Dispersion Polymerization of Acrylamide
Dispersion Polymerization of Acrylamide
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DOI：
10.1021/la9605044
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发表时间：
1997-04
期刊：
影响因子：
3.9
通讯作者：
B. Ray;B. Mandal
中科院分区：
文献类型：
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作者：
B. Ray;B. Mandal
以聚乙烯基甲醚(PVME)为聚合物稳定剂，过硫酸铵为引发剂，在叔丁醇(TBA)水溶液中成功地进行了丙烯酰胺的分散聚合。形成了多分散的球形和椭圆形颗粒。球形和椭圆形颗粒的同时存在表明，类似尺寸的颗粒发生了聚合(均聚)，导致了多分散性。随着稳定剂浓度的增加，粒径减小，相对分子质量增大。引发剂浓度的增加导致粒子尺寸的增大和相对分子质量的减小。这些观察结果与文献中报道的其他分散聚合反应一致。粒径随着TBA浓度的增加而减小，即随着介质极性的减小而减小。TBA-水混合物对PVME表现出共溶解作用，其溶解能力在TBA体积分数为70%左右时达到最大。这一偿付能力方面不能解释随着TBA浓度的增加而单调地减小颗粒尺寸的原因。颗粒直径(Dn)与介质的初始溶解度参数(δ)的关系图给出了一条直线，与已报道的非极性单体在极性溶剂中分散聚合的Dn与1/δ之间的线性关系不同。如果接枝的聚合物起到真正的稳定剂的作用，这两种体系的行为差异就可以被调和。
Dispersion polymerization of acrylamide has been successfully carried out in aqueous tert-butyl alcohol (TBA) media (TBA = 50 - 80 vol %) using poly(vinyl methyl ether) (PVME) as the polymeric stabilizer and ammonium persulfate as the initiator. Polydisperse spherical as well as oval particles are formed. The simultaneous presence of both spherical and oval particles suggests the coalescence of similar size particles (homocoalescence) takes place, leading to polydispersity. The increase of stabilizer concentration leads to a decrease in particle size and an increase in molecular weight. An increase of initiator concentration results in an increase in particle size and a decrease in molecular weight. These observations are in conformity with other dispersion polymerizations reported in the literature. Particle size decreases as the TBA concentration increases, i.e. as the medium polarity decreases. TBA-water mixtures exhibit cosolvency toward PVME, the solvency becoming highest at about 70 vol % TBA. This solvency aspect cannot account for the monotonous decrease of particle size with an increase in TBA concentration. A plot of particle diameter (D n ) vs the initial solubility parameter (δ) of the medium gives a straight line unlike the linear relationship between D n and 1/δ reported for dispersion polymerization of nonpolar monomers in polar solvents. This difference in behavior for the two systems can be reconciled ifthe grafted polymer acts as the true stabilizer.