芳叔胺-氯化苄引发聚合动力学的研究

由N,N-二甲基苯胺(DMA)-氯化苄(BzCl)两者构成的混合物或其季铵盐,皆可引发乙烯型单体自由基聚合反应,并已应用于某些纤维的接枝共聚改性工作.本文为了进一步探讨DMA-BzCl体系的引发特性,采用膨胀仪法(高真空装置下聚合),以苯为溶剂,于60℃测定了该体系引发甲基丙烯酸甲酯(MMA)聚合的反应速率.求得聚合速率Rp∝[MMA],Rp∞[Ⅰ](当[DMA]=[BzCl]=[Ⅰ]时),Rp∞[BzCl]~1/2.(当[DMA]不变时),并推导得如下动力学方程式,R_p=-d[M]/dt=Kp(K_l/K_t)~(1/2)[DMA]~(1/2)[BzCl]~(1/2)[DMA].还研究了DMA苯环上取代基的效应.若为吸电子取代基时,使聚合速率降低,降低的程度符合于Hammett方程.     

乳化剂浓度对苯乙烯乳液聚合成核机理的影响

以苯乙烯（St）为单体、十二烷基硫酸钠（SDS）为乳化剂、过硫酸钾（KPS）为引发剂,重点研究了该乳液聚合体系中乳化剂浓度（[S]）对胶束成核和沉淀成核的影响规律。结果表明,当SDS浓度高于CMC时（[S]≥ 8mmol/L）,体系的成核以胶束成核为主;当[S]=2mmol/L时,体系的成核以沉淀成核为主;当2mmol/L<[S]< 8mmol/L时,体系同时以沉淀成核和胶束成核两种方式成核,且胶束成核所占的比例随着SDS浓度的增加而增大。研究了聚合反应过程中SDS浓度对单位体积水中乳胶粒个数（Np）的影响规律：当[S]≥8mmol/L时,Np∝[S]0.9;当[S]<8mmol/L时,Np∝[S]0.8。     

丙烯酰胺与甲基丙烯酰氧乙基三甲基氯化铵反相乳液聚合动力学

以丙烯酰胺(AM)和甲基丙烯酰氧乙基三甲基氯化铵(DMC)为单体,失水山梨糖醇脂肪酸酯(Span 80)和失水山梨醇单油酸酯聚氧乙烯醚(Tween 80)为乳化剂,液体石蜡为油相,2,2′-偶氮二异丙基咪唑啉二盐酸盐(VA-044)为引发剂,研究AM与DMC反相乳液聚合动力学,反相乳液聚合速率方程为Rp=k[M]2.12[I]0.55[E]0.65,AM与DMC反相乳液聚合表观活化能为80.65 k J·mol-1。通过反相乳液聚合速率随时间的变化关系得出其成核机理倾向于单体液滴成核。用Fireman-Ross法研究了共聚单体竞聚率,分别为r AM=0.23、r DMC=1.93,AM与DMC在聚合物链上发生无规共聚反应。单体量增大、引发剂量减少、乳化剂量增大、聚合温度降低均使共聚产物的特性黏数增大。     

负载钛催化1-丁烯本体聚合动力学

采用TiCl4/MgCl2-Al(i-Bu)3催化体系在10 L聚合釜中研究了本体法1-丁烯的聚合动力学.结果表明,在反应温度为20 ℃的条件下,聚合的速率方程为Rp=157[Ti]1.1[Bt]PH20.4;在10～30 ℃时的聚合活化能为46 kJ/mol.提高催化剂浓度、聚合温度和氢气压力均能明显提高单体转化率,加快聚合速率.     

反应性乳化剂参与的多元乳液共聚合动力学研究

以烯丙基烷基酚聚氧乙烯醚硫酸盐(HS-10)为乳化剂,丙烯酸丁酯、丙烯酸、甲基丙烯酸β-羟乙酯、醋酸乙烯酯为单体进行乳液共聚合,研究乳化剂浓度、单体浓度对聚合速率(Rp)影响。实验结果表明,乳液聚合速率随反应性乳化剂和单体浓度增加而增加,聚合速率方程为Rp∝[HS-10]0.174[AA]0.395[BA]0.393[HEM A]0.271[VA c]1.460。     

苯乙烯／甲基丙烯酸β羟乙酯乳液共聚合研究

采用十二烷基硫酸钠为乳化剂,将甲基丙烯酸羟乙酯／苯乙烯进行乳液共聚。研究了单体配比、引发剂浓度、单体浓度、乳化剂浓度、反应温度等因素对聚合速率（Rp）的影响。结果表明,聚合速率随着引发剂浓度、乳化剂浓度、单体浓度、反应温度的增加而增加．随着单体HEMA配比的增加而增加。该体系的表观活化自由能为73．36kJ／mol,Rp=K[M]^1.24[I]^0.61[E]^0.24。     

St/MMA/(mono-BM)三元无皂乳液共聚动力学

在PVA助溶稳定剂的作用下,通过间歇法无皂种子乳液聚合制备了St/MMA/(mono-BM)三元共聚物。研究了单体总浓度[M],引发剂浓度[I],PVA浓度[P],聚合温度对St/MAA/(mono-BM)无皂种子乳液聚合动力学的影响。实验表明:Rp∝[M]2.38,-M w∝[M]0.62;Rp∝[I]0.883,-M w∝[I]-0.71。采用粒度测定仪,凝胶色谱和示差扫描量热法表征了共聚物乳液。粒度分析显示乳液总平均粒径为55 nm;DSC谱图显示三元共聚物只有单个Tg,聚合体系不存在微相分离区;GPC谱表明共聚物分子质量分布仅为1.28,接近单分散体系。     

以含氟预聚物为助稳定剂的苯乙烯细乳液聚合

以苯乙烯(St)和甲基丙烯酸十二氟庚酯(G04)的无规共聚物(PSF)作为助稳定剂,进行St的细乳液聚合,考察了不同含氟量的PSF对转化率、聚合速率R_p、液滴粒径和成核粒子数的影响。结果表明,当含氟量由0增加到34.9%,转化率由67.5%增加到80.1%,R_p由0.75×10^-2 mol · L^-1·min^-1提高到1.74×10^-2 mol ·L^-1·min^-1;PSF的含氟量对细乳化后液滴粒径的影响较小,但对聚合过程中成核粒子数有较大影响。当含氟量由0增加到34.9%时,反应3 h后,体系成核粒子数由每升1.83×10^16个增加到2.07×10¹⁶个,并初步分析了PSF可以单独作为助稳定剂的作用机理。     

二茂铁桥联聚倍半硅氧烷修饰电极测定抗坏血酸

以1,1′-双[2-（三乙氧基硅基）乙基]二茂铁单体及正硅酸乙酯为前驱物,经溶胶-凝胶过程制备了二茂铁功能化的聚倍半硅氧烷修饰电极,并将该修饰电极用于抗坏血酸（H2A）的电催化氧化测定。在pH=8．0的0．1mol·L-1 NaClO4-H3PO4缓冲溶液中,氧化峰峰电流和H2A浓度呈良好线性关系,动态线性范围2．0×10-5～1．0×10-3mol·L-1,相关系数为0．904,检测限为1．3×10-5mol·L-1。     

痕量水对α-蒎烯聚合反应调控研究

以α-蒎烯为原料,采用AlCl3/SbCl3为催化体系,探讨了痕量水对聚合反应的影响.结果显示,在一定的工艺条件下,溶剂的含水量对反应起主要作用,当溶剂含水量为0.56×10-2～2.22×10-2 mol·L-1、α-蒎烯含水量<2.78×10-2 mol·L-1时,有利于获得高软化点、高得率的萜烯树脂.     

Chemospecific ring-opening polymerization of α-methylenemacrolides

α-Methylenemacrolides having various groups, such as aromatic, ether, and amine, were enzymatically, anionically, and radically polymerized. The polymerization with the lipase catalyst successfully afforded polymers only through the ring-opening process, whereas the vinyl polymerizations selectively proceeded by using anionic and radical initiators. The polyesters obtained by the enzymatic polymerization have a polymerizable methacrylic methylene group in the main-chain, in addition to the aromatic and polar groups, and were further radically polymerized to quantitatively produce a cross-linked polymer gel.     

Accelerated pressure synthesis and characterization of 2-oxazoline block copolymers

The cationic ring-opening polymerization of 2-oxazolines in acetonitrile was investigated under pressure conditions utilizing methyl tosylate as initiator of which the single crystal X-ray structure is described as well. The polymerization kinetics were studied and compared with previously reported microwave-assisted pressure polymerizations. Moreover, a series of block copolymers was synthesized in an automated parallel synthesis robot utilizing this pressure polymerization method. The resulting block copolymers were characterized with both differential scanning calorimetry and contact angle measurements to determine the effect of copolymer composition on glass transition temperature, melting point and surface energy. Atomic force microscopy was applied to further investigate the possible phase separation.     

苯乙烯的间歇-半连续RAFT细乳液聚合

进行了苯乙烯的间歇-半连续RAFT细乳液聚合,考察了半连续段的起点、单体滴加速率及最终胶乳固含量的影响。结果发现：从最终胶乳的稳定性考虑,半连续聚合的起点选择在间歇聚合的高转化率时期更好;若综合考虑胶乳的稳定性、分子量及其分布、固含量、乳化剂及共稳定剂在胶乳中的残留率等因素,半连续聚合的起点可适当提前,但必须在间歇聚合成核期结束后。过早容易引起乳液的失稳;过迟会延长反应时间,降低聚合物的制备效率,导致死聚物链含量升高。聚合体系的稳定性与胶乳的固含量密切相关,最终固含量不宜超过40％。采用间歇-半连续二段聚合工艺可以制得窄分子量分布(PDI＝～1.3),低乳化剂及共稳定剂残留量（～1.5%,质量）的高分子量聚合物(≈8×10⁴g&#8226;mol^-1)。     

Particle formation mechanism in radical polymerization in miniemulsion based on in situ surfactant formation without high energy homogenization

Conventional radical polymerization of styrene at 70 °C in aqueous miniemulsion generated using the in situ surfactant technique, without use of high energy mixing, has been investigated in detail. The surfactant potassium oleate was formed in situ by reaction between oleic acid and potassium hydroxide at the styrene/water interface. The particle formation mechanism was investigated by use of pyrene as a probe, revealing that under suitable conditions with an oil-phase initiator, particle formation occurs primarily via monomer droplet nucleation. The droplet/particle stability is however inferior to that in a typical miniemulsion generated employing ultrasonication, as manifested by a marked increase in droplet/particle size with conversion and a bimodal droplet/particle size distribution by weight. The droplet/particle stability increases with increasing amount of oleic acid, hexadecane, water, and the ratio potassium hydroxide:oleic acid, respectively.     

Synthesis of latex particles by ring-opening metathesis polymerization

This paper reviews the recent discoveries that were achieved by our group in the field of particle synthesis via ring-opening metathesis polymerization (ROMP). Both polynorbornene and polybutadiene-based particles were prepared by the respective ROMP of norbornene and cyclooctadiene initiated by (PCy₃)₂Cl₂RuCHPh using several methods of polymerization in dispersed media, such as dispersion, suspension and miniemulsion. Depending upon the process implemented, particles size was found to range from 300 nm to 20 μm.     

微乳液聚合研究新进展

对微乳液聚合的特点、聚合机理及动力学影响因素进行了总结和评述，指出了今后微乳液聚合研究的几个关键问题。     

等离子体引发丙烯酸(2-乙基)已酯乳液聚合

采用等离子体引发聚合的方法 ,进行了丙烯酸 ( 2 -乙基 )已酯 (简称 EHA)的乳液聚合。考察了后聚合时间、放电功率、乳化剂浓度对聚合转化率及特性粘数的影响。并对丙烯酸酯等离子体引发本体、乳液聚合进行了比较     

Microwave-Assisted RAFT Polymerization

Advances in controlled radical polymerization (CRP) have facilitated access to well-defined polymers with controlled molecular weight, topology, and functionality. However, despite the benefits afforded by many CRP techniques, control over these key polymer attributes often comes at the expense of polymerization rate. One method proposed for accelerating chemical synthesis is microwave heating. This review highlights recent examples of microwave heating being applied during reversible addition-fragmentation chain transfer (RAFT) polymerization. In addition to successfully leading to homopolymers from a variety of monomers, block copolymers have also been prepared by microwave-assisted RAFT, which suggests that the high polymerization rates observed do not necessarily lead to significant end group loss from termination. Despite significant debate regarding the origin of rate enhancement observed during microwave-assisted reactions, the reports included herein provide insight into mechanisms by which well-defined functional polymers can be prepared in an accelerated fashion.     

超声引发聚合反应的研究

综述了超声波在一些聚合方法中的应用。     

水性含硅聚合物涂料的制备与应用

乳液聚合法是制备水性含硅聚合物最常见、最有效的方法。介绍了种子乳液聚合、核/壳乳液聚合、无皂乳液聚合、微乳液聚合、互穿网络聚合等制备水性含硅聚合物的方法,并对水性含硅聚合物涂料的应用做了探讨。