含氢聚甲基硅氧烷/丙烯酸丁酯/羟甲基丙烯酰胺复合乳液的制备方法对乳液性质的影响

采用自由基引发剂用３种不同的聚合方法制备了新型的含氢聚甲基硅氧烷（ＰＨＭＳ）／丙烯酸丁酯（ＢＡ）／羟甲基丙烯酰胺（ＮＭＡ）复合聚合物乳液。详细讨论了不同聚合方法对乳液稳定性和乳胶粒子的影响，同时对聚合反应的机理、产物的结构作了考察．结果表明：通过乳液聚合，得到了ＰＨＭＳ／ＢＡ／ＮＭＡ共聚物；单体乳液滴加法所得乳液粒径较小，乳液性能稳定，是制备ＰＨＭＳ／ＢＡ／ＮＭＡ复合聚合物乳液较适宜的方法．     

三元无皂乳液共聚合动力学及其模型的研究

以苯乙烯（ Ｓｔ） 和甲基丙烯酸甲酯（ Ｍ Ｍ Ａ） 为主单体,以丙烯酸（ Ａ Ａ） 为功能单体进行了无皂乳液批量共聚合．考察了功能单体浓度、引发剂过硫酸铵（ Ａ Ｐ Ｓ） 浓度及聚合温度对其动力学行为的影响．建立了转化率 时间关系曲线的模型函数——— Ｇａｍ ｍａ 积分函数,用它拟合了转化率 时间关系曲线,获得了聚合过程的重要特征参数,如平均成核速率（ Ｎ Ｖ） ,聚合最大速率（ Ｍ Ｖ） 和平稳期平均聚合速率（ Ａ Ｖ） 及成核结束和聚合进入完成期对应的转化率．同时对聚合速率与以上各聚合参数的关系数据进行了非线性拟合,得到了它们之间的关系式．研究发现拟合误差很小,成核结束时转化率在１５ ％ 以内,成核及聚合速率均随以上参数增大而增大,引发剂过硫酸铵在聚合过程中起决定作用．     

2-(N,N-二乙基二硫代氨基甲酰氧基)乙酸苄酯存在下苯乙烯光聚合

研究了２ Ｎ, Ｎ 二乙基二硫代氨基甲酰氧基乙酸苄酯（ Ｂｚ Ｄ Ｃ Ａ） 引发的苯乙烯光聚合反应,发现单体转化率和数均分子量（ Ｍｎ） 都随反应时间而增加,在反应时间相同时随着 Ｂｚ Ｄ Ｃ Ａ 浓度的增加单体转化率升高而 Ｍｎ 降低．聚苯乙烯（ Ｐ Ｓ） 的 Ｍｎ 同单体转化率成线性关系并同理论计算值符合得较好．以２ 甲基 ２ 亚硝基丙烷（ Ｍ Ｎ Ｐ） 为捕捉剂用（ Ｅ Ｐ Ｒ） 技术对聚合反应机理进行了研究．认为 Ｂｚ Ｄ Ｃ Ａ 引发的 Ｓｔ 光聚合是一个“活性”聚合过程     

含氢聚甲基硅氧烷／丙烯酸丁酯／羟甲基丙烯酰胺复合乳液的制备方法对 …

采用自由基引发剂用３种不同的聚合方法制备了新型的含氢聚甲基硅氧烷（ＰＨＭＳ）／丙烯酸丁酯（ＢＡ）／羟甲基丙烯酰胺（ＮＭＡ）复合聚合物乳液，详细他不同聚合方法对乳液稳定性和乳胶粒子的影响。同时对聚合反应的机理，产物的结构作了考察，结果表明：通过乳液聚合，得到了ＰＨＭＳ／ＢＡ／ＮＭＡ共聚物，单体乳液滴加法所得乳液粒径较小，乳液性能稳定，是制备ＰＨＭＳ／ＢＡ／ＮＭＲ复合聚合物乳淤较适宜的方法。     

原子转移自由基聚合合成(甲基)丙烯酸酯类模型聚合物及其动力学研究

本文采用一种新颖的活性自由基聚合—原子转移自由基聚合（ＡＴＲＰ）的方法，以１－溴代苯乙烷作为引发剂，过渡金属卤化物与配位剂络合物（ＣｕＢｒ／２，２’－联吡啶）为催化体系，环己酮为溶剂，进行了甲基丙烯酸正丁酯（ＢＭＡ）和丙烯酸正丁酯（ＢＡ）的活性聚合。得到具有指定分子量和窄分子量分布（１．２＜Ｍｗ／Ｍｎ＜１．５）的模型聚合物。计算并讨论了两聚合体系的ＡＴＲＰ的动力学数据     

SOCl2／SnCl4—DMSO／n—Bu4NCl引发体系苯乙烯活性阳离子聚合反应的研究

研究表明，ＳＯＣｌ２／ＳｎＣｌ４引发体系的苯乙烯聚合反应很快，但所得聚合产物的分子量分布宽（Ｍｗ／Ｍｎ＝４．３７），且其ＧＰＣ曲线呈多重峰；单独加入季铵盐（ｎ－Ｂｕ４ＮＣｌ）或二甲基亚砜（ＤＭＳＯ）可使聚合产物分子量分布明显变窄，并随浓度的增加而加强，但程度有限，不显示活性聚合特征；ＤＭＳＯ和ｎ－Ｂｕ４ＮＣｌ同时加入，表现出协同效应，不仅能保持较高的聚合反应活性，而且产物分子量分布很窄（Ｍｗ／Ｍｎ＝１．２７），分子量随单体转化率增加而增加，且线性关系良好，聚合物链数只与引发剂初始浓度相关，显示活性聚合特征。     

α-溴代丁酸乙酯/CuBr/联吡啶体系引发的活性自由基聚合反应

用α 溴代丁酸乙酯为引发剂，ＣｕＢｒ和２，２’ 联吡啶（ＢＰＹ）为催化剂，研究了ＭＭＡ、Ｓｔ、ＭＡ在８０℃下，ＭＭＡ在室温下（２０℃）的自由基活性聚合机理．通过转化率与数均分子量，理论分子量和实测分子量的关系，以及分子量分布，证明这些体系均具有活性聚合的特征．计算了三种聚合体系的动力学数据．讨论了温度、单体结构对聚合体系自由基活性特征的影响．     

丙烯酸甲酯与醋酸乙烯酯的种子乳液聚合

以过硫酸铵（ＡＰＳ） 为引发剂,合成了粒径分布较均匀的聚醋酸乙烯酯种子乳液（ＰＶＡｃ） ,然后以丙烯酸甲酯（ ＭＡ） 为第二单体和以油溶性偶氮二异丁腈（ＡＩＢＡ） 为引发剂,分别进行不溶胀与溶胀条件下的无皂种子乳液聚合,并用透射电子显微镜（ＴＥＭ） 表征了胶粒形态．表明在不溶胀条件下,胶粒形态随ＰＶＡｃ／ ＭＡ 重量比的不同而变化,当ＰＶＡｃ／ ＭＡ 为１／２ 时,形成以ＰＭＡ 为核,ＰＶＡｃ 为壳的胶粒．在溶胀条件下则得到类似互穿网络型乳胶粒．     

奋乃静和有机过氧化物引发体系及含奋乃静的缓释药膜

研究了含叔胺基结构的药物奋乃静（Ｐｅｒｐｈｅｍｎａｚｉｎｕｍ，简称ＰＥＲＰ）和有机过氧化物所构成的引发体系，并以此体系引发丙烯酸酯类单体聚合所得的含奋乃静缓释药膜的缓释行为．结果表明，奋乃静（ＰＥＲＰ）和过氧化苯甲酰（ＢＰＯ）引发体系引发甲基丙烯酸甲酯（ＭＭＡ）聚合的动力学方程为：Ｒｐ＝Ｋｐ［ＢＰＯ］０５［ＰＥＲＰ］０５［ＭＭＡ］１０，聚合表观活化能Ｅａ＝４１８ＫＪ／ｍｏｌ，从而确定此引发体系的引发机理为氧化还原引发机理．ＰＥＲＰ ＢＰＯ体系能在４０℃温度下，引发丙烯酸酯类单体共聚，而能形成含有奋乃静的缓释药膜     

胶束体系中光敏聚合的研究 Ⅶ．微泡水溶液体系中光聚合的研究

研究了在双十六烷基二甲基溴化铵（ＤＣＤＡＢ）形成的微泡溶液中，二苯酮（ＢＰ）／三乙胺（ＴＥＡ）体系的光化学初级反应和引发ＭＭＡ光聚合反应．动力学实验结果表明，ＤＣＤＡＢ微泡对聚合反应有显著的催化作用，使聚合速度提高近４倍左右，其效果和离子型胶束的催化作用结果相近．由ＤＣＤＡＢ微泡中光聚合得到的产物ＰＭＭＡ，具有较高的结构规整性，它的间同和全同结构可达７０％左右．     

Polymerization of butyl acrylate in anionic microemulsion

Butyl acrylate was initiated with KPS or BPO to polymerize at high monomer concentration in the microemulsions with SBOA (sodium 12-butinoyloxy-9-octadecenate) as emulsifier. The microemulsion remained clear or reddish. It was found that the constant polymerization period appeared in most microemulsions and the length of it varied with the concentration of monomer and the initiating rate. When microemulsions were initiated with KPS, the overall polymerization rate increased with the emulsifier concentration; while initiator was BPO, it showed the inverse tendency. It was attributed to the difference between the initiating mechanism of the two initiators. © 1996 John Wiley & Sons, Inc.     

Micellar nucleation differential microemulsion polymerization

Polymer nanoparticles within the range of 2–5 nm with a solid content of more than 13 wt.% and a narrow molecular weight polydispersity (Mw/Mn ∼ 1.1) were for the first time prepared using a micellar nucleation differential microemulsion polymerization system emulsified by sodium dodecyl sulfate (SDS), with SDS/monomer (methyl methacrylate) and SDS/H₂O weight ratios of up to 1:16 and 1:100, respectively. It was found that for benzoyl peroxide (BPO), micellar nucleation is more favorable for the synthesis of smaller polymer nanoparticles than ammonium persulfate (APS) which gives rise to homogeneous nucleation and 2,2′-azobisisobutyronitrile (AIBN) which involves partially heterogeneous nucleation. In the polymerization process, there exists a critical stability concentration (CSC) of SDS, above which the size of the nanoparticles is to be minimized and stabilized. With an increase in the monomer addition rate, the polymerization system changes from a microemulsion system to an emulsion system. A mechanism was proposed to describe the micellar nucleation process of differential microemulsion polymerization. This study may contribute to the development of fine polymer nanoparticles for drug delivery systems.     

水溶性和油溶性引发剂引发γ-甲基丙烯酰氧基丙基三甲氧基硅烷/苯乙烯细乳液共聚合的比较

分别用水溶性的过硫酸钾(KPS)和油溶性的2,2′-偶氮二异丁腈(AIBN)为引发剂引发γ-甲基丙烯酰氧基丙基三甲氧基硅烷(MPS)/苯乙烯(St)细乳液共聚合反应.比较了两类引发剂对MPS/St共聚合动力学(包括硅氧烷水解动力学和MPS/St的自由基共聚合动力学)、乳胶粒稳定性和共聚产物微结构的影响.     

水分散体系中由BPO或KPS引发的苯乙烯反向原子转移自由基聚合

分别以过氧化二苯甲酰 (BPO)和过硫酸钾 (KPS)为引发剂、1 ,1 0 邻二氮菲为催化剂配体、十二烷基磺酸钠为乳化剂 ,在水分散体系中进行了苯乙烯的反向原子转移自由基聚合反应 .结果表明 ,对于BPO引发的苯乙烯乳液聚合反应 ,必须由CuBr和CuBr2 形成复合催化剂体系才能达到较好的控制效果 ,其中CuBr可以是直接加入到催化剂体系中 ,也可以是由CuBr2 与Cu0 就地快速反应生成 .CuBr迅速地与BPO反应而实现活性聚合中所谓的“快引发” ,从而有效地控制苯乙烯的聚合反应 .对于KPS引发的苯乙烯乳液聚合体系 ,反应介质的pH值对聚合有很大的影响 ,反应速度随着反应介质pH值的升高而加快 .实验结果表明 ,由两种不同引发剂引发的苯乙烯的乳液的粒径及粒径分布也有很大的差异     

The reversible addition-fragmentation chain transfer （RAFT） miniemulsion polymerization of vinyl acetate mediated by xanthate

The reversible addition-fragmentation chain transfer(RAFT) miniemulsion polymerization of vinyl acetate(VAc) mediated by methyl(methoxycarbonothioyl) sulfanyl acetate(MMSA) was carried out.The results showed that polymerizations initiated by AIBN and KPS proceeded in a controlled way.The RAFT miniemulsion polymerization of VAc initiated by KPS showed the shorter inhibition period,higher propagation rate coefficient and final conversion than those in experiment initiated by AIBN.When the monomer conversio...     

甲基丙烯酸-β-羟基-γ-二烷氨基丙酯的合成及聚合

由甲基丙烯酸失水甘油酯与三烷基胺合成了甲基丙烯酸-2-羟基-3-二甲氨基丙酯(DMAHPMA)及甲基丙烯酸-2-羟基-3-二乙氨基丙酯(DEAHPMA),并进行了在各种自由基引发剂下的本体聚合。发现BPO不能使之聚合,其它过氧化物,如LPO,TBH,CHP,KPS等能引发聚合。测定了DEAHPMA在CHP,LPO,AIBN引发下的初期聚合速度Rp,并计算出它们的聚合活化能,据此,认为CHP,LPO以氧化还原机理引发DEAHPMA的聚合。 DMAHPMA在10％的盐水溶液中,不加悬浮稳定剂,即能成功地进行悬浮聚合。     

On the emulsion polymerization of styrene in the presence of a nonionic emulsifier

The batch emulsion polymerization kinetics of styrene (St) initiated by a water-soluble peroxodisulfate in the presence of a nonionic emulsifier was investigated. The polymerization rate versus the conversion curves showed two nonstationary rate intervals, two rate maxima, and Smith–Ewart Interval 2 (nondistinct). The rate of polymerization and number of nucleated polymer particles were proportional to the 1.4th and 2.4th powers, respectively, of the emulsifier concentration. Deviation from the micellar nucleation model was attributed to the low water solubility of the emulsifier, the low level of the micellar emulsifier, and the mixed modes of particle nucleation. In emulsion polymerizations with a low emulsifier concentration, the number of radicals per particle and particle size increased with increasing conversion, and the increase was more pronounced at a low conversion. By contrast, in emulsion polymerizations with a high emulsifier concentration, the number of radicals per particle decreased with increasing conversion. This is discussed in terms of the mixed models of particle nucleation, the gel effect, and the pseudobulk kinetics. The formation of monodisperse latex particles was attributed to coagulative nucleation and droplet nucleation for the polymerizations with low and high emulsifier concentrations, respectively. The effects of the continuous release of the emulsifier from nonmicellar aggregates and monomer droplets, the close-packing structure of the droplet surface, and the hydrophobic nature of the emulsifier on the emulsion polymerization of St are discussed. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 4422–4431, 1999     

Particle nucleation and monomer partitioning in styrene O/W microemulsion polymerization

Particle nucleation in the polymerization of styrene microemulsions was found to take place throughout the polymerization as indicated by measurements of the particle number as a function of conversion. A mechanism based on the nucleation in the microemulsion droplets was proposed to explain the experimental findings although homogeneous nucleation and coagulation during polymerization were not completely ruled out. A thermodynamic model was developed to simulate the partitioning of monomer in the different phases during polymerization. The model predicts that the oil cores of the microemulsion droplets were depleted early in the polymerization (4% conversion). Due to the high monomer/polymer swelling ratio of the polymer particles, most of the monomer resides in the polymer particles during polymerization. The termination of chain growth inside the polymer particles was attributed to the chain transfer reaction to monomer. The low n? (less than 0.5) of the microemulsion system was attributed to the fast exit of monomeric radicals.     

Miniemulsion polymerization of styrene with liquid polybutadiene as the sole co-stabilizer

A low-molecular-weight liquid polybutadiene (LPB) is employed as the sole co-stabilizer in miniemulsion polymerization of styrene in present work. Results indicate that the LPB can be used as an effective co-stabilizer to retard the diffusional degradation of monomer droplets in miniemulsion system and get stable miniemulsions. When the miniemulsions were initiated, particle formation occurred predominantly by monomer droplet nucleation. Moreover, the effects of various reaction parameters on the polymerization kinetics and the nucleation mechanisms were also investigated. These parameters include the level of LPB ([LPB]) and the concentrations of SDS ([SDS]) and potassium persulfate ([KPS]). It is shown that the polymerization rate indicates little dependence on [LPB], while increases with increasing [SDS] and [KPS]. Competition between droplet nucleation and homogeneous nucleation occur in the course of polymerization, but droplet nucleation becomes more important by increasing [LPB] or decreasing [SDS]. Furthermore, the result that the particle size is rather insensitive to changes in [KPS] provides the most compelling evidence for the dominant droplet nucleation.     

Microemulsion polymerization of styrene in the presence of a cationic emulsifier

The principal subject discussed in the current paper is the radical polymerization of styrene in the three- and four component microemulsions stabilized by a cationic emulsifier. Polymerization in the o/w microemulsion is a new polymerization technique which allows to prepare the polymer latexes with the very high particle interface area and narrow particle size distribution. Polymers formed are very large with a very broad molecular weight distribution. In emulsion and microemulsion polymerizations, the reaction takes place in a large number of isolated loci dispersed in the continuous aqueous phase. However, in spite of the similarities between emulsion and microemulsion polymerization, there are large differences caused by the much larger amount of emulsifier in the latter process. In the emulsion polymerization there are three rate intervals. In the microemulsion polymerization only two reaction rate intervals are commonly detected: first, the polymerization rate increases rapidly with the reaction time and then decreases steadily. Essential features of microemulsion polymerization are as follows: (1) polymerization proceeds under non-stationary state conditions; (2) size and particle concentration increases throughout the course of polymerization; (3) chain-transfer to monomer/exit of transferred monomeric radical/radical re-entry events are operative; and (4) molecular weight is independent of conversion and distribution of resulting polymer is very broad. The number of microdroplets or monomer-starved micelles at higher conversion is high and they persist throughout the reaction. The high emulsifier/water ratio ensures that the emulsifier is undissociated and can penetrate into the microdroplets. The presence of a large amount of emulsifier strongly influences the reaction kinetics and the particle nucleation. The mixed mode particle nucleation is assumed to govern the polymerization process. At low emulsifier concentration the micellar nucleation is dominant while at a high emulsifier concentration the interaction-like homogeneous nucleation is operative. Furthermore, the paper is focused on the initiation and nucleation mechanisms, location of initiation locus, and growth and deactivation of latex particles. Furthermore, the relationship between kinetic and molecular weight parameters of the microemulsion polymerization process and colloidal (water/particle interface) parameters is discussed. In particular, we follow the effect of initiator and emulsifier type and concentration on the polymerization process. Besides, the effects of monomer concentration and additives are also evaluated.