Three-layer micelles of an ABC block copolymer:: NMR, SANS, and LS study of a poly(2-ethylhexylacrylate)-block-poly(methylmethacrylate)-block poly(acrylic acid) copolymer in D2O
Three-layer micelles of an ABC block copolymer:: NMR, SANS, and LS study of a poly(2-ethylhexylacrylate)-block-poly(methylmethacrylate)-block poly(acrylic acid) copolymer in D2O
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DOI：
10.1021/ma9708003
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发表时间：
1998-01-13
期刊：
影响因子：
5.5
通讯作者：
Doskocilova, D
中科院分区：
文献类型：
--
作者：
Kriz, J;Masar, B;Doskocilova, D
采用基团转移聚合（GTP）和酸解法制备了聚（2-乙基丙烯酸酯）-嵌段聚（甲基丙烯酸甲酯）-嵌段聚丙烯酸（PEHA-PMMA-PAAc）三嵌段共聚物。当从分子溶液转移到水或D2O中时，通过静态光散射（SLS）和动态光散射（DLS），共聚物显示为形成窄尺寸分布的球形胶束。根据核磁共振线形和信号强度分析，以及利用环己烷-d（12）选择性膨胀PEHA块体的对比度变化进行的SANS测量，三种类型的块体大多分离在一个胶束中，PEHA形成内核的内层，PMMA形成内核的外层。这两种方法都表明存在混合层，其中PEHA-PMMA（在核心）和PMMA-PAAc（在核心的外缘）相互纠缠。核磁共振数据表明PEI-IA压缩阻力与核壳界面张力之间的影响随温度的变化而变化。一般来说，溶剂对PEHA-PMMA-PAAc胶束的渗透速度比同等大小的PMMA-PAAc胶束的渗透速度要慢，但那些对PEHA有选择性的溶剂，如环己烷，在前者的情况下会使胶束核心膨胀到更高的程度。
A poly(2-ethylhexyl acrylate)-block-poly(methyl methacrylate)-block-poly(acrylic acid) (PEHA-PMMA-PAAc) triblock copolymer was prepared by group transfer polymerization (GTP) and subsequent acidolysis. When transferred from a molecular solution into water or D2O, the copolymer is shown, by static light scattering (SLS) and dynamic light scattering (DLS), to form spherical micelles of a narrow size distribution. According to NMR line shape and signal intensity analysis, and SANS measurements using contrast variation by a selective swelling of PEHA blocks with cyclohexane-d(12), the three block types are mostly segregated in a micelle, PEHA forming the inner and PMMA the outer layer of the core. Both methods indicate an existence of mixed layers in which the blocks PEHA-PMMA (in the core) and PMMA-PAAc (at the outer rim of the core) are entangled. NMR data point to the temperature-dependent conflict of the influence between the PEI-IA compression resistance and the core-shell interface tension. Solvents generally penetrate more slowly into PEHA-PMMA-PAAc micelles than into PMMA-PAAc micelles of a comparable size, but those selective for PEHA, such as cyclohexane, swell the micellar core to a higher degree in the former case.