动态流变法在聚合物/聚合物界面分子链扩散研究中的应用

聚合物/聚合物界面的分子链扩散问题在塑料注塑、焊接、共混等领域普遍存在.动态流变法是研究聚合物/聚合物界面分子链扩散的一种有力手段,这种方法对于界面间分子链扩散的监测非常灵敏.本文简述了用动态流变法研究聚合物/聚合物界面扩散的原理、实验方法以及优点,着重讨论了采用该方法研究初始界面分子链末端分布对扩散机理的影响、对称聚合物/聚合物界面分子链扩散的量化,非对称聚合物/聚合物界面的相互扩散,分子量多分散性对聚合物/聚合物界面扩散的影响,聚合物/聚合物界面间的流动和扩散耦合以及近年来动态流变法在化学反应型聚合物/聚合物界面的应用进展.     

从诺贝尔奖看高分子百年*

从高分子学科确立到现在已经经历了整整一个世纪。围绕高分子领域的历次诺贝尔奖,重点回顾了“高分子”概念的确立、高分子合成化学、高分子理论、功能高分子等领域的里程碑事件,分析了高分子学科的未来发展趋势。     

Two-dimensional lattice Monte Carlo simulation of the compatibility of A/B/functionalized A ternary polymer mixtures coupled with chemical reaction

Compatibility of A/B and functionalized A ternary polymer mixtures was studied by Monte Carlo simulation in a two-dimensional lattice. Polymer A was a nonreactive polymer, whereas polymer B was a reactive polymer and immiscible with polymer A. Functionalized polymer A could react with the end group of polymer B, leading to the formation of block copolymers. Simulation results showed the phase domain sizes dropped considerably with increasing functionalized polymer A content, indicating that the compatibility between polymer A and B could be markedly improved with the introduction of functionalized polymer A. Moreover, it was shown that the resulting block copolymers tended to distribute at the phase interface between polymer A and B, and the block copolymer conformation depended on the structures of polymer B and functionalized polymer A. In case 1, i.e., both polymer B and functionalized polymer A were with single end group, it could be found that the block A and block B of resulting A–B copolymer inserted into polymer A and polymer B phase domains, respectively. In case 2, i.e., functionalized polymer A was with single end group and polymer B was with double end groups, it was found that the resulting A–B–A triblock copolymer tended to connect two neighbor separated polymer A phase domains. However, in case 3, namely functionalized polymer A was with double end groups and polymer B was with single end group, it was found that the resulting B–A–B triblock copolymer was likely to form a folding conformation. These lead to the different compatibilizing effects for different polymer structures. Comparing with case 1 and case 2, functionalized polymer A with double end groups (case 3) had less effective to compatibilize the A/B polymer blends. For the purpose of comparison, same simulations were carried out in a three-dimensional lattice. The results showed the compatibility behavior of the mixtures was similar to those in the two-dimensional lattice with the addition of functionalized polymer A. However, the conformation of the resulting block copolymers was different from that in the two-dimensional lattice.     

聚烯烃／极性聚合物界面的分子状态

为了克服高分子共混物界面不易表征的缺点，提出用溶剂选择性溶解方法使界面暴露．结合Ｘ－射线光电子能谱（ＸＰＳ）表征手段，研究了官能化聚合物，接枝型共聚物及带有反应性基团的聚合物作为共混物增容剂时在界面区域的分子状态．实验结果表明，作增容剂时，官能化聚合物在界面区内采取最有利的分子构象，充分发挥增容作用；接枝型共聚物主链、侧链向相应本体聚合物内扩散；而带有反应性基团的聚合物与某个本体聚合物发生反应之前存在反应基团在界面富集的过程     

The effect of polymer chain length and surface density on the adhesiveness of functionalized polymersomes

Giant cell-like polymer vesicles, polymersomes, made from the diblock copolymer poly(ethylene oxide)-polybutadiene (PEO-PBD), have bilayer structures similar to the cell membrane but have superior and tunable properties for storage and stability. We have modified the terminal hydroxyl of the hydrophilic block with biotin-lysine (biocytin), a biologically derived group that imparts specific adhesiveness to a polymer colloid coated with avidin. The functionalized polymer will form vesicles, either on its own or when mixed with unmodified block copolymers that also form vesicles. The incorporation and mixing of the functionalized polymer into vesicle bilayers is measured using a fluorescent version ofbiocytin with confocal microscopy. The fluorescence signal associated with the vesicle is in proportion with the concentration of functional polymer added during vesicle construction. The adhesiveness of polymer vesicles containing functionalized biotinylated polymer to avidin coated microspheres is measured with micropipet aspiration. Two types of polymer vesicles were constructed: one where the functionalized polymer (molecular weight (MW), 10400 Da) was longer than the surrounding unfunctionalized polymer (MW, 3600 Da) and one where the functionalized polymer (MW, 10400 Da) was the same length as the unfunctionalized polymer. In all cases, the avidin-biotin bonds form kinetically trapped crossbridges that impart little tension as they form but require significantly more tension to break. The relative length of the functionalized polymer on the surface of the vesicle is an important determinant for the adhesion of a polymer vesicle but not for the adsorption of soluble avidin. Greater adhesion strengths are seen where the functionalized polymer is longer than the surrounding polymer. The concentration of functionalized polymer at which adhesion is maximal depends on the relative lengths of the polymers. When the functionalized polymer is the same length as the surface brush of the polymersome membrane, the critical tension is maximal at 10 mol % functionalized polymer concentration. However, when the biocytin groups are attached to a polymer which is larger than the surface brush, the critical tension is maximal at 55 mol % functionalized polymer. These results indicate that polymer mixing and length can control the interfacial adhesion of polymer brushes and must be understood to tune polymersome adhesiveness.     

剪切作用对功能聚合物微观结构性能的影响研究

梳型聚合物和活性聚合物是目前常用驱油聚合物,其增黏性和黏弹性是评价其驱油能力的重要指标.为考察剪切作用对两种聚合物溶液性能的影响,分别研究了梳型聚合物和活性聚合物溶液经过模拟炮眼剪切前后的宏观和微观性能变化.结果表明,在高速剪切、拉伸应力作用下,梳型聚合物黏度损失率为40.73%,活性聚合物黏度损失率为70.10%;当剪切频率为0.02 Hz时,梳型聚合物界面扩张弹性降低了19.03%,而活性聚合物界面扩张弹性降低了68.03%;相比活性聚合物,梳型聚合物紧密的空间网状结构虽被部分破坏,但仍有疏松的网络结构,且以聚集体的形式紧密地分散在溶液中,通过DLS及AFM测定表明其粒径尺寸稍有变小;可见梳型聚合物抗剪切能力较活性聚合物强.     

The study of structure formation in a polymer-containing ionic liquid in terms of the integral equation theory

The structural properties of a polymer-containing ionic liquid under the conditions of good solubility of a flexible polymer are studied theoretically. Two systems are discussed: In one, polymer solubility is due to the presence of specific interaction between polymer chains and solvent cations; in the other, polymer solubility is due to the presence of specific interactions between the polymer and solvent anions. The dependences of the structural characteristics of a solution on the polymer concentration and the energy of attraction between polymer chains and solvent ions are calculated. In a semidilute polymer solution, long-range correlations of polymer chains with a power dependence of the characteristic scale of ordering on the polymer density appear. The conditions under which, along with the intermediate ordering typical of a pure ionic liquid, the long-range ordering of the solvent cations and anions occur after addition of a polymer to the ionic liquid are studied.     

Phase transitions of a polymer threading a membrane coupled to coil-globule transitions

We theoretically study phase transitions of a polymer threading through a pore imbedded in a membrane. We focus on the coupling between a partition of the polymer segments through the membrane and a coil-globule transition of the single polymer chain. Based on the Flory model for collapse transitions of a polymer chain, we calculate the fraction of polymer segments and the expansion factor of a polymer coil on each side of the membrane. We predict a first-order phase transition of a polymer threading a membrane; polymer segments in one side are discontinuously translocated into the other side, depending on solvent conditions and molecular weight of the polymer. We also discuss the equilibrium conformation of the polymer chain on each side of the membrane.     

高分子单链的研究进展

随着纳米科技在高分子领域的不断升温,高分子单链凝聚态的研究引起了人们的广泛重视。高分子单链以纳米尺度的微粒孤立存在,不存在分子链之间的几何缠结。本文综述了近年来国内外高分子单链的研究进展。首先介绍了高分子单链的主要制备方法如喷雾法、冷冻干燥法、微乳液聚合法、反向沉淀法以及表面扩展膜法,接着详细介绍了高分子单链的表征技术及高分子链构象的计算机模拟技术,最后介绍了高分子单链及单分子胶束在制备金属纳米粒子领域的应用,并展望了高分子单链的研究领域和方向。     

弱电场驱动下高分子链在周期管道内输运的模拟研究

采用Langevin动力学方法模拟研究了弱电场驱动下高分子链在无限长周期管道中的输运过程. 管道由长度相等的α和β两部分周期排列而成, 其中高分子链与α管道间存在相互吸引作用, 而与β管道间存在纯排斥作用. 模拟结果表明, 高分子链在输运过程中存在明显的受限阶段, 其逃离受限的方式与管道宽度有关且满足不同的规律. 对于窄管道, 高分子链在输运过程中呈直线伸展构型且运动具有“蛇爬行”特征. 高分子链逃离受限过程伴随着整条链的运动, 从而导致迁移率随高分子链长呈周期变化, 而且在迁移率极值位置, 高分子链投影长度与管道半周期之间存在简单的整数倍关系. 对于宽管道, 高分子链在输运过程中出现弯折构型且运动具有“蠕虫运动”特征. 当链长比较长时, 高分子链可通过链前端部分的伸长逃离受限, 从而导致迁移率与高分子链长度无关. 模拟结果可能有助于利用周期管道对不同长度的高分子链进行分离及可控输运.     

再谈“高分子物理”本科阶段教学内容

高分子的特殊性在于其长链结构,特殊的长链结构带来运动的特殊性。本文从"高分子物理"的定义是运动着的高分子物质和高分子物质的运动出发,确定高分子物理的定位是高分子物质的结构、结构演变和各层次结构单元的运动,围绕"高分子物理"的核心本质是长链状结构、长链状结构的演变及各层次长链结构的运动规律,针对本科阶段的任务和特点,阐述教学主要内容是结构和运动,附带相关性能,提出对现行教材内容和编排顺序的建议和想法。     

高聚物从高弹态到流体态的转变

将高聚物由高弹态转变为流体态的转变温度命名为流动温度Tf,该转变温度与高聚物分子量密切相关.在高聚物从高弹态转变为流体态的研究中,由于T1.1的概念忽视对高聚物分子量的依赖性,因此采用Tf的概念更为合理.本文对高聚物的流动温度Tf的讨论涉及高聚物温度-形变曲线、高弹态温区、高聚物熔体剪切粘度.从高聚物凝聚态观点来看,高聚物熔体中凝聚缠结网络中的凝聚结点是分子链的局部向列相互作用使链单元间产生平行凝聚而形成的,而高聚物从高弹态到流体态的转变正是反映了高聚物熔体中凝聚缠结网络的物理交联点,即凝聚结点状态的变化.高聚物熔体可以流动,说明熔体中凝聚网络中的凝聚结点至少是可以在瞬间内打开的,升温使凝聚结点的解凝聚状态存在的时间加长,凝聚状态存在时间减短,当升高到某一温度时,在凝聚结点解凝聚状态的时间内,分子链通过内旋转使质量中心在外加力的方向上可以发生位移,此时高聚物从高弹态转变为流体态,而此时的温度就是流动温度Tf.对高聚物流体弛豫网络的研究,是一个很有前景的研究课题.     

Polymer blends filled with carbon black: structure and electrical properties

Morphology and electrical conductivity of polymer blends based on polypropylene, polyethylene, polyoxymethylene, polyamide 12, co‐polymer ABS filled with carbon black (CB) were studied. When filler is introduced in polymer blend, three cases of filler spatial distribution can be obtained. CB can be distributed randomly within polymer matrix, can be situated in one of the polymer components or can be localized on the boundary of the polymer components. The existence of different cases of filled blends structure is defined by following reasons: thermodynamic factors (relationship between interface surface tensions of polymer‐filler γ_pf and polymer‐polymer surface tension γ_pp); kinetic factors (relationship between viscosities of polymer components); processing factors (methods of the filler introduction in the complex polymer matrix, which can enhance or depress the influence of thermodynamic and kinetic factors).     

Synthesis and Application of Tetracycline Imprinted Polymer

Molecular imprinted polymer was synthesized by polymerization of methacrylate and ethylene glycol dimethacrylate in presence of tetracycline. The prepared polymer exhibited selectivity of 1.8 to 3.9 over non-imprinted polymer depending on nature of solvent. In water, 3.45 mg of tetracycline bind to 1 g of imprinted polymer. Non-covalent interactions between tetracycline and polymer provided selectivity to imprinted polymer. The polymer was evaluated in column chromatography and the bound tetracycline can be eluted with acetonitrile. Ciprofloxacin interacted with imprinted polymer, whereas amoxicillin did not. The feasibility of using MIP for concentrating tetracycline from milk has been demonstrated.     

端基功能化聚合物的表面性能

综述了端基功能化聚合物表面结构与性能的最新研究进展.聚合物端基功能化是实现聚合物表面改性的一种有效技术.通过端基功能化可以精确控制聚合物表面功能基团的种类和数量,从而影响聚合物表面的化学结构与性能.重点论述了功能化端基在聚合物表面的离析现象和产生这一现象的原因,以及功能化端基对聚合物表面分子运动能力的影响.本文还介绍了近年来用于研究端基功能化聚合物表面的表征新技术,如SFG、NR、SSIMS等.对端基功能化聚合物表面的环境响应性也进行了阐述.指出了利用不同功能化端基可以有效地控制聚合物表面的亲疏水性.并对端基功能化聚合物的应用进行了展望.     

聚合物科学进展

本文对2011~2013年我国高分子科学重要研究进展进行了综述。全文分为高分子化学、响应性高分子、高分子物理、高分子组装、超分子聚合物、光电功能聚合物、生物医用高分子、石墨烯/聚合物复合体系、聚合物杂化体系和高分子工程等10部分。近年我国内地学者发表的高分子领域研究论文总量跃居世界第一,论文引用数跃居第二,在诸多分支领域中学科发展水平大幅提高,达到或接近国际水平的研究成果快速增多,国际影响力逐年提高。我国高分子学者通过基础研究,为高分子工业技术水平提升和创新也做出了许多贡献。本文还对本学科前沿、发展趋势进行了介绍与展望。文中共引用了227篇参考文献。     

Analysis of the roles of nitrogen and oxygen in the synthesis of an alcohol polymer during plasma-induced reactions

This paper investigates the roles of nitrogen and oxygen in forming a 1-butanol polymer. The analyses show that nitrogen is the key species for forming a stable 1-butanol polymer, and the viscosity of the polymer is increased as the ratio of nitrogen in the polymer is increased. In contrast, oxygen does not contribute to forming the polymer but rather prevents formation of the polymer instead. This article also analyzes the origin of C=O bonding in the 1-butanol polymer. IR analysis demonstrates that oxygen in the atmosphere is fixed in the polymer as C=O bonds, instead oxidizing the O-H group in 1-butanol.     

高分子固体电解质设计的新概念

高分子固体电解质是开发零释放能源－－高性能电池的关键材料。本文详细介绍了20世纪90年代以来高分子固体电解质结构设计的新概念，包括高分子凝胶电解质，两相高分子电解质，盐掺聚合物（Polymer-in-salt)，有机／无机纳米复合型电解质，悬挂柔性短聚醚侧链的网格聚合物电解质。     

聚合物互通多孔材料的乳液模板法制备及其功能化研究*

本文对近年来利用乳液模板制备聚合物互通多孔材料的研究进行了综述,主要介绍以高内相乳液模板制备互通多孔聚合物整体柱和利用双重乳液 (或称多重乳液) 制备多孔或多空聚合物微球的进展;分析目前多孔聚合物材料研究中存在的问题及其研究动态;讨论合成多孔聚合物材料的性能缺陷及其表面功能化改性的相关研究;并对聚合物互通多孔材料潜在的应用和研究前景进行了展望。     

Synthesis and characterization of monodisperse porous polymer particles

Monodisperse porous polymer particles in the size range of 10 μm in diameter were prepared via seeded emulsion polymerization. Linear polymer (polystyrene seed) or a mixture of linear polymer and solvent or nonsolvent were used as inert diluents. The pore diameters of these porous polymer particles were on the order of 1000 Å with pore volumes up to 0.9 mL/g and specific surface areas up to 200 m²/g. The physical features of the porous polymer particles depended on the diluent type and the crosslinker content, as well as the molecular weight of polymer seed particles. By varying the molecular weight of the linear polymer, monodisperse porous polymer particles with different pore size distribution could be synthesized. Polymer seed with a low degree of crosslinking instead of linear polymer could also be used to prepare monodisperse porous polymer particles with smaller pore volume and pore size.