Influences of Electrolytes on the Soap-free Emulsion Copolymerization of St-MMA-AA

Monodisperse functional polymer microspheres with different particle size and with clean surface were prepared by batch soap-free emulsion polymerization of styrene, methyl methacrylate and acrylic acid in the presence of salts, and the influences of type and amount of electrolytes on polymerization process and particle morphology were investigated. Results showed that there was a critical concentration for different electrolyte to make polymerization process and the resultant emulsion stable, and the particle size increased with the increase of electrolyte concentration. The effect of metal ions was Ca^2＋〉〉K^＋〉Na^＋〉Li^＋, and the effect of haloids was Br〉Cl〉F. Keywords： Electrolyte, soap-free emulsion polymerization, polystyrene, latex particle morphology.

INFLUENCES OF ACID POST-TREATMENT ON THE MORPHOLOGY OF SOAP-FREE P(MMA-EA-MAA)PARTICLES PREPARED BY SEEDED EMULSION POLYMERIZATION

Soap-free poly（methyl methacrylate-ethyl acrylate-methacrylic acid） latex particles with narrow size distribution were synthesized by seeded emulsion polymerization, and the porous particles were created by a stepwise alkali/acid treatment method. Effects of acid treatment conditions on the particle morphology were investigated. Results show that one to three pores were formed inside most of particles after post-treatment. At pH 7.0, when the treatment temperature was lower than 70℃, the size of particles and the volume of pores remained almost unchanged, and these two values increased significantly when the temperature was higher than 70℃. Both the particle size and the pore volume decreased with the increase of initial pH value and treatment time in the acid treatment. As the pH was below 4.0 and the treatment time was longer than 180 min, the particles shrunk in size.

PREPARATION AND CHARACTERIZATION OF AFFINITY POLYMER BASIC MICROSPHERES BY SOAP-FREE EMULSION POLYMERIZATION

Poly(styrene-co-glycidyl methacrylate) latex microspheres with uniform size and high-density epoxy groups on the surface were prepared by soap-free emulsion polymerization with batch wise operation mode in the presence of 2.2′- azobis(2-methylpropionamidine) dihydrochloride as an initiator.The kinetics of soap-free emulsion polymerization and the effects of polymerization factors were examined.In addition,the optimum polymerization conditions of poly(styrene-co- glycidyl methacrylate) latex microspheres for...

Preparation of Self-crosslinked Fluorocarbon Polymer Emulsion with Core-shell Structure by the Method of Soap-free Emulsion Polymerization

Using methyl methacrylate （MMA）, butyl acrylate（BA） and hexafluorobutyl acrylate（HFBA） as main raw materials, we prepared self-crosslinked fluorocarbon polymer emulsion with core-shell structure via soap-free emulsion polymerization when the conception of particle design and polymer morphology was adopted. Moreover, the influence of mole ratio of BA to MAA, pH value on the oligomer was studied. And the effects of the added amount of oligomer, self-crosslinked monomer and HFBA, mass ratio of BA to MMA, reaction temperature and the initiator on the polymerization technology and the performance of the product, were investigated and optimized. The structure and performance of the fluorocarbon polymer emulsion were characterized and tested with FTIR, TEM, MFT and contact angle and water absorption of the latex film. The experimental results show that the optimal conditions for preparing fluorocarbon polymer emulsion are as follows： for preparing the oligomer, tool ratio of BA to MAA is equal to 1.0 ： 1.60, and pH value is controlled within the range of 8.0 and 9.0; for preparing fluorocarbon polymer emulsion, the added amount of oligmer[P（BA/MANa）] is 6%; mass ratio of BA to MMA is 40 ＂ 60; the added amount of self-crosslinked monomer is 2%, the added amount of HFBA is 15 %; reaction temperature is 80 ℃; the mixture of potassium persulfate and sodium bisulfite is used as the initiator. The film-forming stability of the fluorocarbon polymer emul- sion and the performance of the latex film, which is prepared with the soap-free emulsion polymerization, are better than that prepared with the conventional emulsion polymerization.

Synthesis of submicron-sized peanut-shaped poly(methyl methacrylate)/polystyrene particles by seeded soap-free emulsion polymerization

Submicron-sized peanut-shaped poly（methyl methacrylate）/polystyrene （PMMA/PS） particles were successfully synthesized by seeded soap-free emulsion polymerization of styrene on the spherical crosslinked PMMA seed particles. The obtained peanut- shaped particles showed a novel internal morphology： PS phase formed one domain which linked to the other domain having PMMA core encased by PS shell.

PREPARATION OF MICRON-SIZED NONSPHERICAL POLYSTYRENE/POLY(STYRENE-co-ETHYLENEGLYCOL DIMETHACRYLATE) PARTICLES BY SEEDED SOAP-FREE EMULSION POLYMERIZATION

Micron-sized nonspherical polymer particles having different morphologies were synthesized by seeded soap-free emulsion polymerization of styrene （St） and ethyleneglycol dimethacrylate （EGDMA, used as a crosslinker） on spherical, linear polystyrene （PS） seed particles. The morphology of the resulting PS/poly（St-co-EGDMA） particles was dependent on the crosslinker concentration and polymerization temperature.

烷基化纳米SiO_2/MMA乳液聚合物的表征及对PC的改性效果

用TEM,FTIR分析研究了烷基化纳米SiO2/MMA乳液聚合产物的结构。结果表明,乳液聚合产物的粒子基本呈球形,由核壳组成,中心为SiO2核,外围为PMMA壳,核壳之间存在化学键。并在适量第三组分配合下能大幅度提高PC的韧性、加工流动性及耐热性,还研究了其增韧机理。

P(MMA-AN)/TiO_2复合粒子的制备及光催化性能

采用原位乳液聚合方法制备了基于共价键结合的P(MMA-AN)/TiO2复合粒子,红外光谱和热失重分析结果表明P(MMA-AN)在TiO2表面接枝率为15.9%。以甲基橙溶液为目标污染物,研究了P(MMA-AN)/TiO2复合粒子和TiO2对甲基橙的吸附和光催化降解甲基橙溶液的性能,结果表明:两种粒子对甲基橙的吸附都很少;在相同时间内,P(MMA-AN)/TiO2复合粒子对甲基橙溶液的降解性能优于TiO2,紫外光照180 min后,P(MMA-AN)/TiO2复合粒子对甲基橙溶液的降解率达到了88%,而TiO2仅为74%。

烷基化纳米SiO_2/MMA乳液聚合物及其对PC的改性研究

用乳液聚合方法制备了烷基化纳米SiO_2/MMA孔液聚合物,用TEM、FTIR分析研究了乳液聚合物的结构。结果表明,该乳液聚合物的粒子基本呈球形,由核、壳组成,中心为SiO_2核,外围为PMMA壳,核壳之间存在化学键。在适量第三组分配合下,炕基化纳米SiO_2/MMA乳液聚合物能大幅度提高PC的韧性、加工流动性及耐热性。同时对其增韧机理也进行了研究。

ChMI/MMA/St三元乳液共聚物的合成、表征及其与PVC的共混

用完全滴加料乳液共聚合方式合成了环己基马来酰亚胺/甲基丙烯酸甲酯/苯乙烯三元共聚物(ChM I/MMA/St),研究了三元共聚物的热性能、力学性能及流变性。结果显示:随着共聚单体中St含量的增加,共聚物的热分解温度明显提高;共聚物熔体表现出假塑性流体的行为,材料的表观粘度随St含量的增加而降低。同时用该三元共聚物作为耐热改性剂与聚氯乙烯(PVC)共混,研究了耐热改性剂含量对共混物热性能、力学性能、及流变性能的影响。结果表明:ChM I/MMA/St三元共聚物可以提高PVC的玻璃化温度和维卡软化温度,并能够抑制PVC的分解。

MMA-BA-AA三元乳液聚合

Methyl methacrylate（MMA）—butyl acrylate（BA）—acrylic acid（AA） copolymer emulsion was prepared by emulsion polymerization using a redox initiation system of（NH4）2SO8-NaSO3.Factor of affecting copolymerization and emulsion performance were studied.The experimental results show that the reaction rate,latex′s particle diameter and emulsion performance are affected by AA content.It is not important that the influence of composition of MMA-BA on the film forming.By seeding emulsion polymerization,copolymer emulsion stability is very well.Feeding ammonia water,the copolymer emulsion dissolved.Copolymer film is very good.

羧酸及羟基单体类型对BA-MMA-St微皂乳液聚合及性能的影响

考察了水溶性羧酸单体和羟基单体的类型对BA—MMA—St微皂乳液聚合及性能的影响。为了使水溶性单体在聚合后能有效地键合在乳胶粒表面而获得良好的稳定化作用，水溶性单体必须具有合适的亲水性，即其I／O应为2．5～5。微皂乳液涂膜的光泽及耐水性与所用水溶性单体的类型有关。联合使用MAA（或AA）和N—MA所制得的微皂乳液粒度细．所以用该乳液配制的涂料光泽比较好。采用亲水性太强的单体将使乳胶膜的耐水性变差。

BA-MMA-St的微皂乳液聚合及性能研究

通过和甲基丙烯酸及N 羟甲基丙烯酰胺共聚,成功地实现了BA MMA St的微皂乳液共聚合,使乳化剂的用量从常规乳液聚合的3.0～3.6%降到了0.05～0.10%(占单体的质量分数)。所得乳液具有粒度细(小于200nm)、固含量高(42～45wt.%)和稳定性好等特点。采用该聚合工艺明显地改善了涂膜的耐水性、硬度、拉伸强度和附着力,降低了乳液的起泡性,但也降低了涂膜的耐冲击性和延伸率。

超声辐照无皂乳液聚合制备P(AMPS-MMA)／Pd纳米复合乳液

利用超声波分散、乳化、引发、还原等作用,及单体2-丙烯酰胺基-2-甲基丙磺酸(AMPS)的特有结构,实现了超声引发AMPS、甲基丙烯酸甲酯(MMA)和氯化钯(PdC l2)的两相同步原位无皂乳液聚合,制备了纳米P(AMPS-MMA)/Pd复合粒子,考察了反应过程中pH、超声时间、超声功率对单体转化率的影响规律,并借助于FT-IR、TEM、XRD等相关分析方法对产物进行了表征.

水溶性单体类型对BA-MMA-St微皂乳液聚合的影响

通过与水溶性单体、甲基丙烯酸(MAA)、丙烯酸(AA)、N-羟甲基丙烯酰胺(N-MA)、丙烯酰胺(AM)共 聚,实现了BA-MMA-St的微皂乳液聚合。考察了水溶性单体(羧酸类单体、非离子水溶性单体)对微皂乳液聚合稳 定性和化学稳定性的影响。实验结果表明:为了使水溶性单体键合在乳胶粒表面,实现乳胶粒的稳定化,其亲水性参 数I/O应为3-5,水溶性单体还必须具有良好的聚合稳定性及与主单体良好的共聚性。

微波辐射法制备Fe_3O_4/P(MMA-AMPS)磁性微球

采用微波辐射法制备了油酸(OA)表面修饰的Fe_3O_4颗粒,透析后得到稳定的Fe_3O_4磁流体。在Fe_3O_4磁流体和十二烷基硫酸纳(SDS)的存在下,以甲基丙烯酸甲酯(MMA)和2-丙烯酰胺基-甲基丙磺酸(AMPS)为单体,采用微波辐射乳液聚合法制备了MMA-AMPS共聚物包覆Fe_3O_4磁性高分子微球,并对磁性高分子微球的形态与结构进行了表征,测定了磁性高分子微球的粒径、磁含量和饱和磁化强度。结果表明:在优化聚合反应条件下,通过微波辐射乳液聚合法可制备出粒径为0.25~0.50μm,饱和磁化强度为4.2emu·g-1的磁性高分子微球。

纳米SiO_2/MMA无皂乳液聚合研究及其应用

以纳米 Si O2 为核 ,以 MMA为壳层单体 ,进行了无皂乳液聚合。研究了单体加入方式、引发剂用量、聚合反应温度等对无皂乳液聚合的影响。核壳产物对 PVC材料的力学性能有明显的提高。

PCR-g-MMA胶粘剂的制备及粘接性能

用乳液接枝聚合法合成了氯丁橡胶（OR）／甲基丙烯酸甲酯（MMA）接枝共聚物OR-g-MMA乳液;用凝聚法制备了粉末状PCR-g-MMA干胶，将其溶于甲苯中制备了胶粘剂。研究了CR／MMA接枝聚合反应条件对单体转化率的影响和PCR-g-MMA粒子在溶剂中的溶解速率及其胶粘剂的粘接性能。结果表明，在适宜的反应条件下，接枝体系的单体转化率接近100％。SEM分析表明．PCR-g-MMA粒子表面及内部存在许多宏观及微观孔洞，使产物易于洗涤、脱水和干燥．在溶剂中有极高的溶解速率．完全溶解时间为0．5～1h。仅为片状CR248完全溶解所需时间的1／10。PCR—g—MMA胶粘剂的粘接性能与CR／MMA乳液接枝聚合反应条件有关。用其粘合PVC人造革．其初粘力为20．4N／2．5cm，剥离强度为55N／2．5cm，与片状CR248／MMA溶液接枝制备所得的胶粘剂处于相同水平。

水溶性单体类型对BA-MMA-St微皂乳液性能的影响

用甲基丙烯酸(MAA)或丙烯酸(AA)和N-羟甲基丙烯酰胺(N-MA)或丙烯酰胺(AM)共聚,实现了BA-MMA-St的微皂乳液聚合。考察了水溶性单体(羧酸类单体、非离子水溶性单体)对微皂乳液聚合性能的影响。实验结果表明,采用微皂乳液聚合明显地改善了涂膜的耐水性和附着力。