THE ADSORPTION OF LINEAR POLY(N-ISOPROPYLACRYLAMIDE)CHAINS ON SURFACTANT-FREE POLYSTYRENE NANOPARTICLES

The adsorption of linear poly(N-isopropylacrylamide) (PNIPAM) chains on surfactant-freepolystyrene (PS) nanoparticles was used as a model system to study the hydrophobic adsorption of polymeron the surface, because the hydrophobility of PNIPAM can be continuously varied by a small temperaturechange. The adsorption was investigated by a combination of static and dynamic laser light scattering (LLS)measurements, In static LLS, the absolute excess scattered light intensity led to the amount of PNIPAMadsorbed on the surface. In dynamic LLS, the hydrodynamic thickness of the adsorbed PNIPAM layer wasaccurately measured. For a given particle concentration, the adsorption increases as thc PNIPAMconcentration and the incubation temperature increase. The average density of the adsorbed PNIPAM layer isreciprocally proportional to the number of the PNIPAM chains on the surface, revealing a simple scaling ofthe chain density distribution. The adsorption follows the Langmuir's isotherm. The enthalpy changeestimated from the adsorption at 25℃and 30℃is slightly positive, indicating that the adsorption involvesthe coil-to-globule transition of the chains on the surface.     

聚N,N-二乙基丙烯酰胺蒙脱土纳米复合物的合成及溶胀性能

在制成钠基蒙脱土的基础上 ,对蒙脱土进行了改性 ,并把改性后的蒙脱土分散在N ,N 二乙基丙烯酰胺水溶液中进行聚合 .结果表明这种蒙脱土插层聚合的水凝胶的低温溶胀性能大大提高 ,其对水的释放曲线在特定的温度下也由S形转变为近一直线形 .由于蒙脱土的改性 ,在蒙脱土和聚合物之间的界面化学发生了改变 ,用X衍射分析表明此水凝胶是纳米复合材料 .而加入蒙脱土量达 10 %的水凝胶的溶胀比和温度响应性能也都发生很大改善 .     

聚丙烯酸丁酯-四氢呋喃稀溶液性质

<正> 聚丙烯酸酯是一类具有优良性能和广泛用途的高分子材料。为了探讨材料性能与分子结构的关系,我们用小角激光光散射法、膜渗透压法、稀溶液粘度法及高效体积排斥色谱法研究了聚丙烯酸丁酯的(PBA)稀溶液性质。订定了聚丙烯酸丁酯在四氢呋喃中的极限粘数-分子量关系式。估算了分子的无扰尺寸与热力学参数。证明该聚合物与聚苯乙烯在所用的色谱条件下符合流体力学体积普适标定关系。     

聚N,N-二乙基丙烯酰胺低聚物水溶液的分子动力学研究

对50个单元构成的聚N,N-二乙基丙烯酰胺(PDEA)低聚物的水溶液体系进行了分子动力学的研究,分别模拟了300 K时的伸展链、310 K时的伸展链以及紧缩链与水构成的体系,对溶液中PDEA周围溶剂水分子的分布情况以及水分子形成氢键的情况进行了统计,结果表明在PDEA周围的水产生了比本体水更有序的结构,形成了更多的氢键,这种有序结构维持到第二水合层甚至更远.发生相分离后,PDEA与水分子形成的氢键大部分未被破坏,水合层中每个水分子形成的氢键数也没有明显变化,但水合层(形成有序结构的水分子)内水分子数目的减少使得总的氢键数目减少,从而造成体系能量增加及熵增加.同时还研究了聚合物及水分子的自扩散系数,表明PDEA影响周围水分子结构的同时,对水的动力学性质也产生了很大影响.     

P(NIPAM-co-NVP)共聚物分子链水溶液中的可逆聚集研究

用溶液聚合方法合成了线型聚(N-异丙基丙烯酰胺-co-N-乙烯基吡咯烷酮)共聚物,通过弹性光散射(elastic light scattering,ELS)、荧光光谱与动态光散射研究了共聚物水溶液分子链可逆聚集的温度和时间依赖性.研究表明,升温时,ELS强度增加,分子链聚集;降温时,ELS强度降低,聚集的分子链解离.荧...     

聚醚酰亚胺/酚酞型聚醚醚酮共混体系相容性的稀溶液粘度法研究

<正> 近年来,有关高性能树脂聚酰亚胺共混物的研究日益引起人们的关注。已经发现许多种分子结构不同的聚酰亚胺之间,聚酰亚胺与聚苯并咪唑,或聚醚醚酮能形成完全相容的共混体系,从而扩大了高性能树脂聚酰亚胺的应用范围。 酚酞型聚醚醚酮(PEK-C)是由我所研究开发出的一种新型的聚醚醚酮类高性能树脂,它具有良好的可溶性,优异的机械强度和加工流动性,已广泛应用于结构材料及复合材料的制备。为进一步扩大该树脂的应用范围,本实验室在PEK-C共混物的研究做了大量的工作。本工作研究了聚醚酰亚胺(PEI)/PEK-C共混体系的相容性。PEI和PEK-C的分子结构如下:     

PROPERTIES OF DILUTE SOLUTIONS OF HYDROPHOBICALLY MODIFIED POLY (4-VINYL PYRIDINE) (POLYSOAPS)

Hydrophobically modified poly(4-vinyl pyridines) by alkyl bromides arekinds of polysoap similar to the surfactant. Properties of dilute solutions were studiedthrough the viscosity measurements in pure water and NaCl solutions. In aqueous solu-tions of polysoaps hydrophobic interaction can be attributed to aggregation of hydrophobicgroups of the polysoap main chains. The hydrophobic groups of polysoap can aggregate toform hydrophobic microdomains (micelles) in aqueous solution. This is a compact confor-mation. The formation of such microdomains is a process of dynamic equilibrium.     

聚苯乙烯/顺丁橡胶共混过程中的相结构

利用激光背散射装置结合密炼机对聚合物共混过程进行了在线分析．以典型完全不相容体系聚苯乙烯／顺丁橡胶为共混体系，对不同共混速度下结构参数随共混时间及共混条件如剪切速率等的变化进行了详细讨论．利用扫描电镜与激光背散射在线分析对聚合物共混过程结构参数变化进行了比较，结果显示聚苯乙烯／顺丁橡胶共混物处于熔融态与处于固态时结构基本相同．     

聚四氟乙烯和聚二甲基硅烷的链尺寸和偶极矩

基于改进的旋转异构态方法,推导了对称双取代基高分子链的均方回转半径和均方偶极矩公式,用于研究聚四氟乙烯(PTFE)、聚二甲基硅烷(PDMS)和聚乙烯(PE)链构象依赖的性质.计算得到长链聚四氟乙烯PTFE4(四态模型)和PDMS的构型参数值分别为0.44·mol0.5·g-0.5和0.43·mol0.5·g-0.5,PDMS链的相应温度系数值-7.32×10-3K-1,它与PTFE和PE的值(约-1.00×10-3K-1)相差较大.得到长链PTFE和PDMS的均方电偶极矩特征比结果都很小,如PDMS链的特征比为0.27,说明虽然PTFE和PDMS的侧基键C—F和Si—CH3都有强极性,但其聚合物却是非极性的电介质,具有较好的电绝缘性能,可见高分子链的构象和结构也对聚合物极性和电学性质有很大的影响.得到短链PTFE和PDMS(重复单元x10)均方偶极矩表现出明显的端点效应,特征比随x的改变而呈现明显的波动,这与Flory等的计算结果一致.     

聚(N-异丙基丙烯酰胺)水凝胶微球体积相变的研究

窄分散的聚（Ｎ 异丙基丙烯酰胺）水凝胶微球用乳液聚合方法制备，并用动态和静态光散射对其体积相变进行了研究．与水中聚（Ｎ 异丙基丙烯酰胺）线性单链比较，水中凝胶微球的体积相变温度较高，对温度的响应比较平缓．相变是连续的，有别于大块凝胶非连续的体积变化．在体积相变过程中，凝胶微球始终是密度均一的热力学稳定球体．从相变过程网络密度的变化可以确定，绝大部分的水在收缩过程被排了出来，但在紧缩的凝胶微球中仍含有约７０％的水．     

FORMATION OF MOLYBDENUM OXIDE NANOSTRUCTURES CONTROLLED BY POLY(ETHYLENE OXIDE)

 Polymeric systems have played an important role as structure-directing agents and in the control of nucleation and growth of crystals. This article reviews the work of our research group in the field of the polymer-assisted crystallization of inorganic materials, mainly focused on the formation of highly ordered, porous molybdenum oxide nanostructures. Different experimental parameters including the influence of poly(ethylene oxide)-containing polymers on the morphology and structure of the products obtained from peroxomolybdate solutions are examined. Our electrochemical investigations on molybdate species are also briefly described. Finally, the importance of the precursor species in the formation of the final product is discussed.     

FORMATION OF MOLYBDENUM OXIDE NANOSTRUCTURES CONTROLLED BY POLY(ETHYLENE OXIDE)

Polymeric systems have played an important role as structure-directing agents and in the control of nucleation and growth of crystals.This article reviews the work of our research group in the field of the polymer-assisted crystallization of inorganic materials,mainly focused on the formation of highly ordered,porous molybdenum oxide nanostructures.Different experimental parameters including the influence of poly(ethylene oxide)-containing polymers on the morphology and structure of the products obtained...     

微量聚四氢呋喃-聚甲基丙烯酸甲酯/聚四氢呋喃共混体系稀固体溶液中共聚物胶束的抑制成核作用

本工作将Leibler、Whitmore和Mayes等近期关于非晶嵌段共聚物共混体系胶束理论应用于结晶嵌段共聚物共混体系的熔融态,对聚甲基丙烯酸甲酯-聚四氢呋喃两嵌段共聚物与聚四氢呋喃均聚物共混体系的结晶行为进行了研究.结果表明,很低的共聚物浓度(如1％),其胶束在共混体系的结晶过程中即可显著地起到抑制成核的作用.这对改善结晶均聚物的形态及性能有一定的应用价值.     

微量聚四氢呋喃-聚甲基丙烯酸甲酯/聚四氢呋喃共混体系稀固体溶液中共聚物胶束的抑制成核作用

 本工作将Leibler、Whitmore和Mayes等近期关于非晶嵌段共聚物共混体系胶束理论应用于结晶嵌段共聚物共混体系的熔融态,对聚甲基丙烯酸甲酯-聚四氢呋喃两嵌段共聚物与聚四氢呋喃均聚物共混体系的结晶行为进行了研究.结果表明,很低的共聚物浓度(如1％),其胶束在共混体系的结晶过程中即可显著地起到抑制成核的作用.这对改善结晶均聚物的形态及性能有一定的应用价值.     

THE VISCOELASTIC EFFECT ON THE FORMATION OF MESO-GLOBULAR PHASE OF DILUTE HETEROPOLYMER SOLUTIONS

Linear homopolymer chains in poor solvent exist either as individual crumpled single chain globules or asmacroscopic precipitate, depending on whether the solution is in the one- or the two-phase region. However, linearheteropolymer chains in dilute solution might be able to form stable mesoglobules made up of a limited number of chains ifthe degree of amphiphilicity of the chain is sufficiently high and the experimental conditions are appropriate. The self-assembly of block copolymers in a selective solvent is typical of such examples. In practice, the formation of stablemesoglobules can be directly related to the formation of novel polymeric nanopaticles in solution. In this article, we willaddress the formaton of mesoglobular phase not only on the basis of thermodynamics, but also from a kinetic point of view,which leads to the discussion of how viscoelasticity can affect the phase behavior of heteropolymer chains in dilute solution.The formation and stabilization of several different kinds of novel polymeric nanopedicles will be used to illustrate ourdiscussion.     

羧化聚苯醚与聚苯乙烯共混体系相分离初期分子量影响的光散射研究

本文用激光光散射方法研究了具有特殊相行为[(低临界溶解温度(LCST),高临界溶解温度(UCST)共存]共混体系羧化聚苯醚和聚苯乙烯在UCST域内的不稳相分离初期分子量对动力学参数的影响。结果表明:相分离初期动力学过程与Cahn理论吻合;随着分子量增加,表现扩散系数D_(a??)明显减小;该体系的表现扩散系数为10~(-14) cm~2s~(-1)数量级。deGennes管子模型可很好地描述不稳相分离初期大分子扩散行为。     

N,N′-亚甲基双丙烯酰胺与4-乙烯基吡啶共聚微凝胶的γ-射线辐照合成

通过γ 射线辐照技术 ,在稀水溶液中实现了N ,N′ 亚甲基双丙烯酰胺 (Bis)与 4 乙烯基吡啶 (4 VP)的无皂乳液共聚 ,得到平均流体力学半径 (Rh)为 5 6～ 15 2nm的一系列微凝胶 ,并通过红外光谱、热分析、透射电镜进行了表征 .通过测定Rh、吸光度、凝胶比 ,研究了与Bis共聚的单体及比例、剂量和剂量率对微凝胶合成的影响 .结果表明 ,微凝胶的大小可以通过吸收剂量、单体相对含量的改变来进行控制 .最后 ,对微凝胶的形成机理进行了初步探讨 .     

N,N＇-亚甲基双丙烯酰胺与4-乙烯基吡啶共聚微凝胶的γ-射线辐照合成

通过γ-射线辐照技术,在稀水溶液中实现了N,N＇-亚甲基双丙烯酰胺(Bis)与4-乙烯基吡啶(4-VP)的无皂乳液共聚,得到平均流体力学半径(Rh)为56～152 nm的一系列微凝胶,并通过红外光谱、热分析、透射电镜进行了表征.通过测定Rh、吸光度、凝胶比,研究了与Bis共聚的单体及比例、剂量和剂量率对微凝胶合成的影响.结果表明,微凝胶的大小可以通过吸收剂量、单体相对含量的改变来进行控制.最后,对微凝胶的形成机理进行了初步探讨.     

MEAN-SQUARE RADIUS OF GYRATION AND DIPOLE MOMENT OF POLY(METHYLPHENYLSILOXANE) CHAINS

The mean-square radius of gyration ,the mean-square dipole moment ,the mean-square end-to-end distance and their temperature coefficients of unsymmetrical disubstituted poly(methylphenylsiloxane) (PMPS) chains, as a function of stereochemical structure,confomational energies and length of polymers,were studied by using an improved configurational-confomational statistical method based on the rotational-isomeric-state theory.It is found that the increase in isotacticity of PMPS chains caus...     

酪蛋白氢氧化钠稀溶液的粘度研究

酪蛋白(casein)的溶液性质由于其重要的工业应用价值吸引了广泛的关注,但是在以往酪蛋白稀溶液的粘度研究中忽略了界面效应对粘度测定的影响[1~8],而界面效应对大分子稀溶液粘度行为的巨大作用已得到证实并日益受到重视[9~12].本文研究了20~45℃之间酪蛋白氢氧化钠稀溶液的粘度