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合成了两亲性的聚(γ-苄基-L-谷氨酸酯)-b-聚乙二醇(PBLG-b-PEG)聚肽刚-柔嵌段共聚物和聚苯乙烯(PS)均聚物及多种聚苯乙烯衍生物,包括聚(4-乙酰氧基苯乙烯)(PAS)均聚物、聚(4-羟基苯乙烯)(PVPh)均聚物和聚(苯乙烯-co-4-乙酰氧基苯乙烯)(P(S-co-AS))共聚物.用傅里叶变换红外光谱(FTIR)、核磁共振氢谱(1H-NMR)和凝胶渗透色谱(GPC)等表征了聚合物的结构、分子量及分布.采用共溶剂溶解、选择性溶剂透析的方法,制备了PBLG-b-PEG嵌段共聚物与不同PS衍生物(包括PS均聚物)共混体系的自组装聚集体,利用透射电子显微镜(TEM)和扫描电子显微镜(SEM)等表征了自组装体的形貌和结构.研究发现,不同的分子间相互作用(如π-π共轭作用、偶极-偶极相互作用、氢键作用等)对共混体系的自组装形貌有显著的影响.PBLG-b-PEG/PS共混体系自组装可形成表面具有条纹结构的"毛线球"聚集体,该体系中PBLG和PS之间形成π-π共轭作用,相互作用强度相对较弱;PBLG-b-PEG/PAS共混体系自组装可形成表面基本光滑并有轻微凹陷的球形聚集体,该体系中PBLG和PAS之间除了π-π共轭作用,还可形成相对较强的偶极-偶极相互作用;而PBLG-b-PEG/PVPh共混体系自组装得到了囊泡,该体系中PBLG与PVPh之间可形成π-π共轭和氢键作用,相互作用强度进一步增强.对于PBLG-b-PEG/P(S-co-AS)共混体系,可通过改变P(S-co-AS)共聚物中AS摩尔分数和制备温度来调控自组装聚集体表面的条纹形貌.根据PBLG链段与不同PS衍生物(包括PS均聚物)之间不同的分子间相互作用,提出了上述聚集体形貌转变的机理. 相似文献
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采用含时金兹堡-朗道理论(time-dependent ginzburg-landau theory,简称TDGL)方法研究了纳米粒子(nanoparticles,简称NPs)掺杂的两嵌段共聚物/均聚物(AB/C)共混体系在球形受限下的自组装行为.在不同球形受限条件下,两嵌段共聚物/均聚物共混体系形成了多种丰富的形貌,如双螺旋结构、单螺旋结构、层状结构和洋葱环状结构等.当在以上前3种体系中掺杂纳米粒子后,体系结构发生了很大的变化.详细研究了纳米粒子的浓度和浸润强度对以上结构的影响.研究结果表明,通过调控纳米粒子的浓度和浸润性质,该共混体系实现了双螺旋结构→层状结构,单螺旋结构→双螺旋结构,层状结构→单螺旋结构等多种取向序的转变.对于洋葱环状结构,纳米粒子的加入对体系这一结构的影响不大. 相似文献
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应用实空间的自洽平均场理论研究了线性ABC三嵌段共聚物在均聚物C中的自组装. 模拟结果表明, 共聚物在均聚物中形成的分散相主要为核壳结构. 通过降低A与C之间的相互作用, 可以使核壳结构的成核嵌段发生从嵌段A向嵌段B的转变, 并且在转变过程中观察到了多种过渡结构, 包括带有凸起表面的盘状结构和柱状结构以及相互缠绕的柱状结构. 另外, 降低嵌段共聚物中A嵌段在共混体系中的含量有利于形成以B为核的核壳结构. 相似文献
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侧链型偶氮聚电解质自组装和膜结构研究 总被引:5,自引:1,他引:4
研究了4种侧链型偶氮聚电解质的自组装过程及其对自组装膜结构的影响.用聚电解质上的偶氮基团作为“探针”,研究了自组装过程中出现的生色团取向、解吸附和非线性增长等现象.这些侧链型偶氮聚电解质均具有较好的自组装性,但其自组装行为有很大差异.在不同的pH条件下,聚电解质的电离程度不同,导致吸附过程和自组装膜结构亦明显不同.自组装膜的增长和结构取决于体系中吸附和解吸的平衡.偶氮生色团端基的亲水或疏水性对自组装膜的增长有明显的影响.偶氮聚电解质自组装过程不同阶段出现的非线性增长现象,分别反映了基底、溶液性质和聚电解质结构等因素的影响. 相似文献
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聚类肽又称为氮取代聚甘氨酸(N-聚甘氨酸),是一类具有优良生物相容性以及生物活性的可降解高分子材料.由于酰胺键的活泼氢被取代,聚类肽主链结构中消除了聚肽固有的多重氢键相互作用,其主链柔性较好,聚合物性质主要由侧链基团的种类及其物理化学性质决定.基于这种链结构特征,可以通过设计不同的侧基结构,有效地调节聚类肽高分子的热力学性能、降解性能和自组装行为等物理化学性质.合成聚类肽的方法主要有2种——开环聚合和固相合成.本文主要介绍了聚类肽高分子的本体与溶液自组装行为,系统阐明了如何通过调控聚类肽高分子的侧链结构,研究链结构与自组装行为之间的相互关系,进一步构筑具有独特相分离行为以及自组装结构的新型生物高分子,同时探讨了这些材料在生物医用和能源等领域的潜在应用. 相似文献
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在N,N-二甲基甲酰胺/水混合溶剂中制备偶氮聚电解质自组装膜 总被引:1,自引:0,他引:1
利用静电吸附逐层自组装方法在有机溶剂N,N二甲基甲酰胺(DMF)和H2O的混合介质中制备非水溶性偶氮聚电解质自组装多层膜.研究了DMF和H2O的配比对自组装膜生长、结构与表面形态的影响.结果表明,DMFH2O的混合溶剂是非水溶性偶氮聚电解质自组装的理想介质,二者之间的配比对自组装膜的生长速度,膜的结构以及表面形态均有显著影响.随着混合溶液中DMF含量的升高,自组装膜的生长速度逐渐下降但线形生长关系越来越好,所得自组装膜中偶氮生色团的H聚集程度逐渐下降,而且自组装膜的表面越来越平整. 相似文献
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综述了使用计算机模拟方法研究在本体状态下形成柱状结构的线形二嵌段和三嵌段共聚物在平行板间和纳米圆孔内的自组装结构.研究发现,嵌段共聚物体系在受限状态下自组装可以得到与本体状态下不同的纳米结构,调整受限状态的物理化学性质可以调控受限体系的相行为,从而诱导体系形成特定的结构.模拟研究还发现不同相分离强度和链结构的体系,在相同的受限状态下表现出不同的相行为.因此在制备纳米结构材料的研究中,人们要根据嵌段共聚物体系的特定性质,选择相应的受限环境,才能够实现有效的控制. 相似文献
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PLGA-PEG共聚物负载多西紫杉醇的药物输运体系的计算机模拟 总被引:1,自引:0,他引:1
采用耗散粒子动力学模拟的方法研究了抗癌药物输运体系多西紫杉醇与聚乙丙交酯与聚乙二醇的共聚物(PLGA-PEG)的自组装形态, 考察了共聚物浓度、共聚物组成和药物含量等对自组装形态的影响. 模拟结果表明, 不同浓度的PLGA-PEG能够和多西紫杉醇自组装成球状、柱状、层状等结构; 一定的浓度下, 亲水的PEG嵌段将疏水的PLGA嵌段包裹起来形成核壳结构, 可用于疏水药物输运应用. 在比较低的浓度下, 不同组成的PLGA-PEG均会形成球状核壳结构, PEG嵌段较多时壳层较厚核尺寸较小, PLGA嵌段较多时核的尺寸较大但壳层较薄, 综合考虑载药量和稳定性, 模拟结果中PEG嵌段的摩尔分数为60%即PLGA40-PEG60作为载体时性能较佳. 药物的含量对自组装结构也有影响, 药物含量较小时形成球状结构, 药物含量较大时, 则会形成柱状结构. 对PLGA40-PEG60体系, 模拟结果显示药物、聚合物和水的最佳配比为5:10:90. 本工作可为共聚物载药体系的设计与开发提供参考. 相似文献
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The miscibility and structure of A-B copolymer/C homopolymer blends with special interactions were studied by aMonte Carlo simulation in two dimensions. The interaction between segment A and segment C was repulsive, whereas it wasattractive between segment B and segment C. In order to study the effect of copolymer chain structure on the morphologyand structure of A-B copolymer/C homopolymer blends, the alternating, random and block A-B copolymers were introducedinto the blends, respectively. The simulation results indicated that the miscibility of A-B block copolymer/C homopolymerblends depended on the chain structure of the A-B copolymer. Compared with alternating or random copolymer, the blockcopolymer, especially the diblock copolymer, could lead to a poor miscibility of A-B copolymer/C homopolymer blends.Moreover, for diblock A-B copolymer/C homopolymer blends, obvious self-organized core-shell smicture was observed inthe segment B composition region from 20% to 60%. However if diblock copolymer composition in the blends is less than40%, obvious self-organized core-shell structure could be formed in the B-segment component region from 10 to 90%.Furthermore, computer statistical analysis for the simulation results showed that the core sizes tended to increasecontinuously and their distribution became wider with decreasing B-segment component. 相似文献
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Dissipative particle dynamics study on the interfaces in incompatible A/B homopolymer blends and with their block copolymers 总被引:1,自引:0,他引:1
Dissipative particle dynamics, a simulation technique appropriate at mesoscopic scales, has been applied to investigate the interfaces in immiscible binary A/B homopolymer blends and in the ternary systems with their block copolymers. For the binary blends, the interfacial tension increases and the interface thickness decreases with increasing Flory-Huggins interaction parameter chi while the homopolymer chain length is fixed. However, when the chi parameter and one of the homopolymer chain length is fixed, increasing another homopolymer chain length will induce only a small increase on interfacial tension and slight decrease on interface thickness. For the ternary blends, adding the A-b-B block copolymer will reduce the interfacial tension. When the mole number of the block copolymer is fixed, longer block chains have higher efficiency on reducing the interfacial tension than the shorter ones. But for the block copolymers with fixed volume fraction, shorter chains will be more efficient than the longer ones on reducing the interfacial tension. Increasing the block copolymer concentration reduces interfacial tension. This effect is more prominent for shorter block copolymer chains. 相似文献
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Binary blends of a diblock copolymer (AB) and an incompatible homopolymer (C) confined in spherical cavities are studied using a simulated annealing technique. The phase behavior of the blends is examined for four typical cases, representing the different selectivity of the pore surface to the A, B, and C species. The internal morphology of the spherical polymeric particles is controlled by the homopolymer volume fraction, the degree of confinement, and the composition of the copolymer. Inside a particle, the homopolymers segregate to form one or, under some conditions, two domains; thus, the homopolymers may act as an additional controlling parameter of the shape and symmetry of the copolymer domain. A rich array of confinement-induced novel diblock copolymer morphologies is predicted. In particular, core-shell particles with the copolymers as the shell wrapping around a homopolymer core or a copolymer-homopolymer combined core and Janus-like particles with the copolymers and the homopolymers on different sides are obtained. 相似文献
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利用DSC和偏光显微镜等手段研究了部分成核剂对聚丙烯均聚物(PP)、低乙烯含量聚丙烯共聚物及聚丙烯/聚乙烯(PP/PE)共混物结晶行为的影响,结果表明所用成核剂对PP和改性PP具有一定的普适性。聚丙烯共聚物中,由于链结构规整性变差,成核剂的作用显得特别突出,而PP/PE共混物中,由于成核剂向PE相迁移而使其对PP结晶的成核效率降低。 相似文献
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The effects of the chain structure and the intramolecular interaction energy of an A/B copolymer on the miscibility of the binary blends of the copolymer and homopolymer C have been studied by means of a Monte Carlo simulation. In the system, the interactions between segments A, B and C are more repulsive than those between themselves. In order to study the effect of the chain structure of the A/B copolymer on the miscibility, the alternating, random and block copolymers were introduced in the simulations, respectively. The simulation results show that the miscibility of the binary blends strongly depends on the intramolecular interaction energy () between segments A and B within the A/B copolymers. The higher the repulsive interaction energy, the more miscible the A/B copolymer and homopolymer C are. For the diblock copolymer/homopolymer blends, they tend to form micro phase domains. However, the phase domains become so small that the blend can be considered as a homogeneous phase for the alternating copolymer/homopolymer blends. Furthermore, the investigation of the average end-to-end distance () in different systems indicates that the copolymer chains tend to coil with the decrease of whereas the of the homopolymer chains depends on the chain structure of the copolymers. As for the system containing the alternating or the random copolymers, the homopolymer chains also tend to coil with the decrease of . However, for the systems including the block copolymers, there is a slight difference in the of the homopolymer chains with the variation of . 相似文献
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The liquid-crystal assembly of semiflexible-coil diblock copolymers with coil or semiflexible homopolymers is studied by dissipative particle dynamics simulation. Phase diagrams of the blends and orientation ordering parameters among semiflexible blocks are constructed as a function of chain stiffness and homopolymer volume fraction. For semiflexible-coil/coil blends with varying stiffness of semiflexible blocks, we display the rich phase behaviors of the system transited from coil-coil/coil to rod-coil/coil blends. The disorder-lamellae or lamellae-liquid crystalline transition and “dry brush” phenomenon induced by coil homopolymers are observed. For semiflexible-coil/semiflexible blends, adding semiflexible homopolymers also leads to a disorder-order transition and even a transition between monolayer and bilayer smectic-A phase. The results demonstrate that blending homopolymers into semiflexible copolymers can induce liquid-crystal assembly and even improve the orientation ordering of semiflexible blocks effectively. 相似文献
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R. Fayt P. Hadjiandreou Ph. Teyssie 《Journal of polymer science. Part A, Polymer chemistry》1985,23(2):337-342
Poly(butadiene–b–styrene) copolymers containing a pure, 1,4-PB block have been synthesized by a “living” coordination process. The complete hydrogenation of the PB chain leads accordingly to a high-density polyethylene (HDPE) block. The emulsifying efficiency of such a copolymer (H-7) in HDPE/PS blends is compared with that of a previously reported poly(ethylene–butene–b–styrene) copolymer (SE-7) obtained by the PB hydrogenation of an anionically prepared PB–b–PS. Microscopy examinations demonstrate unambiguously the interfacial activity of both copolymers in HDPE/PS blends. The tensile mechanical properties of the blends are significantly but also differently modified by the two emulsifiers. The copolymer H-7 gives rise to the highest strengths, but, contrary to the copolymer SE-7, provides a poor ductility to the blends. This different behavior is assumed to result in part from the different characteristics of the hydrogenated PB blocks. The elastomeric HPB chain of SE-7 should form at the interface a more or less extended soft zone whereas a rigid interface would result from the cocrystallization of the HPB chain of H-7 with the HDPE homopolymer. 相似文献