功能单体α-烯烃磺酸钠用于无皂乳液共聚合

用工业原料α-烯烃磺酸钠(AOS)作为功能单体与甲基丙烯酸甲酯(MMA)和丙烯酸丁酯(BA)进行了乳液共聚合,通过测定AOS与MAA的竞聚率,确定了适宜的聚合方式为连续加料法.使用5%AOS制备了高固含量(>60%)的胶乳,并与用十二烷基硫酸钠(SDS)作乳化剂时该体系的乳液共聚合进行了比较.AOS是影响乳液稳定性和胶粒大小的主要因素,当AOS含量为单体总质量的1%时可以得到固含量大于40%粒径小于100 nm的乳液;当AOS含量为5%时可以得到固含量大于60%的乳液.两种情况下胶粒粒径分散性均较窄,明显优于同样条件下用SDS制备的胶乳.使用1%AOS制得的胶乳静置1年后粒径及其分布基本保持不变.

SOAP-FREE EMULSION COPOLYMERIZATION OF METHYL METHACRYLATE-BUTYL ACRYLATE WITH SODIUM α-OLEFIN SULFONATES AS FUNCTIONAL MONOMER

Sodium salt of α-olefin sulfonates(AOS),a mixture of sulfonated unsaturated linear hydrocarbon with carbon numbers from C12 to C14,is used in methyl methacrylate/butyl acrylate(MMA/BA)soap-free emulsion copolymerization.The reactivity ratios of AOS-MMA are determined to be r_A=1.98 and r_M=0.034 for AOS and MMA respectively.In order to assure distribution of AOS units on the out-shell layer of the particles,a semi-continuous emulsion polymerization is used.Latex of high solids of up to 60% has been obtained with 5% AOS.And with 1% AOS,latex solids can reach to 45% with good stability,whereas this value is limited to 40% with sodium dodecyl sulfate(SDS) as surfactant.The particle size is in constant increase with latex solids combined with a sharp decrease in particle number when AOS is used;while the particle size and number of particles are kept relatively constant when SDS is used as surfactant.This is attributed to the fact that SDS can either adsorb on or desorb from the particle surface,and AOS would be fixed on a position on the particle surface once copolymerized with MMA and BA.The AOS prepared latex also shows a narrower particle size distribution,and the latex with 35% is stable after a shelf standing of up to one year.