Synthesis and characterization of star polymers with varying arm number, length, and composition from organic and hybrid inorganic/organic multifunctional initiators
Synthesis and characterization of star polymers with varying arm number, length, and composition from organic and hybrid inorganic/organic multifunctional initiators
复制标题
DOI：
10.1021/ma9904823
复制
发表时间：
1999-10-05
期刊：
影响因子：
5.5
通讯作者：
Diamanti, S
中科院分区：
文献类型：
--
作者：
Matyjaszewski, K;Miller, PJ;Diamanti, S
由环三磷腈、环硅氧烷和有机多元醇衍生的多官能团引发剂用于原子转移自由基聚合(ATRP)合成了苯乙烯和(甲基)丙烯酸酯星形聚合物。确定了每个体系中的条件，这些条件为具有窄的单峰分子量分布的聚合物提供了线性一级动力学。相对于线型聚苯乙烯标准的相对分子质量测量表明，星形聚合物的相对分子质量低于理论预测。对聚丙烯酸丁酯样品的三重检测SEC表明，绝对相对分子质量与理论值相符--较小的相对链长是由于星形支化聚合物相对于线性类似物较低的流体力学体积。动力学参数被用来证明与引发剂结合的每个卤代烷基都参与了ATRP。制备了相对分子质量为50万、低多分散度(M-w/M-n<；1.2)的聚丙烯酸甲酯星形聚合物。还合成了具有软核和硬壳的星形嵌段共聚物。
Multifunctional initiators, derived from cyclotriphosphazenes, cyclosiloxanes, and organic polyols, were used in the synthesis of styrenic and (meth)acrylic star polymers by atom transfer radical polymerization (ATRP). Conditions were identified in each system which provided linear first-order kinetics for polymers with narrow, monomodal molecular weight distributions. Molecular weight measurements relative to linear polystyrene standards showed that the star polymers had lower molecular weights than theoretically predicted. Triple detection SEC measured on poly(n-butyl acrylate) samples demonstrated that the absolute molecular weight matched the theoretical value-the smaller relative chain length was due to lower hydrodynamic volumes of the star-branched polymers relative to Linear analogues. Kinetic arguments were used to demonstrate that each alkyl halide moiety bound to the initiators was participating in ATRP. Well-defined poly(methyl acrylate) stars of molecular weights M-n > 500 000 and low polydispersity (M-w/M-n < 1.2) have been prepared. Star-block copolymers with a soft poly(methyl acrylate) core and a hard poly(isobornyl acrylate) shell were also synthesized.