苯乙烯-甲基丙烯酸甲酯悬浮聚合工艺优化

采用悬浮聚合法合成了苯乙烯(ST)-甲基丙烯酸甲酯(MMA)共聚物珠粒.研究了引发剂用量、搅拌速度、反应温度、分散剂用量、水与单体体积比对苯乙烯-甲基丙烯酸甲酯悬浮聚合的影响.结果表明,在ST用量为2.0mL、MMA用量为7.5 mL、水与单体体积比为6:1、1 mol·L-1 MgCl2溶液用量为2.5 mL、1 m...     

甲基丙烯酸甲酯-苯乙烯悬浮聚合共聚物粒度的控制

以过氧化二苯甲酰为引发剂,以聚乙烯醇-羟基磷酸钙复合分散体系为分散剂,采用悬浮聚合法制备甲基丙烯酸甲酯-苯乙烯共聚物珠粒.研究了单体配比、引发剂用量、分散剂用量、反应温度、搅拌速度对聚合物珠粒的影响;并用红外光谱对产物结构进行了表征.     

悬浮聚合法合成甲基丙烯酸甲酯-苯乙烯共聚物的研究

采用无机/有机三元复合分散体系进行了甲基丙烯酸甲酯与苯乙烯悬浮聚合的研究,对影响共聚物珠粒形成的因素进行了考察,得到了合成甲基丙烯酸甲酯-苯乙烯共聚物的工艺条件.用傅立叶变换红外光谱(FT-IR)方法表征了珠状共聚物的结构,并用热分析仪考察了共聚物的热性能.结果表明,在以有机蒙脱土为分散荆的优化工艺条件下,合成的甲基丙烯酸甲酯-苯乙烯共聚物的热性能有明显提高.     

甲基丙烯酸甲酯-苯乙烯共聚物的悬浮聚合工艺

采用无机／有机三元复合分散体系进行了甲基丙烯酸甲酯与苯乙烯悬浮聚合的研究。对影响共聚物珠粒形成的因素进行了考察,得到了合成共聚物的优化工艺条件。用博立叶红外光谱（FT-IR）方法表征了珠状共聚物的结构,并用热分析仪考察了共聚物的热性能。结果表明,在以有机蒙脱土为分散剂的优化工艺条件下,合成的甲基丙烯酸甲酯／苯乙烯共聚物的热性能有明显提高。     

悬浮-乳液耦合聚合制备大粒径核-壳结构PS/PMMA复合粒子

采用在苯乙烯(St)悬浮聚合不同时期滴加甲基丙烯酸甲酯(MMA)乳液聚合组分的悬浮-乳液耦合聚合方法,制备大粒径核-壳结构复合粒子。研究发现：在St悬浮聚合初期和宏观成粒基本完成的聚合后期滴加MMA乳液聚合组分,分别得到由初级粒子凝并的非核-壳结构粒子和核-壳结构不完整的复合粒子,粒径分布较宽;在St悬浮聚合中期滴加MMA乳液聚合组分,MMA和PMMA乳胶粒子易于向PS粒子扩散或粘并,制备得到平均粒径大于100gm、粒径分布窄和核-壳结构良好的PS／PMMA复合粒子。     

悬浮聚合法制取不同分子量级别的聚甲基丙烯酸甲酯

采用粉状MgCO3 作为分散剂 ,悬浮聚合制取了分子量从 2 4× 10 4 ～ 2 5 4× 10 4 的聚甲基丙烯酸甲酯。考察了温度、引发剂种类和浓度、分子量调节剂、转化率对聚合物分子量的影响规律 ,用粘度法测量了聚合物聚甲基丙烯酸甲酯 (PMMA)的分子量。结果表明 :温度的升高、引发剂浓度的增大、分子量调节剂的加入都会导致分子量的减小 ,随着转化率的提高 ,聚合物的分子量增大。在同等条件下 ,引发剂过氧化苯甲酰 (BPO)聚合所得的分子量较偶氮二异丁腈 (AIBN)高。通过实验 ,得到了满足作者需求的分子量 (96× 10 4 ～ 10 0× 10 4 )的聚合物的聚合条件为 :分散剂MgCO3 用量 1% ,单体∶水相 =1∶2 5 (质量比 ) ,引发剂BPO浓度 0 5 % ,反应温度 70℃ ,反应时间 3h。     

甲基丙烯酸甲酯-苯乙烯-马来酸酐三元共聚物的本体转移悬浮聚合法

本研究采用本体转移悬浮聚合法合成苯乙烯(ST)-甲基丙烯酸甲酯(MMA)-马来酸酐(MAH)三元共聚物。本聚合法结合了本体聚合和悬浮聚合的优点,通过本体预聚降低马来酸酐水解程度,制备了高酸酐含量的三元共聚产物,研究了引发剂、分散剂用量和预聚转化率对反应的影响,并比较不同单体比例与最终产物的性能关系。     

甲基丙烯酸甲酯-苯乙烯嵌段聚合物的RAFT聚合制备

以二硫代苯甲酸异丁腈酯为RAFT试剂,偶氛二异丁腈为引发剂,制备不同嵌段长度的甲基丙烯酸甲酯-苯乙烯嵌段聚合物.嵌段聚合物数均分子量的实验值与理论值接近,但由于RAFT聚合过程中,聚甲基丙烯酸甲酯死聚物的生成,使嵌段聚合物的分子量分布指数较宽.     

甲基丙烯酸甲酯水溶性对其悬浮均聚动力学的影响

通过比较在大水油比下的甲基丙烯酸甲酯（MMA）悬浮均聚的实验数据以及本体聚合实验结果,发现单体的水溶性对其聚合动力学有影响,不能用本体聚合动力学代替其悬浮聚合动力学。为了能更好了解单体的水溶性对其悬浮聚合动力学的影响以及影响动力学的原因,在MMA本体聚合动力学模型基础上,进一步提出3个假设：扣除溶于水相部分的单体量、增长和终止速率参数降低、少部分的油溶性引发剂被带到水相中,得到改进的悬浮聚合动力学模型,运用该模型能很好预测水油比、聚合温度、引发剂浓度等对MMA悬浮聚合动力学的影响,且与实验数据能较好吻合。     

甲基丙烯酸甲酯悬浮聚合工艺条件的研究

通过悬浮聚合法制取了聚甲基丙烯酸甲酯(PMMA)。主要研究了分散剂、引发剂、温度、搅拌速度以及水和单体的比对聚合物的影响。结果表明:当单体的量为12mL时,水和单体比为5∶1(体积比);引发剂的量为0.16g;分散剂的量为MgCl2:3mL、NaOH:6mL;温度控制在75~78℃,反应约1.5h;搅拌速度为250r/min的实验条件下,制得了颗粒均匀、透明度良好、产率较高的聚甲基丙烯酸甲酯。     

纳米铁粒子表面接枝聚合甲基丙烯酸甲酯

采用直流电弧等离子体法制备纳米铁粉,利用甲基丙烯酸(MAA)和盐酸处理纳米铁粉,通过乳液聚合方法,在纳米铁粉存在下MMA原位聚合,形成纳米铁/聚甲基丙烯酸甲酯复合粒子。分析结果表明,MMA在纳米铁粒子表面接枝聚合,纳米铁粉表面的双键参与了聚合反应,所形成的复合粒子具有核壳结构,这种复合粒子具有较高的稳定性。     

Phase behavior and properties of poly(methyl methacrylate)/poly(vinyl acetate) blends prepared via in situ polymerization

Polymer blends composed of poly(methyl methacrylate) (PMMA) and poly(vinyl acetate) (PVAc) were prepared via radical-initiated polymerization of methyl methacrylate (MMA) in the presence of PVAc. Differential scanning calorimetry and dynamic mechanical analysis were employed to investigate the miscibility and phase behavior of the blends. The PMMA/PVAc blends of in situ polymerization were found to be phase separated and exhibited a two-phase structure, although some chain transferring reaction between the components occurred. The phase separation resulted from the solvent effect of MMA during the in situ polymerization, which was confirmed by the investigation of phase behavior based on solution cast blending. Solubility analysis of the polymerized blends indicated that some chain transferring reaction between the components occurred during the polymerization. An abrupt increase in gel content from 21.2 to 72.4 wt % was observed when the inclusion of PVAc increased from 30 to 40 wt %, and the gel component consisted of the component polymers as shown by infrared spectroscopy studies. The thermogravimetric analysis study indicated that the inclusion of a small amount of PVAc gives rise to a marked stabilization effect on the thermal stability. The PMMA/PVAc blends exhibited increased notched impact properties with the inclusion of 5 wt % PVAc. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 675–684, 1998     

Kinetics of methyl methacrylate grafting polymerization onto flaky aluminum powder

With ammonium persulfate (APS) as the initiator, the kinetics of methyl methacrylate (MMA) grafting polymerization onto flaky aluminum powder (Al) was studied. It was found that the experimental apparent grafting polymerization rate, R_g = KC × C × C, was basically consistent with the theoretical result based on the theory of stable polymerization and equivalent activity, R_g = KC × C × C_MMA. The activation energy of grafting, homogenous, and total polymerization rate was calculated as 65.1, 35.4, and 37.5 kJ mol^?1, respectively. It could be validated that the relationship among these activation energies accorded with the theoretical result of parallel reactions. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

双官能团引发剂引发甲基丙烯酸甲酯的聚合速率

研究了双官能团引发剂2,5-双(2-乙基己酰过氧化)-2,5-二甲基己烷（TX-141）引发甲基丙烯酸甲酯（MMA）的自由基聚合动力学,考察了引发剂浓度、聚合温度对聚合动力学的影响.结果表明：该体系的聚合活化能为91 kJ•mol^-1左右,计算得到TX-141引发剂的分解活化能为140 kJ•mol^-1左右,与实验值接近;TX-141引发剂的反应级数约为0.72,说明MMA聚合终止基元反应中单基和双基终止并存.同时与相似半衰期的过氧化二苯甲酰（BPO）比较,发现当TX-141引发剂浓度为BPO的1/2时,两者在各个聚合温度下的聚合动力学曲线几乎相同;但相对分子质量有明显增加,随聚合转化率增加,TX-141与BPO引发的聚合物数均分子量之比从1.2变化到1.33;由TX-141引发的聚合物低转化率时DSC曲线出现放热峰,而高转化率以及BPO引发的聚合物则没有.说明双官能团引发剂TX-141引发聚合时,在低转化率下TX-141引发剂的2个过氧键没有全部断裂,随聚合进行,断裂程度加深.     

原子转移自由基聚合法合成PS-g-PMMA

以氯乙酰化聚苯乙烯微球（PS-acyl-Cl）为大分子引发剂,甲基丙烯酸甲酯（MMA）为单体,CuCl/CuCl₂及N,N,N′,N′-四甲基乙二胺（TMEDA）为催化体系的原子转移自由基聚合反应,成功在PS-acyl-Cl表面接枝上PMMA分子链而获得聚苯乙烯 接枝 聚甲基丙烯酸甲酯（PS-g-PMMA）。考察了催化剂、反应温度、溶剂用量等条件对接枝反应的影响,优化的反应条件下,使用氯乙酰基担载量3.44 mmol.g^-1的PS-acyl-Cl,15 h可获得增重率687% 的PS-g-PMMA,且反应表现出一级动力学特征（k=513×10^-5 s^-1）。通过改变反应条件,可得到不同PMMA接枝链长的PS-g-PMMA。反应得到的PS-g-PMMA经水解后有望作为高担载量弱酸型离子交换树脂或进一步功能化后作为酶的柔性固定化载体。     

Microemulsion polymerization of methyl methacrylate initiated with γ ray

Polymerization of methyl methacrylate was studied in an oil and water microemulsion stabilized with styrene 12-butinoyloxy-9-octadecenoic acid. During the polymerization the size change of the monomer-swollen particles with conversion was measured with photon correlation spectroscopy, and the hydrodynamic diameter of the final polymer latex was about 50 nm. The polymerization kinetics in this microemulsion were also investigated. The apparent plateau of the polymerization rate was observed at a low dose rate and high emulsifier content. The mechanism leading to this plateau was discussed. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2621–2626, 1999     

聚苯乙烯-聚甲基丙烯酸甲酯核-壳粒子的制备

由种子乳液聚合法制备了聚苯乙烯-聚甲基丙烯酸甲酯核-壳粒子。以过硫酸钾(KPS)为引发剂,辛基酚聚氧乙烯醚(OP-10)为乳化剂,合成了聚苯乙烯(PS)种子核;连续滴加甲基丙烯酸甲酯(MMA),在核表面富集MMA,制备了粒径范围在0.16~0.67μm的核-壳粒子;当单体苯乙烯与甲基丙烯酸甲酯(St/MMA)的比为30∶70(质量比)时,所得粒径在0.18μm,粒径分布为0.012。差示扫描量热(DSC)研究显示,复合粒子的玻璃化转变温度(Tg)为97.2℃,峰形单一,表现出良好的热性能。     

Photo‐induced controlled radical polymerization of methyl methacrylate mediated by photosensitive nitroxides

Photosensitive nitroxides bearing different chromophore groups (benzophenone, naphthalene and quinoline) were synthesized and characterized. The photochemical properties of the synthesized products were investigated by UV?visible and fluorescence measurements. The results indicated that an efficient energy transfer from the chromophore moiety to the nitroxide radical moiety could occur within the molecular distances. The photo‐induced nitroxide‐mediated polymerization of methyl methacrylate (MMA) was performed using the photosensitive nitroxide/2,2‐dimethoxy‐2‐phenyl acetophenone as a bimolecular mediated system. The controlled character of the polymerization was confirmed by the linear tendency of molecular weight evolution with narrow molecular weight distribution (1.3?1.4). The experimental conditions, such as type of chromophore, initiator concentration and molar ratio of initiator/nitroxide, are discussed for a better understanding of the mechanism of the controlled polymerization. Using the polymerization products as macroinitiator, the chain extension reaction of MMA turned out to be able to re‐initiate further polymerization of the monomer. © 2014 Society of Chemical Industry     

Morphological characterization of attapulgite/poly(methyl methacrylate) particles prepared by soapless emulsion polymerization

BACKGROUND: The synthesis of core–shell inorganic/polymer nanocomposites, in which the polymer shell determines the chemical properties and the interaction with the environment, whereas their physical properties are governed by both the size and shape of the inorganic core and the surrounding organic layer, is an area of increasing research activity. RESULTS: Core–shell and bead–string shaped attapulgite/poly(methyl methacrylate) (ATP/PMMA) nanocomposite particles were prepared by soapless emulsion polymerization in an aqueous suspension of attapulgite organically modified with cetyltrimethylammonium bromide. CONCLUSION: Transmission electron microscopy analysis results showed that the amounts of the monomer added had no influence on the morphologies of the ATP/PMMA particles. The morphologies only depended on the length/diameter ratio of the attapulgite fibrillar single crystal used. Long ATP needles formed the bead–string structure while short ATP needles formed the core–shell structure. Copyright © 2007 Society of Chemical Industry