丙烯酸钠反相浮液聚合

以阴离子乳化剂制备丙烯酸钠反应相乳液，用γ射线引发其聚合，用扫描电镜观测了聚合前后粒径的变化；并在聚合过程中改变剂量率观测了聚合速率的变化，这两个实验结果都显示聚合以液滴成核为主，即聚合机理类似于悬浮聚合，与以司盘８０为乳化剂的丙烯酸钠反相乳液聚合相比，体系与司盘体系的聚合动力学基本相似。     

悬浮-乳液复合聚合聚苯乙烯-聚甲基丙烯酸甲酯复合粒子的颗粒特性和成粒机理

采用在苯乙烯 (St)悬浮聚合过程中滴加甲基丙烯酸甲酯 (MMA)乳液聚合组分的悬浮 乳液复合聚合方法 ,制备大粒径聚苯乙烯 聚甲基丙烯酸甲酯 (PS PMMA)复合粒子 .研究聚合物粒径分布和颗粒形态的变化发现 ,在St悬浮反应中期滴加MMA乳液聚合组分后 ,聚合体系逐渐由悬浮粒子与乳胶粒子并存向形成单峰分布复合粒子转变 ,最终形成核 壳结构完整的大粒径PS PMMA复合粒子 ;在St悬浮反应初期滴加MMA乳液聚合组分 ,St与MMA一起分散成更小液滴 ,反应后期凝并成非核 壳结构复合粒子 ;在St悬浮反应后期滴加MMA乳液聚合组分 ,PMMA乳胶粒子与PS悬浮粒子基本独立存在 .根据以上结果 ,提出了St MMA悬浮 乳液复合聚合的成粒机理 .     

过硫酸钾引发丙烯酰胺微乳液聚合

以山梨醇酐单月桂酸醋（Ｓｐａｎ２０）和聚氧乙烯山梨醇酐单硬醋酸酯（Ｔｗｅｅｎ６０）的混合物为乳化剂制备丙烯酰胺微乳液，研究了体系中Ｔｗｅｅｎ６０浓度、水相丙烯酰胺浓度对微乳液电导行为的影响．用过硫酸钾引发微乳液聚合，发现聚合开始后，体系电导率迅速下降，在聚合进入恒速期后电导不再降低．聚合的动力学表达式为：Ｒｐ∝［ＡＭ］１．１７［Ｅ］－１．２６［Ｉ］０．５；Ｍｖ∝［ＡＭ］１．０５［Ｅ］－０．９４［Ｉ］－０．６２．它与常规乳液聚合的动力学相差较大，却类似于悬浮聚合．     

过硫酸钾引发苯乙烯微乳液聚合

以具有Ｙ型结构的乳化剂ＨＯＡ制备苯乙烯微乳液，能有效提高体系中单体浓度和单体对乳化剂的比例，用过硫酸眼具有苯乙烯含量较高的微乳液聚合，记录聚合速率随转化率的变化，观测到了聚合恒速期的存在，恒速期随单体浓度减小，过硫酸钾浓度增加及乳化剂浓度增加而缩短，还研究了聚合动力学，探讨了微乳液聚合的机理。     

丙烯酰胺反相悬浮聚合

文献上对丙烯酰胺的反相乳液聚合、反应机理和动力学模型的报道较多,有关反相悬浮聚合则报道甚少。Dimonie等考察了引发剂浓度、水相加入的方式等对聚合物分子量的影响。本实验以石油醚为连续相,聚乙烯醇、司班-20及司班-80为分散剂,K_2S_2O_8为引发剂组成反相悬浮聚合体系,所得聚丙烯酰胺呈明显的颗粒状,极易与溶剂分离且转化率高,分子量大。 所用试剂有:丙烯酰胺(CP,天津化学试剂研究所);过硫酸钾(AR,上海试剂二厂);聚乙烯     

氧化-还原低温引发苯乙烯/丙烯酸丁酯细乳液共聚合动力学与成核机理的研究

详细讨论了 [(NH4 ) 2 S2 O8/NaHSO3 ]氧化 还原引发体系引发苯乙烯 (St)丙烯酸丁酯 (BuA)体系的细乳液共聚合的动力学特征及其与成核机理的关系 .细乳液的聚合速率比相同条件下的常规乳液聚合速率低 ,引发期长 .随聚合温度、引发剂浓度、乳化剂浓度的增加 ,聚合速率增大 .共乳化剂正十六烷 (HDE)的浓度在一定范围内增大 ,反应的速率增大 ,然后再增加HDE ,反应速率下降 .建立动力学曲线数学模型 ,并深入讨论了细乳液的聚合动力学特征 ,与常规乳液所得结果相比较 ,探讨了细乳液的单体液滴成核机理 .     

丙烯酰胺双水相聚合体系稳定性研究

通过浊点滴定法测定了不同温度下PAAmPEGH2O双水相体系相图,发现分相浓度随着温度的升高先增后降,55℃时分相浓度最低.双水相聚合体系微观结构显示,分散相以砾状液滴形式均匀分散在连续相中.研究了聚合过程中聚合体系粘度的变化,以及聚合温度、分散介质、单体、引发剂及乳化剂等对聚合体系最终粘度的影响,聚合体系最终粘度在一定范围内随分散介质和单体浓度增加变化不大,但是超过某一浓度后聚合体系粘度急剧增加;聚合体系中加入少量乳化剂对体系粘度影响不大,但加入大量乳化剂后体系稳定性变差,聚合体系粘度急剧增加;聚合体系最终粘度随着聚合温度升高先降后增,与相图的预测结果一致.     

以两性高分子作反相悬浮稳定剂合成吸水剂

以聚（甲基丙烯酸十二酯－丙烯酸）两性共聚物为稳定剂，用反相悬浮聚合法合成了丙烯酸／丙烯酰胺／甲基丙烯酸羟乙酯三元共聚型超强吸水剂：吸蒸馏水1150mL.g^-1，吸0．9％NaCl溶液91mL.g^-1，研究了稳定剂结构及用量，单体组成，交联剂，链转移剂，中和程度等聚合条件及吸水剂性能的影响，实验表明甲基丙烯酸十二酯－丙烯酸共聚物是一种很好的反相悬浮稳定剂。     

丙烯酰胺微乳液聚合

由乳化剂聚乙二醇壬基苯基醚ＯＰ、聚乙二醇壬基苯基醚（ＴＸ—４）、丙烯酸胺、水和煤油组成微乳液时，体系中水相丙烯酸胶浓度及体系温度对乳化剂最小量有明显的影响；而ＯＰ、ＴＸ—４比例及油水比例的影响不大．本文研究了辐射引发微乳液聚合的动力学，得到如下表达式：聚合速率及聚合物特性粘数的表观活化能分别为５３．２ＫＪ／ｍｏｌ，－３３．２ＫＪ／ｍｏｌ．聚丙烯酸胺微乳液具有特殊的增稠性能，与聚电解质增稠剂相比，电解质对增稠效果的影响不大，而其他表面活性剂的影响较大．     

反相悬浮聚合法合成超强吸水剂

以两性高分子作悬浮稳定剂，用反相悬浮聚合法合成了聚（丙烯酸盐－丙烯酰胺）类超强吸水剂．研究了交联剂、稳定剂、引发剂等用量、中和程度、单体组成及链转移剂等聚合条件对吸水剂吸水性能的影响．得到了吸蒸馏水１０５０ｍＬ／ｇ及吸０．９％ＮａＣｌ溶液８６ｍＬ／ｇ的超强吸水剂．此外，还比较了含不同反离子的聚丙烯酸类吸水剂的吸水性能     

Kinetics of the potassium persulfate-initiated inverse emulsion polymerization of sodium acrylate solutions

The kinetics of the K₂S₂O₈-initiated inverse emulsion polymerization of aqueous sodium acrylate solutions in kerosene with Span 80 as the emulsifier has been studied. The conversion-time curves are S-shaped. The following expressions have been obtained for the maximum rate of polymerization and the molecular weight of the polymers under the experimental conditions investigated: R_max ∞ [K₂S₂O₈]^0.78[sodium acrylate]^1.5[Span 80]^0.1, (OVERLINE)M(/OVERLINE)_u ∞ [K₂S₂O₈]^−0.37[sodium acrylate]^2.9[Span 80]^−0.2. The activation energy for the maximum rate of polymerization is 94.8 kJ mol^−1. The results suggest a monomer–droplet–nucleation mechanism for the system studied. © 1996 John Wiley & Sons, Inc.     

UV光引发的丙烯酰胺反相乳液聚合

报道了不透明丙烯酰胺反相乳液体系的UV光引发聚合新方法 .使用普通中压汞灯并辅以适当搅拌 ,UV光引发丙烯酰胺 水 煤油 Span80 +OP 10反相乳液聚合可在 2 0min左右完成 ,所得聚合物分子量达千万 ;聚合过程中不存在恒速期 ,扫描电镜未观察到聚合前后乳胶粒径有数量级的变化 ,表明聚合反应以单体液滴成核为主 .此外 ,考察了光引发剂类型及浓度、单体浓度、乳化剂用量、反应温度等对聚合反应的影响 ,结果表明不同光引发剂的引发活性为Irgacure 2 95 9>(ITX +EDAB) >BDK ,引发剂浓度增加 ,反应速度先增加而后降低 ,存在一最大值 ;单体浓度增加 ,反应速度加快 ,聚合物分子量提高 ;乳化剂用量增加 ,反应速度加快而分子量变化不明显 ;聚合表观活化能为 13 34kJ mol.     

反相乳液共聚合制备两性丙烯酰胺共聚物的研究

采用Span80-Tween80复合乳化剂和AIBA引发剂,进行丙烯酸钠(NaAA)/丙烯酰胺(AM)/丙烯酰氧基乙基三甲基氯化铵(DAC)反相乳液共聚合.研究了聚合温度、引发剂用量、单体浓度、共聚单体中DAC和AM含量、乳化剂用量及其HLB值、水/油比和水相pH值等聚合反应工艺条件或参数对聚合反应单体转化率和聚合物特性粘度的影响,聚合物特性粘度随引发剂用量和单体浓度的增大而增大的实验结果证实了该两性丙烯酰胺共聚物反相乳液制备过程中凝胶效应的存在.傅立叶红外光谱组成分析表明了两性丙烯酰胺共聚物的成功合成,扫描电镜观测乳胶粒粒径范围在0.6~8.0μm.     

离心系数表征丙烯酰胺反相乳液的稳定性

用丙烯酰胺反相乳液经离心处理后保留的乳液体积与原乳液体积之比（离心系数Vr）考察了丙烯酰胺及其衍生物反相乳液的稳定性。 结果表明,离心系数Vr越大,其乳液的稳定性越好。 在高速离心条件下,由Span80/Span85和Tween80构成的丙烯酰胺及其衍生物反相乳液的Vr与油相质量分数存在正相关的关系。 在油相质量分数确定的情况下,离心系数Vr不仅与3种表面活性剂构成的亲水亲油平衡值（HLB）有关,而且与丙烯酰胺及其衍生物的浓度和类型有关。 HLB值在4.20左右时,乳液是稳定的;随丙烯酸氧乙基三甲基氯化铵（DAC）在水相中质量分数的提高,反相乳液稳定性增强,w(DAC)＞24%时可得到稳定乳液。 在15000 r/min离心3 min,Vr=0.95以上的丙烯酰胺及其衍生物反相乳液很稳定,静置半年仍未出现分层现象。     

Poly(methyl methacrylate) hollow particles by water-in-oil-in-water emulsion polymerization

Poly(methyl methacrylate) particles having hollow structures were produced by water-in-oil-in-water (W/O/W) emulsion polymerization where sorbitan monooleate (Span80) was used as a primary surfactant and sodium laurylsulfate and Glucopen (APG, polypeptide derivative) were used as secondary surfactants. Urethane acrylate having a molecular structure with a hard segment in the molecular backbone, a long soft segment in the middle, and vinyl groups at both ends was employed as a reactive viscosity enhancer. At low concentration of urethane acrylate, only a few particles contained a void in the polymer phase. However, as the concentration of urethane acrylate increased, the number of the particles containing the void increased. This was because urethane acrylate increased the viscosity of the monomer mixture and helped to form the stable W/O/W emulsion droplets, which possibly restricted droplet coalescence during emulsion polymerization. Moreover, at high concentration of urethane acrylate (above 7 wt%), multi-hollow-structured particles were obtained. It is believed that the increase in the lyophilicity of the monomer mixture caused by urethane acrylate led to stronger interfacial activity of the primary surfactant (Span80) and finally resulted in many internal aqueous droplets. Received: 31 July 1998 Accepted: 13 October 1998     

表面活性单体存在下的MMA/BA乳液共聚合(Ⅱ)聚合动力学及机理

研究了表面活性单体[磺化-十二醇-烯丙基甘油-丁二酸酯钠盐(ZC-L)]的用量对MMA/BA/ZC-L乳液聚合速率和粒径的影响,用CoulterLS230型激光粒径分析仪测定聚合过程中乳液的粒径和粒径分布变化,并与MMA/BA无皂乳液聚合及十二烷基苯磺酸钠存在下的MMA/BA乳液聚合作了比较.[ZC-L]CMC时,成核机理包括均相成核和胶束成核机理,生成的粒子因吸收体系中的表面活性单体而稳定存在.     

表面活性单体存在下的MMA／BA乳液共聚合（Ⅱ）：聚合动力？…

研究了表面活性单体「磺化－十二醇－烯丙基甘油－丁二酸酯钠盐（ＺＣ－Ｌ）」的用量对ＭＭＡ／ＢＡ／ＺＣ－Ｌ乳液聚合速率和粒径的影响,用Ｃｏｒｌｔｉｒ ＬＳ２３０型激光粒径分析仪测定聚合过程中乳液的粒径和粒径分布变化,并与ＭＭＡ／ＢＡ无皂乳液聚合及十二烷基苯磺酸钠存在下的ＭＭＡ／ＢＡ乳液聚合作了比较。「ＺＣ－Ｌ」〈ＣＭＣ时,成核机理为均相成核机理,乳胶粒需依靠粒子间的凝聚来提高表面电荷密度而稳定;「ＺＣ     

Formation and stability of paraffin oil-in-water nano-emulsions prepared by the emulsion inversion point method

Paraffin oil-in-water nano-emulsions stabilized by Tween 80/Span 80 were prepared using the emulsion inversion point method at different emulsification temperatures. Nano-emulsions with droplet size below 200 nm were formed above a critical surfactant-to-oil ratio of 0.20 at 50 degrees C. The main destabilization mechanism of the systems was found to be Ostwald ripening. An interesting phenomenon was that the Ostwald ripening rate declined as the surfactant concentration rose. Furthermore, flocculation was also found to contribute to the instability of the nano-emulsions, especially for those with low surfactant concentrations. Study on the electrophoretic properties of emulsion droplets revealed a negative value of the zeta potential, which was strongly dependent on the pH of the systems.     

Preparation of poly(acrylamide)/nanoclay organic-inorganic hybrid nanoparticles with average size of ∼250 nm via inverse Pickering emulsion polymerization

In this study, the preparation of poly(acrylamide)/nanoclay organic-inorganic hybrid nanoparticles via surfactant-free inverse emulsion polymerization by using organically modified clay platelets as stabilizers was discussed. Colloidally stable inverse Pickering emulsions of aqueous acrylamide solution in cyclohexane (solvent) stabilized by hydrophobic Cloisite 20A (MMT20) were prepared. Polymerization was carried out via 2,2′-azobis(isobutyronitrile) and composite particles with an average size of ～250 nm were obtained. The effect of initiator and solvent type on the stability, size, size distribution, and morphology of the produced composite particles was examined. It was observed that in the presence of xylene as solvent, particles with bigger sizes and broader size distribution were obtained. Furthermore, using an ionic initiator resulted in a slight coagulation during polymerization and smaller particles. Moreover, the effect of various polymerization conditions such as temperature, initiator, and crosslinking agent concentration and clay content on the polymerization rate was evaluated. The experimental results showed that polymerization rate increases with an increase in polymerization temperature, crosslinking agent concentration, and initiator content. However, increasing in clay content results in a lower polymerization rate.     

Preparation of hemispherical polyimide particles by inverse emulsion technique from poly(amic acid) ammonium salts

Nonspherical polymer particles have attracted increasing attention recently. In this paper, micron-scale hemispherical polyimide (PI) particles were fabricated using water-soluble poly(amic acid) ammonium salts (PAAS) by a novel inverse emulsion technique. In the process, liquid paraffin was used as a continuous phase, the mixed solution of PAAS and water as a dispersed phase and sorbitan monooleate (Span80) as a surfactant. The research suggested that water as a stabilizing agent played an important role in forming stable emulsion. As the amount of water increased, stability of the emulsion increased gradually and morphology of PI particles transformed from sphere to ellipsoid, and finally to hemisphere. The concentration of PAAS solution and Span80 both affected the shape of particles, which changed from spherical to hemispherical by increasing the PAAS/Span80 concentration. The mechanism of forming hemispherical PI particles was discussed based on interfacial tension and interfacial free energy changes. Via adjusting the composition of the system to change the corresponding interfacial tension, we could get the particles with different morphologies. Furthermore, the change in structure characterized by FT-IR spectroscopy demonstrated that PAAS had been converted to PI after adding the dehydrating agent to the emulsion. And TGA results showed that the obtained PI particles had excellent thermal stability.