发应用于该领域,取到了许多具有重要意义的研究成果。本文综述了近10年来稀土金属催化极性乙烯基单体聚合的研究进展,按聚合模式分为传统单位点聚合和路易斯酸碱对聚合两类。     

Graft Copolymerization of Vinyl Monomers onto Silk Fibers

Modification of the properties of textile fibers in order to get a fiber of improved textile performance is the subject of study of several groups of scientists and technologists [1–4]. Of the several methods available, grafting promises to be a potentially effective means of altering the fiber properties through the added polymer formed in situ without destroying the basic properties of the parent fiber. Copolymerization is attractive to chemists as a means of modifying macromolecules since, in general, degradation can be minimized. The desirable properties of the polymer are retained and copolymerization provides additional properties through the added polymer. The added polymer may be formed in situ by polymerization of a monomer or monomers, by condensation of reactants, or by the deposition of preformed polymer.     

乙烯基单体/N-取代马来酰亚胺共聚合动力学

详细研究了聚合温度、引发剂用量、单体配比对苯乙烯(St)/N-苯基马来酰亚胺(PMI)共聚合动力学的影响.对St、甲基丙烯酸甲酯(MMA)和丙烯腈(AN)等单一或混合单体与PMI、N-环己基马来酰亚胺(ChMI)和N-邻氯苯基马来酰亚胺(o-CPMI)的共聚合进行了研究,并讨论了单体结构的影响.     

Grafting onto Wool. IX. Graft Copolymerization of Vinyl Monomers by Use of Vanadium Oxyacetylacetonate as Initiator

Methyl methacrylate (MMA), acrylic acid (AAc), and vinyl acetate (VAc) were graft copolymerized onto Himachali wool in an aqueous medium by using vanadium oxyacetyl acetonate as initiator. Graft copolymerization was studied at 45, 55, 65, and 75°C for various reaction periods. The percentage of grafting was determined as functions of concentration of monomers, concentration of initiator, time, and temperature. The maximum percentage of grafting with each monomer occurred at 55°. Several grafting experiments were carried out in the presence of various additives which include HNO3, DMSO, and pyridine. Nitric acid was found to promote grafting of MMA. All these additives had adverse effects on grafting of VAc and AAc. MMA, VAc, and AAc were found to differ in reactivity toward grafting and followed the order MMA > AAc > VAc.     

Graft Copolymerization of Vinyl Monomers onto Cellulose and Cellulosic Materials

Abstract

Graft copolymerization is a novel method which has wide application in synthesizing new forms of polymeric materials and also in modifying the properties of natural polymers [1,2]. Much research has been done on grafting polymeric molecules on to cellulose to produce materials of new properties intermediate between those of cellulose and those of synthetics. A variety of property changes can be imparted to cellulose through grafting without destroying the crystallinity or crystallization potential of the substrate or reducing its melting point. Some of the most dramatic changes in properties which have been brought about by grafting to cellulose are viscoelasticity, stereoregularity, hygroscopicity, water repellency, improved adhesion to a variety of substances, settability, soil resistance, bacteriocidal properties, and thermal stability.     

丙烯酰胺共聚合及产物分散性的研究

采用水溶性引发体系研究了丙烯酰胺的均聚以及与几种乙烯基单体的共聚反应。探讨了引发剂、温度、单体浓度及加热时间对所得聚合物相对分子质量及其分散性能的影响。对产物的结构特性和相对分子质量分布进行了表征,并考察了共聚物的分散性能。丙烯酰胺共聚物同均聚物相比,分散性能有明显的改善。     

Grafting Vinyl Monomers onto Silk Fibers: Graft Copolymerization of Vinyl Monomers onto Silk Using the Vanadyl Acetylacetonate Complex

Abstract

The graft copolymerization of methyl methacrylate (MMA) onto mulberry silk fibers was studied in aqueous solution using the acetylacetonate oxovanadium (IV) complex. The rate of grafting was investigated by varying the concentration of the monomer and the complex, the acidity of the medium, the solvent composition of the reaction medium, the surfactants, and the inhibitors. The graft yield increases with increasing concentration of the initiator up to 8.75 × 10^?5 mol/L, of the monomer up to 0.5634 mol/L, and thereafter it decreases. Among the various vinyl monomers studied, MMA was found to be most suitable for grafting. Grafting increases with increasing concentration of HCIO₄ and with increasing temperature. Inhibitors like picryl chloride and hydroquinone significantly decrease the extent of grafting. Alcoholic solvents at a solvents/water ration of 10:90 seem to constitute the most favorable medium for grafting. A suitable reaction scheme has been proposed, and the activation energy calculated from the Arrhenius plots.     

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.     

甲壳素和壳聚糖的接枝共聚改性

天然高分子甲壳素、壳聚糖由于分子链上大量存在的反应性官能团 ,易于通过自由基引发与乙烯基单体接枝共聚 ,也可与其它高分子链偶合制得接枝共聚物。通过接枝共聚改性 ,可以赋予甲壳素和壳聚糖以某些新的性能 ,扩大了其应用范围。本文对甲壳素、壳聚糖的接枝共聚改性反应进展、机理以及产物的性能等进行了介绍     

壳聚糖接枝共聚改性最新研究进展

壳聚糖是一种天然高分子,也是迄今为止唯一发现的阳离子碱性多糖。壳聚糖分子链中富含羟基和氨基等反应性官能团,具有生物相容性、生物可降解性、抗菌性、无细胞毒性等优良性能,在生化、医药、环保、农业等领域有广泛的应用前景。然而,由于其大分子具有较好的立构规整性和较强的氢键作用,除稀盐酸、稀醋酸外,壳聚糖不溶于水和其它有机溶剂,因而限制了它的应用范围。为了扩大其应用领域,常通过接枝共聚反应来改善壳聚糖的性能。本文介绍了壳聚糖接枝共聚改性的最新研究进展,包括自由基引发接枝法、偶联接枝法以及催化接枝法。