Dual Relativity and Lorentz Transformations for Liquid-Like Media and Statistics from Scaling Concepts for Geometry

A dual class of Lorentz transformations (dual LT) for linear and Brownian motions in liquid-like media, is presented and discussed. It descends from two LT groups, for self-diffusion in simple liquids (BLT) and its geometrical analogy (GLT), which turned out to represent promising basic tools to deal with statistics at different length scales. Time dilation and length contraction of BLT occur upon ordering the originally indistinguishable molecular disorder in the liquid medium (i.e., a diffusivity lowering), giving rise to universality and scaling laws in polymer solutions. Dual LT exhibit a rich phenomenology, leading to a scale-dependent motion concept, where Brownian and quantum movements somewhat correspond. Density correlations in simple liquids, for instance, are suggested on this basis to behave like radial wave functions at the atomic scale. We also report some remarks on statistics in general, and its connection towards geometry.     

现代高分子物理课程系列漫谈——溶液中高分子单链自由能

高分子单链自由能表达式对于推导及理解高分子尺寸对聚合度的标度依赖关系至关重要,本文提供了一个基于Flory格子模型的推导溶液中高分子单链自由能的新方法。该方法消除了高分子物理教学过程中高分子溶液部分知识点的割裂问题。此外,由该方法得到的单链自由能表达式可将不同性质溶剂(即良溶剂、不良溶剂和θ溶剂)中高分子尺寸与聚合度的标度关系的推导过程统一起来,帮助学生理解各个知识点之间的深层次关系,并由此感受高分子物理之美。     

Structure of the Polymer Obtained from Bisphenol-A and Cl 2 P(O)CH 3

Using the step-by-step build-up approach, the possible conformations of compound PhOP(O)(Me)OPh(Me) 2 Ph were constructed and geometrically optimized. Among the obtained structures 32 conformations belonging to low, comparable energy levels were used to construct the most stable dimers and tetramers of the title polymer. The results allowed us to estimate the geometrical structure of the polymer.     

聚合物液体的状态方程

本文分析介绍了三个最广泛使用的聚合物液体状态方程，Ｆｌｏｒｙ、ＳＬ和ＳＳ方程及作者开发的三个新方程ＳＨＴ、ＳＨＴＦ和ＯＣＭ的理论基础和假设，并用１５个聚合物液体、１７个大分子量烃液体和６个常用有机溶剂的Ｐ－Ｖ－Ｔ数据作了比较。结果表明，ＯＣＭ方程精度最好，其他方程精度按ＳＳ、ＳＨＴ、ＳＨＴＦ、Ｆｌｏｒｙ、ＳＬ依次变差。结论是开放胞腔更接近液体的真实结构，空穴的引入可以改进胞腔理论的计算精度，Ｌ－Ｊ位能可以较好地反映液体中分子间的作用力。     

石英晶体微天平在高分子科学中的应用

固/液界面上高分子的行为直接影响着界面的物理和化学性质.对于高分子在界面的动态行为,由于缺乏有效的手段,检测一直十分困难.最近,一种频率-耗散联用型石英晶体微天平(QCM-D)问世,它能够同时检测固/液界面上有关高分子质量和结构的变化,因而可应用于界面高分子研究的多个方面.本文介绍石英晶体微天平的基本原理,并综述作者实验室最近几年利用QCM-D开展的若干工作,包括固/液界面上高分子链的构象变化,固/液界面上高分子的吸附,高分子降解动力学和聚电解质的"层层组装"等方面.     

《高分子化学》教学中几个概念的梳理

在高分子化学教学中,有一些基本概念常常会引起学生的困惑,如高分子相对分子质量的定义、缩聚反应中残余水量、单体的聚合选择性和醋酸乙烯酯的聚合能力等。根据本人在多年教学过程中所得的体会和认识,对这些基本概念进行了梳理,供同仁们在教学中或学生们在学习过程中参考。     

高聚物双流体配位模型状态方程的简化

对高聚物以流体配位模型状态方程进行了简化，忽略了其中的Ｑ项，以简化的状态方程对４２个纯高聚物（聚丙烯、聚苯乙烯、聚异丁烯和聚丁烯－１），２种纯溶剂（苯，环己烷）和２个高聚物／溶剂混合系（聚异丁烯／苯和聚异丁烯／环己烷）进行关联，结果表明，简化的状态方程与原方程同样具有很好的关联精度和温度适用性。     

6个聚合物胞腔理论状态方程的分子参数比较

利用Ｚｏｌｌｅｒ提供的ＰＢＤ和ＰＩ两种聚合物系列样品的Ｐ－Ｖ－Ｔ数据，对Ｃｅｌｌ、Ｆｌｏｒｙ、ＳＳ、ＳＨＴ、ＳＨＴＦ和ＯＣＭ６个状态方程的分子参数及其随链结构变化的规律作了比较，得到了一些有益的结论。     

基于PSRK模型预测高分子溶液汽液平衡

为了更好地预测高分子溶液的汽液平衡,本文应用PSRK模型改进的混合规则[即将组合项(∑xiInb／bi)与原UNIFAC模型中的组合项(Flory-Huggins项)相抵消所获得的简化的混合规则]来计算方程的能量参数α。为了计入自由体积效应对高分子溶液的过量Gibbs自由能的贡献,在计算体积参bij时,将原混合规则中的指数修订为bij^1/2(bi^1/2 bj^1/2)/2。应用PSRK模型结合改进的混合规则预测二元高分子溶液体系的汽液平衡,结果表明新模型的计算精度是令人满意的。     

通过词义辨析讲透"高分子物理"课程中的基本概念

在"高分子物理"课程教学中,采用对词义相近的名词、基本概念进行辨别分析的方法,讲透基本概念.     

用于聚合物溶液扩散系数计算的活度系数模型比较

用40个聚合物溶液体系的实验数据,对三个有代表性的活度系数模型用于计算联系自扩散系数和互扩散系数的热力学因子的精度进行了比较,结果表明三个模型的精度相近,误差一般在20％左右。,因而本工作揭示了聚合物溶注保由自扩散系数计算与扩散系数的一个潜在问题。即由于活度系数模型计算热力学因子误差较大所带来的较大不确定性。     

Diffusion of Nanoparticles in Semidilute Polymer Solutions: A Multiparticle Collision Dynamics Study

The diffusion of nanoparticles immersed in semidilute polymer solutions is investigated by a hybrid mesoscopic multiparticle collision dynamics method. Effects of polymer concentration and hydrodynamic interactions among polymer monomers are focused. Extensive simulations show that the dependence of diffusion coefficient D on the polymer concentration c agrees with Phillies equation D-exp (-αc^δ) with a scaling exponent δ≈0.97 which coincides with the experimental one in literature. For increasing nanoparticle size, the scaling prefactor α increases monotonically while the scaling exponent always keeps fixed. Moreover, we also study the diffusion of nanoparticle without hydrodynamic interactions and find that mobility of the nanoparticle slows down, and the scaling exponent is obviously different from the one in experiments, implying that hydrodynamic interactions play a crucial role in the diffusion of a nanoparticle in semidilute polymer solutions.     

Diffusion Mode Transition between Gaussian and Non-Gaussian of Nanoparticles in Polymer Solutions

The dynamic density functional theory is applied to study the diffusion of nanoparticles in polymer solutions, in which different diffusion modes have been identified by exploiting the density and free energy evolutions. Under the condition of low polymer concentration, diffusion is controlled by particle free motion with a normal Gaussian type. As the concentration increases, the non- Gaussian behavior can be observed when the particle size is comparable to the correlation length of polymer chain. Particles need to penetrate through a cage and overcome an entropic barrier, where the hopping and the model-coupling diffusion coexist. Further increase of polymer concentration can result in complete restriction of the particle by surrounding polymer segments. In this case, the non-Gaussian process fades away, and particle diffusion is controlled by Rouse dynamics of polymer chains with the generalized Gaussian characteristics.     

大分子溶致凝聚过程中的几个分界浓度

按照现代高分子凝聚态物理学观点,高分子溶液按浓度分为:极稀溶液、稀溶液、亚浓溶液、浓溶液、极浓溶液5个层次,各层次间的分界浓度分别称为动态接触浓度、接触浓度、缠结浓度和全高斯链浓度,其中全高斯链浓度由本文作者命名。文中给出各分界浓度的定义,介绍各分界浓度的物理意义,特别说明命名全高斯链浓度的依据。同时详细讨论了不同浓度溶液中大分子链的构象及其变化、链间相互作用的本质和微观图像、以及溶液浓度变化对溶液性质的影响。     

Conformational Polymer Statistics from the Geometrical Scaling of Monomeric Units and the Characteristic Ratio from Circle Maps. Application to Carbohydrate Macromolecules

Summary: Basic results on conformational chain statistics were formerly derived from scaling concepts for geometry and a relativistic picture of Brownian self‐diffusion in liquids. A polymer conformation was interpreted as a geometrical scaling law of its monomer shape, where the concept of characteristic ratio identifies a mean metric coefficient, originating topologically from rotational degrees of freedom internal to single molecules. Here, we add the former theoretical results to first numerical calculations. They are performed for three polysaccharides, provided with different chain topologies and constrained conformationally to identical square‐well energy states with increasing width. The spatial coil dilation‐contraction has been described satisfactorily by dihedral sine‐like rotations on a circle at dimeric length scales. New intrinsic quantities, like inner characteristic ratio and angular Kuhn step, both belonging to the shape of single molecules, have been finally defined. The geometrical mechanism bringing them at larger scales, to point out the chain shape size, is still unknown and under consideration.

Conformational energy landscape of nigerose.     

A Cleavable Crosslinking Strategy for Commodity Polymer Functionalization and Generation of Reprocessable Thermosets

Covalently crosslinked polymeric materials, known as thermosets, possess enhanced mechanical strength and thermal stability relative to the corresponding uncrosslinked thermoplastics. However, the presence of covalent inter-chain crosslinks that makes thermosets so attractive is precisely what makes them so difficult to reprocess and recycle. Here, we demonstrate the introduction of chemically cleavable groups into a bis-diazirine crosslinker. Application of this cleavable crosslinker reagent to commercial low-functionality polyolefins (or to a small-molecule model) results in the rapid, efficient introduction of molecular crosslinks that can be uncoupled by specific chemical inputs. These proof-of-concept findings provide one potential strategy for circularization of the thermoplastic/thermoset plastics economy, and may allow crosslinked polyolefins to be manufactured, used, reprocessed, and re-used without losing value. As an added benefit, the method allows the ready introduction of functionality into non-functionalized commodity polymers.     

电场条件下高分子共混物组分浓度梯度化的研究

研究了聚乙烯醇/聚丙烯酸高分子共混物水溶液中,共混物各组分在电场诱导条件下沿电场方向的浓度梯度分布情况.通过测定不同时刻PVA/PAA高分子共混物水溶液在电场的不同区域内的pH值,研究了电场诱导下共混物各组分沿电场方向的迁移过程.结果表明,PAAn-向电场正极迁移,同时由于浓差梯度,PVA向负极迁移,并形成浓度梯度分布.随时间的延长,高分子共混物的组分梯度程度逐渐加大.     

Polymer Radii and Moments in the Polycondensation Reaction of A_a Type

For the polycondensation reaction of A. type, the kth radius for k>2 can be expressed in terms of polymer moments.     

聚合物纳米复合体系中聚合物结构及动力学研究进展

从计算模拟及实验角度系统总结了聚合物结构、聚合物构象、聚合物扩散及聚合物多尺度动力学的研究进展,阐述了各影响因素及其变化规律,并对聚合物动力学的未来研究进行了展望.