St-DVB微凝胶星型两性接枝共聚物的单分子膜性质研究

用自由基引发苯乙烯-二乙烯基苯(St-DVB)共聚合成了带有大量乙烯基的活性微凝胶,再将此活性胶核与甲基丙烯酸(MMA)共聚制得微凝胶星型两性聚合物,并成功地制备了LB膜,此微凝胶星型两性聚合物LB膜与-般典型LB膜的区别在于它的疏水部分不是长脂链,而是分子量比较大的苯乙烯-二乙烯基苯微凝胶;此疏水的微凝胶核与亲水的聚甲基丙烯酸链在气-液界面上形成类似"浮萍"结构的单分子膜,因而在诸多方面表现出特异性质。     

不同结构Iniferter引发苯乙烯聚合反应的研究

以不同结构的含氯化合物与铜试剂反应合成了4种链引发-转移-终止剂(Iniferter)。研究了它们引发苯乙烯的聚合反应过程,重点考察了Iniferter结构对聚合产物的影响。采用核磁共振氢谱和凝胶渗透色谱对聚合物分子量和分子量分布进行了测定。结果表明:Iniferter结构对聚合反应速率、分子量实测值与理论值间的对应关系及分子量分布均有明显影响,当其形成的初级自由基上带有使其稳定的基团时,引发效率就高,聚合反应速率较快,而且分子量理论值与实测值两者更接近。加入四甲基秋兰姆化二硫组成双组份Iniferter引发体系可以在一定程度上使聚合物分子量分布变窄。     

对氯甲基苯乙烯与丙烯腈、甲基丙烯酸酯类的自由基共聚研究

<正> 对氯甲基苯乙烯(p-CMS)是合成功能高分子的一个非常有用的起始单体,利用它的均聚以及与其它烯类单体的共聚反应,可制得含活性基团的高分子材料。但以往对该单体的聚合及共聚研究,较多的是以邻、间、对位氯甲基取代苯乙烯的混合物作为研究对象。本文采用纯对氯甲基苯乙烯,在开展对其基本性质、均聚反应机理研究的同     

表面接枝分子印迹聚合物微球的合成及评价

将聚苯乙烯-二乙烯苯微球表面功能基化, 引入引发转移终止剂(initiator-transfer-terminator agent, iniferter), 以活性自由基聚合方式研究了球形树脂表面合成印迹聚合物的方法. 在紫外光引发下, 以左旋麻黄碱为印迹分子, 甲基丙烯酸为功能单体, 在接枝Iniferter后的微球表面进行分子印迹聚合物接枝实验, 并使用不同的反应条件, 探讨了表面接枝印迹层微球制备条件对于识别能力的影响. 平衡吸附的结果表明, 表面接枝聚苯乙烯-二乙烯苯微球对于印迹分子具有亲和能力及选择性, 其识别能力来自于印迹得到的识别位点.     

BDC作为Iniferter引发苯乙烯聚合的研究

本文研究了由BDC(N,N-二乙基二硫代氨基甲酸苄酯)作为Iniferter(引发-转移-终止剂)引发苯乙烯的光聚合反应。发现转化率和分子量均随时间逐步增大,反应生成带有起始功能端基的聚合物。从顺磁谱可见BDC在光照射下分解生成的小分子自由基[·SSCN-(C_2H_5)_2]及较活泼的苄基自由基引发苯乙烯聚合产生的大分子增长自由基。探讨了这种活性自由基聚合反应机理。     

不同结构形态二氧化硅/高分子复合微凝胶材料制备研究

敏感性二氧化硅/高分子微凝胶复合材料既具有二氧化硅良好的化学稳定性、低毒性和易于功能性,又具有敏感性高分子微凝胶对外界环境(如温度、pH等)的刺激响应特性,因而广泛应用于药物控释、吸附分离、载体和微反应器等重要领域。本文根据二氧化硅和敏感性高分子复合结构的不同,对二氧化硅/高分子核-壳型复合微凝胶、高分子/二氧化硅核-壳型复合微凝胶及杂化网络结构二氧化硅-高分子复合微凝胶等三类复合材料的制备研究进展进行较为详尽地阐述和分析。     

高分子微凝胶控制合成无机-有机复合材料研究进展

高分子微凝胶是一类具有三维网络结构的分子内交联的高分子球形微粒,其物理、化学性质与其构象变化有着密切的关系,对于外界环境条件如温度、pH、离子强度、电场或磁场等的改变,微凝胶即表现出相应的体积相转变特性.近年来,基于高分子微凝胶对外界的刺激相应性与无机纳米粒子的特殊性能制备得到了各种有机-无机复合材料.本文根据微凝胶在无机微、纳米材料制备过程中所起的作用,将基于高分子微凝胶制备无机-有机复合微、纳米材料的方法分为原位合成法、物理诱捕法和聚合法,并分别从各类方法的特点和应用等方面进行详尽地分析和阐述.     

含邻苯二酚基团微凝胶的合成及其硝酸根离子响应特性

刺激响应微凝胶有望用于捕获水体中硝酸根离子,并允许材料自身的再生循环使用,但如何实现高效捕获水体中硝酸根离子颇具挑战性.本工作合成了单体2,3-二羟基-N-(2-甲基烯丙基)苯甲酰胺,并将其与苯乙烯、4-氯甲基苯乙烯、二乙烯基苯共聚,制得含邻苯二酚基团微凝胶.随着硝酸根离子浓度(以氮计)在0～40.0 mg/L范围内逐渐增大,浊度法表征表明在常温22℃下微凝胶水溶液消光度呈现持续增大趋势,而动态光散射法表征表明微凝胶粒径减小,即发生收缩.色谱法表征表明,微凝胶对硝酸根离子具有较好吸附性能,最大吸附容量达54.2 mg/g,即使对低浓度硝酸根离子(≤10 mg/L)也可在10 min内达到吸附平衡,有望用于废水处理.     

二步法合成凝胶星型聚合物

用含悬吊双键的微胶核为偶联剂,合成了不同支化度的苯乙烯-异戊二烯凝胶星型聚合物。紫外光谱测试发现二乙烯基苯可控制双键含量,链转移剂对微胶核的分子量影响较大。GPC跟踪偶联反应表明,偶联反应是快步骤,偶联度的增加是慢过程。要提高聚合物的支化度,必须考虑到空间位阻效应和双键包埋的影响。     

温敏性P(St-NIPAM)/PNIPAM-Ag复合微凝胶制备及性能研究

通过无皂乳液聚合和种子乳液聚合两步法合成苯乙烯与N-异丙基丙烯酰胺共聚物/聚N-异丙基丙烯酰胺[P(St-NIPAM)/PNIPAM]核-壳结构复合微凝胶, 再以其为模板在硝酸银水溶液中充分溶胀, 并以乙醇为还原剂, 在NH₃气氛条件下还原, 制备得到高分子微凝胶负载纳米银P(St-NIPAM)/PNIPAM-Ag的复合微凝胶材料. 通过扫描电子显微镜(SEM)、透射电子显微镜(TEM)、傅里叶变换红外光谱仪(FT-IR)、X射线衍射仪(XRD)、热分析(TGA)、紫外-可见分光光度计(UV-vis)、激光粒度分析等手段对复合微凝胶进行结构、组成和性质表征. 研究结果表明, 复合纳米银后的P(St-NIPAM)/PNIPAM-Ag复合微凝胶仍具有温敏性, 且其温度敏感性随壳层中复合纳米银含量的增加而减弱. P(St-NIPAM)/PNIPAM-Ag复合微凝胶对对硝基苯酚的还原反应具有良好的催化活性, 在45 min内基本将对硝基苯酚催化还原为对氨基苯酚.     

微凝胶胶体晶体研究进展

Poly(N-isopropylacrylamide)(PNIPAM)微凝胶粒子是一种软的胶体粒子.和单分散的SiO_2、PS、PMMA等硬的胶体粒子一样,单分散的PNIPAM微凝胶粒子也可以自组装成为高度有序的胶体晶体.微凝胶粒子软物质的特性及其对外部刺激的响应性赋予其不同于硬球的组装行为.微凝胶胶体晶体的高度有序结构及其刺激响应性使其在诸多领域有重要用途.本文分别介绍了三维及二维微凝胶胶体晶体组装的研究进展,并对已开发的基于微凝胶胶体晶体的应用进行了总结.     

Morphology evolution of polystyrene-core/poly(N-isopropylacrylamide)-shell microgel synthesized by one-pot polymerization

One-pot polymerization with macroinitiator is supposed to be a robust, facile way to synthesize well-defined coreshell nanoparticles with fixed shell thickness. To testify this, we investigated the temperature-depending morphology evolution of polystyrene(PS) core/poly(N-isopropylacrylamide)(PNIPAM) shell microgel synthesized by one-pot polymerization with PNIPAM-RAFT as macroinitiator in dimethylformamide(DMF) by transmission electron microscopy(TEM), dynamic/static light scattering(DLS/SLS) and small angle neutron scattering(SANS). It is revealed that the microgel has a core-shell structure, i.e., the core is made of pure PS, but the shell is composed of both PNIPAM-RAFT macroinitiator and crosslinked PS. In fact, there are 92.0 wt% D2 O, 6.7 wt% PNIPAM and 1.3 wt% PS in the shell in its aqueous dispersion at 21 °C; therefore, its shell thickness is much larger than the extended chain length of the macroinitiator as revealed by both SANS and DLS observations. Competitive growth of styrene, divinylbenzene and PNIPAM macroinitiator as well as possible chain transfer from amine proton of PNIPAM side chain may lead to the larger shell thickness, compared with the extended chain length of the macroinitiator. Our work can shed light on the real morphology control in one-pot polymerization.     

Diffusion energies of oxygen diffusing into polystyrene (PS)/poly (N‐isopropylacrylamide) composites

Diffusion coefficient of oxygen penetrating into polystyrene (PS) latex/poly (N‐isopropylacrylamide) (PNIPAM) microgel composite films were measured using Fluorescence technique. Three different (5, 15, and 40 wt%) PS content films were prepared from PS/PNIPAM mixtures. Diffusivity of PS/PNIPAM composite films were studied by diffusion measurements which were performed over the temperature range of 24–70°C. Pyrene was used as the fluorescent probe. The diffusion coefficients (D) of oxygen were determined using the Stern–Volmer fluorescence quenching method combined with Fickian transport and were computed as a function of temperature for each PS content film. The results showed that D values were strongly dependent on both temperature and PS content in the film. Diffusion energies were measured and found to be dependent on the composition of the composite films. Copyright © 2011 John Wiley & Sons, Ltd.     

嵌段共聚物微胶束行为的研究Ⅲ．动态激光光散射法研究聚（苯乙烯－异戊二烯）星形嵌段共聚物在选择性溶剂中微胶束的形成过程

采用动态激光光散射研究聚（苯乙烯－异成二烯）（ＰＳ—ＰＩ）星形嵌段共聚物在选择性溶剂二氧六环／甲醇混合体系中微胶束的形成过程。讨论了温度、混合溶剂的组成、星形嵌段共聚物的臂数及组成对微胶束形成的影响。验证了临界接触浓度的存在。并就不同结构的星形嵌段共聚物形成微胶束的形成进行了讨论。     

Electric Conductance of Films Prepared from Polymeric Composite Nanoparticles

Summary : Novel polymeric particles of spherical shape consisting of an electrically insulating poly(styrene-co-acetoacetoxyethyl methacrylate) (PS/PAAEM) core and a conductive shell of poly(3,4-ethylenedioxythiophene) (PEDOT) were synthesized. Electric measurements showed a strong dependence of the conductivity on weight ratio of PEDOT to PS/PAAEM in the composite. As the PEDOT content varied from 2 to 31.4 wt.-%, resistivity of the resulting material changed exponentially from 12 GΩ cm to 100 Ω cm, depending also on the type of the used oxidation agent. Similar studies were performed on the basis of insulating poly(N-vinylcaprolactam-co-acetoacetoxyethyl methacrylate) (PVCL/PAAEM) microgel particles, which acted as microreactors for the synthesis of conductive PEDOT nanorods. In microgel systems, the conductivity was lower than in core-shell systems, when the PEDOT content was less than 5 wt.-%. Above this value of PEDOT concentration, the conductivities in the two systems became similar.     

Functionalized Star‐Like Polystyrenes as Organic Supports of a Tridentate Bis(imino)pyridinyliron/Aluminic Derivative Catalytic System for Ethylene Polymerization

Summary: Star‐like polystyrenes composed of a microgel core with arms functionalized with a few hydroxy‐ or methoxy‐ended ethylene oxide units were used as organic supports for a tridentate bis(imino)pyridinyliron catalyst towards ethylene polymerization. When used as supports of 2,6‐bis[1‐2,6(diisopropylphenyl)imino]ethylpyridynyl iron dichloride in the presence of various alkylaluminium compounds, the supported catalysts enabled the production, with a high catalytic activity, of polyethylene beads of a spherical morphology and high bulk density. A good control of the polyethylene molar mass distribution could also be achieved, which was explained by a lowering of the transfer reaction to the aluminium derivative, as compared to homogeneous conditions.

SEM image of PE particles prepared in the presence of trimethylaluminium supported on a PS microgel with an iron catalyst (TMA/Fe = 800).     

PAM-PAA microgel inverse opal photonic crystal and pH response

The colloidal crystal template or opal with a closed-packed face-centered cubic (fcc) lattice was prepared from monodisperse polystyrene (PS) spheres by vertical sedimentation.The template provided void space for infiltration of monomer precursor composed of acrylate acid,acrylamide and ammonium persulfate,as well as microgel from the subsequent copolymerization.The sample was immersed in dimethylbenzene for completely removing PS spheres to form PAM inverse opal hydrogels (IOH_(PAM)) or PAM/PAA inverse opal hydrogels (IOH_(PAM/PAA)) photonic crystals.The PS spheres were replaced by air spheres,which interconnected each other through the windows.The study of responses to pH show that there are two peaks for both IOH_(PAM) and IOH_(PAM/PAA) films,but the IOH(PAM/PAA) peaks shift to higher pH,and the peaks are independent with the AA content. (?)2007 Xiao Dong Wang.Published by Elsevier B.V.on behalf of Chinese Chemical Society.All rights reserved.     

Facile synthesis of hollow polymeric microparticles possessing various morphologies via seeded polymerization

In this paper, hollow poly(styrene-co-divinylbenzene-co-methacrylic acid) microparticles possessing various morphologies were synthesized by a combination of seeded polymerization and SPG membrane emulsification. Three families of polystyrene (PS) microspheres with various molecular weights but similar diameters were fabricated by SPG membrane emulsification. These PS microspheres were used as seeds to investigate the effect of their molecular weight on the phase separation between the PS seeds and microgel-like networks formed during seeded polymerization and on the morphologies of the resultant particles. Our study revealed that three resultant microparticles possessed diameters of ca. 10?μm and hollow cavities. The shell thickness of the particles became thinner as M _w increased from 3.5?×?10⁴ to 28.0?×?10⁴. The morphological evolution of the microparticles during seeded polymerization was monitored, and these results verified the influence of the molecular weight of the PS seeds on the phase separation behavior and hence the morphologies of the resultant particles.     

含铅聚合物微凝胶与硫化氢反应前后在良溶剂中的分子扩散行为

用溶液聚合法制备出轻度交联的含铅微凝胶,用光子相关光谱技术测定其在良溶剂中与H2S反应前、后的扩散行为,由外推法得到在浓度无限稀时的分子扩散系数,给出微凝胶的流体力学半径。结果表明:相同量的含铅微凝胶在不同的初始浓度下与H2S反应,生成含PbS纳米微粒的凝胶；但其体积增大不同,这说明H2S与含铅微凝胶的反应既可以在分子内也可以在分子间进行,分子间的反应使含硫化铅微凝胶扩散系数随浓度的变化曲线的线性范围变小。     

含铅聚合物微凝胶与硫化氢反应前后在良溶剂中的分子扩散行为

用溶液聚合法制备出轻度交联的含铅微凝胶,用光子相关光谱技术测定其在良溶剂中与H₂S反应前、后的扩散行为,由外推法得到在浓度无限稀时的分子扩散系数,给出微凝胶的流体力学半径。结果表明:相同量的含铅微凝胶在不同的初始浓度下与H₂S反应,生成含PbS纳米微粒的凝胶;但其体积增大不同,这说明H₂S与含铅微凝胶的反应既可以在分子内也可以在分子间进行,分子间的反应使含硫化铅微凝胶扩散系数随浓度的变化曲线的线性范围变小。