苯乙烯/丁二烯嵌段共聚物的氟烷基化改性

氧化物;苯乙烯/丁二烯嵌段共聚物的氟烷基化改性     

低催化剂用量ATRP制备丙烯酸酯三嵌段共聚物及性能研究

采用单体摩尔量0.02%的低浓度二价铜盐和廉价配体五甲基二乙烯三胺(PMDETA)络合物为催化剂的ARGET ATRP法,以双官能团引发剂引发丙烯酸丁酯(BA)聚合得到大分子引发剂Br-PBA-Br,研究了温度和催化剂用量对聚合反应速率和可控性的影响.再用氯化铜为催化剂,以Br-PBA-Br引发甲基丙烯酸甲酯(MMA)的ARGET ATRP聚合,得到窄分布的PMMA-b-PBA-b-PMMA三嵌段共聚物,并采用硅藻土对聚合产物进行微量残留铜盐脱除处理,使铜离子含量降到了聚合物质量的0.001%.凝胶渗透色谱(GPC)测得三嵌段共聚物的数均分子量在51000~110000,分布指数低于1.50.核磁共振氢谱(1H-NMR)测得产物共聚组成与GPC结果相近.示差扫描量热仪(DSC)、原子力显微镜(AFM)和动态力学分析(DMA)证明三嵌段共聚物呈现良好的相分离.力学性能测试表明,所得三嵌段共聚物的拉伸强度在2.7~11.7 MPa之间,断裂伸长率在124%~231%之间.采用ARGET ATRP可以合成组成和性能连续可调的PMMA-b-PBA-b-PMMA三嵌段共聚物,同时解决了催化剂用量大,不易脱除的问题.     

PLA/PEG/PLA三嵌段共聚物载药纳米胶囊的制备及表征

用于药物控释体系的微胶束具有实心微球结构,药物分子主要吸附于微球表面,极易脱落,在释药初期有明显的突释效应;而微胶囊的药物主要集中于囊心部分,药物通过扩散作用以及高分子膜的降解而逐渐释放到环境中,因而更有利于药物分子平稳、缓慢地释放．对于自然界中能够自发形成微胶囊的小分子材料,其分子中往往具有一个较小的亲水部分和一个相对较大的憎水部分,     

嵌段共聚物纳米结构设计的计算机模拟研究

嵌段共聚物在本体或在选择性溶剂中可以通过微相分离或自组装形成各种各样的纳米结构,如层状相、球状、棒状及碟状胶束、双层膜、囊泡、纳米管等.这些纳米结构在药物输送、微电子学、先进材料等领域具有令人瞩目的应用前景.因此,研究嵌段共聚物形成纳米有序结构的过程以及理解复杂纳米结构的形成机理具有非常重要的意义.由于嵌段共聚物纳米聚...     

嵌段共聚物调控纳米粒子自组装的研究进展

嵌段共聚物和纳米粒子复合纳米材料具有优异的性能,在生物医药、光电材料、催化材料等领域具有很大的应用价值,已成为备受关注的研究热点.利用嵌段共聚物自组装能够形成特定形态的纳米结构聚集体,将纳米粒子选择性的分布和定位于嵌段共聚物聚集体中,可以改善纳米粒子的性能及其应用.本文综述了近年来实验上利用自组装制备嵌段共聚物-纳米粒子复合纳米材料的方法,并总结分析了影响纳米粒子在嵌段共聚物聚集体中的分布和定位的各种因素,包括纳米粒子的大小、形状及其表面化学.最后总结了嵌段共聚物-纳米粒子的自组装在理论模拟方面的研究.     

聚酯-聚醚多嵌段共聚物的共聚改性

高硬段含量和高软段分子量的聚酯-聚醚多嵌段共聚物有明显的组成不均一性,可分离出大量高熔点的氯仿不溶组份.通过和5mol%间苯二甲酸二甲酯(DMI)共聚,可改进其表观组成均一性,得到不含氯仿不溶物和力学性能优良的硬段含量为40wt%、软段分子量为4000的聚对苯二甲酸乙二酯-聚乙醇醚多嵌段共聚物(PET-PEG).另一合成途径是以间苯二甲酸(IPA)酸解 PET,再和端羟基聚乙二醇醚共缩聚,也可制得相应的改性 PET-PEG.降低聚醚分子量可以有效地改进其组成均一性.     

从三嵌段共聚物制备纳米空心纤维的研究

近年来 ,利用分子自组装技术制备纳米材料已引起人们越来越多的兴趣[1] ,而从三嵌段共聚物在选择性溶剂中形成可分散的纳米颗粒并通过化学改性的方法使其具有某种功能或用作功能化的载体更具有实际意义 [2 ] .本文从由阴离子聚合得到的窄分布三嵌段共聚物出发 ,成功地制备了纳米空心纤维 ,将有可能用于制备纳米导线及模板聚合等方面 .1　实验部分1 .1　样品制备　采用阴离子聚合方法制备三嵌段共聚物 ,用凝胶色谱测定分子量分布宽度 ,光散射测定重均分子量 ,NMR测定其化学组成比 .将共聚物的甲苯浓溶液 (质量分数 30 % )倒入培养皿中并密…     

经两亲嵌段共聚物自组装制备纳米胶束

本文介绍两亲嵌段共聚物的合成,综述了经两亲嵌段共聚物自组装制备纳米胶束的研究进展,并对该领域的发展趋势进行了展望。     

温敏性嵌段共聚物纳米胶束的制备及其稳定性

通过N-异丙基丙烯酰胺(NIPAAm)和N,N-二甲基丙烯酰胺(DMAAm)在链转移剂巯基乙醇存在下的自由基共聚,制备了具有端羟基的共聚物P(NIPAAm-co-DMAAm).利用其端羟基在异辛酸亚锡催化下引发己内酯开环聚合,得到了两亲性嵌段共聚物P(NIPAAm-co-DMAAm)-b-PCL,并在聚己内酯(PCL)链末端引入可光催化反应的不饱和双键.通过1H-NMR、GPC和相转变温度(LCST)等方法对聚合物进行了结构表征,测定了嵌段共聚物形成胶束的临界胶束浓度和胶束粒径,比较了核交联前后胶束的粒径和稳定性.结果表明:通过调节共聚物的组成,可获得LCST在40℃附近的胶束,胶束经核交联后,粒径有所减小,但稳定性明显提高,可用于对药物的温敏控制释放.     

基于ATRP技术的多嵌段共聚物研究进展

原子转移自由基聚合(ATRP)技术是合成结构规整性聚合物的有效途径。综述了近十年来采用ATRP技术合成多嵌段共聚物的研究进展。从引发剂、共聚单体和反应条件等方面讨论了ABA型、ABC型和ABCBA型等类型多嵌段共聚物的合成、性质与潜在应用。对原子转移自由基聚合技术在合成功能性多嵌段共聚物中的应用前景进行了展望。     

Structural and Mechanical Properties of Polybutadiene-Urethane Elastomer

A series of polyurethanes based on hydroxyl-terminated polybutadiene (HTPBD) and cured with Bis-(-hydroxy ethyl)-terephthalate (BHET) have been synthesized. Mechanical, microscopic and kinetic studies were carried out to elucidate the structure-property relationships from the view point of phase separation. We studied the effects of the polymerization method, varying the hard to soft segment ratio and changing the hard-segment domain structure on the properties of the subject materials. Dynamic mechanical responses showed that the Tg of the soft-segment at ?60°C was independent of the hard-segment content, which indicates that the copolymers were well phase separated. A higher hard-segment content brought about a slight increase in the modulus, a moderate increase in the tensile strength and a decrease in the ultimate elongation. The size of the hard-segment domain, as estimated from electron micrographs, ranged from 60A to 100A. It was observed that a higher content of hard-segments causes an increase in the hard-segment domain size. In addition, a general survey of the reaction rate indicated that BHET is less reactive with diphenyl methyl diisocyanate (MDI) than with HTPBD.     

热塑性弹性体/蒙脱土纳米复合材料的制备及性能

热塑性弹性体;蒙脱土;纳米复合材料;动态硫化     

Maleic Anhydride Polyethylene Octene Elastomer Toughened Polyamide 6/Polypropylene Nanocomposites: Mechanical and Morphological Properties

A series of polyamide 6/polypropylene (PA6/PP) blends and nanocomposites containing 4 wt% of organophilic modified montmorillonite (MMT) were designed and prepared by melt compounding followed by injection molding. Maleic anhydride polyethylene octene elastomer (POEgMAH) was used as impact modifier as well as compatibilizer in the blend system. Three weight ratios of PA6/PP blends were prepared i.e. 80:20, 70:30, and 60:40. The mechanical properties of PA6/PP blends and nanocomposite were studied through flexural and impact properties. Scanning electron microscopy (SEM) was used to study the microstructure. The incorporation of 10 wt% POEgMAH into PA6/PP blends significantly increased the toughness with a corresponding reduction in strength and stiffness. However, on further addition of 4 wt% organoclay, the strength and modulus increased but with a sacrifice in impact strength. It was also found that the mechanical properties are a function of blend ratio with 70:30 PA6/PP having the highest impact strength, both for blends and nanocomposites. The morphological study revealed that within the blend ratio studied, the higher the PA6 content, the finer were the POEgMAH particles.     

稀土复合弹性材料的制备和力学性能

利用稀土醇盐与季铵盐化的吡啶改性丁苯橡胶乳液反应,制备含稀土ＰＳＢＲ胶片,然后与天然橡胶并用,获得含稀土复合材料弹性材料发现其物理力学性能有明显提高。通过红外光谱、差示扫描热量计以及交联密度分析,讨论了其结构与性能的关系。     

Synthesis and Properties of Novel Thermal Stable Thermoplastic Poly(ester-imide-ether) Elastomers Based on N,N′-Bis(2-carboxyethyl)-3,3′,4,4′ Biphenyltetracarboxylimide Unit with Excellent Mechanical Properties

A series of thermoplastic poly(ester-imide-ether) (PEIE) elastomers, with different ratios of soft/hard segment 85/15, 80/20 and 70/30, were prepared from 1, 4-butanediol (BD), poly(tetramethylene glycol) (PTMG) and imide dicarboxylic acid monomer based on 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA) and glycine (GLY). The chemical structures of the imide dicarboxylic acid and PEIEs were characterized by FT-IR and ¹H-NMR, respectively. The intrinsic viscosities, thermal properties and mechanical properties of these PEIEs were investigated. The results show that introduction of imide group endows the PEIEs with excellent thermal stability, the melting point of PEIEs at about 220°C, and the temperature of 5% weight loss appears at the range of 332–358°C. In addition, the mechanical properties of PEIEs are also improved with the increment of imide units, the maximum stress and strain reached to 17.15 MP and 1043.75%, respectively.     

聚氨酯弹性体力学性能影响因素探讨

研究了合成方法、原料的种类与配比、硫化工艺条件等因素对聚氨酯弹性体力学性能的影响。结果表明,聚氨酯弹性体的结构与组成以及由此引起的微相分离程度的变化是影响弹性体性能的重要因素。对于同样的聚合多元醇、二异氰酸酯及扩链剂合成的弹性体,采用不同的硫化及熟化条件其力学性能不同,并找到达到最佳力学性能所需的工艺条件。     

Binary Modification of Eucommia ulmoides Gum Toward Elastomer with Tunable Mechanical Properties and Good Compatibility

Eucommia ulmoides gum (EUG) was applied in blend rubber with a heavily limited amount because of its duality of rubber and plastic, and an efficient way of triazolinedione (TAD)‐based Alder‐ene reaction was used to improve the elastic properties of EUG. Binary modification of EUG with two TADs containing hexyl and polyhedral oligomeric silsesquioxane (POSS) groups were conducted to generate the modified EUG elastomers with tunable mechanical properties and good compatibility by varying TAD contents. When the low hexyl (1%) and POSS (0.2%) TADs incorporated, the modified EUGs displayed high tensile strength of 36.57 MPa with the elongation at break of 876%, and thus high toughness of 152.14 MJ m^?3. If high contents of hexyl (20%) and POSS (0.2%) TADs employed, the modified EUGs exhibited excellent elongation at break of 1165% and recovery rate of 60%, and especially its loss factor reached up to 0.83?0.65 at 20?70°C. Therefore, the modified EUGs containing the polar urazole and POSS groups should be a novel elastomer with good compatibility, wear resistance, and damping properties. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019     

Effect of Epoxidation of Diene Component of SBS Block Copolymer on Morphology and Mechanical Properties

In this work, the polybutadiene (PB) block of an asymmetric lamellae forming polystyrene/polybutadiene based triblock copolymer was epoxidized to different extent in order to study its effect on morphology and mechanical behaviour of the copolymer. The products were analyzed by means of different microscopic techniques, Fourier transform infrared (FTIR) spectroscopy and microhardness measurements. It was found that the microphase separation behavior and hence the mechanical properties of the materials were drastically altered through epoxidation of the diene block of the styrene/diene triblock copolymer. With the increase in the extent of epoxidation the lamellar structure changed to distorted lamellae and then to disordered domains. Consequently, inhomogeneous mechanical performance of the samples was observed at higher degree of chemical modification.