【摘要】 用分散共聚法制得窄分布苯乙烯(St)和丙烯酸正丁酯(nBA)的共聚物微球.采用1H-NMR、DSC、FTIR、SEM、LS等对共聚物的结构、形态、性能进行表征,考察了初始单体配比、温度、稳定剂浓度、分散介质极性、引发剂对微球粒径、粒径分布及转化率的影响.实验结果表明,初始单体比nBA/St增大,微球粒径增大,分布变宽,转化率先是小幅减小,当nBA增大到20%以上时则明显下降;当温度由60℃升高到75℃,转化率增大,微球粒径增大但分布变宽,当温度达到80℃时聚合物粒子有相互聚并的趋势,转化率由高变低;增加稳定剂用量,微球粒径减小,分布变窄,转化率变化不大;随着介质极性减小,微球粒径先是变小,分布变窄,但随后粒径增大分布变宽,当乙醇占介质质量80%～90%时,粒径分布较窄;引发剂用量增大,转化率增大,微球粒径增大,分布变宽.控制合适条件可得到表面光滑、平均粒径0.7～2μm的窄分布P(St-co-nBA)微球.更多还原

【Abstract】 Narrow-disperse poly(styrene-co-n-butyl acrylate)(P(St-co-nBA)) microspheres were prepared by dispersion copolymerization in a mixture medium of ethanol with water initiated by 2,2′-azobisisobutyronitrile(AIBN) using poly(N-vinylpyrrolidone)(PVP) as a steric stabilizer.Products were characterized by 1H nuclear magnetic resonance(1H-NMR),differential scanning calorimetry(DSC),Fourier transfer infrared spectroscopy(FTIR),scanning electron microscopy(SEM) and laser particle size analysis(LS).The influences of comonomer ratio of nBA to St(nBA/St),polymerization temperature,stabilizer content,media polarity and initiator concentration on particle size,size distribution and monomer conversion were examined.Results showed that with increasing molar ratio nBA/St,the particle size increased,but the size distribution broadened,and the monomer conversion decreased slightly,when the ratio nBA/St exceeded 20/80 it decreased rapidly.As the polymerization temperature increased from 60℃ to 75℃,the monomer conversion and the particle size all increased,but the size distribution broadened.When the temperature rised to 80℃ the particles had a tendency of merging with each other,at the same time the monomer conversion rate decreased.The content of stabilizer had no obvious effect on the monomer conversion rate,but the average size of particles decreased and the size distribution of particles narrowed with increasing the stabilizer content.The particle size and polydispersity initially decreased with the increase of EtOH/H2O ratio,passed through a minimum,and then increased.When EtOH/H2O mass ratio was 80/20 ～ 90/10,the size distribution of particles was narrow.With the increasing of initiator concentration,the monomer conversion rate and the particle size increased,while the size distribution broadened.At a well-controlled condition,the narrow-disperse particles in the size range of 0.7 ～ 2 μm were achieved.The SEM images indicated the copolymer particles were smooth on their spherical surface.The1H-NMR and FTIR spectra confirmed the polymerization between St and nBA.DSC experiments showed the glass transition temperature(Tg) of the copolymers in the range of 56.7 ～ 107.1℃.The copolymer’s composition and it’s Tg could be controlled by the ratio of the comonomers.更多还原