Legros Camille, De Pauw-Gillet Marie-Claire, Tam Kam Chiu, Taton Daniel, Lecommandoux Sébastien
Université de Bordeaux/IPB, ENSCBP, 16 Avenue Pey Berland, 33607 Pessac Cedex, France.
Soft Matter. 2015 May 7;11(17):3354-9. doi: 10.1039/c5sm00313j.
The solution behaviour in water of a polyoxazoline-type block copolymer, namely poly(2-isopropyl-2-oxazoline)-block-poly(2-methyl-2-oxazoline), denoted as P(iPrOx-b-MeOx), above the lower critical solution temperature (LCST) of the PiPrOx block was exploited to induce a temporary or permanent self-assembly. Spherical micelles were first obtained and could be disassembled in a reversible manner when kept for a short period of time (i.e. t < 90 min) above the LCST, and cooled down to room temperature. In contrast, annealing the copolymer solution for more than 90 min at 65 °C induced the crystallisation of the PiPrOx block, as evidenced by wide angle X-ray scattering (WAXS) experiments. This crystallisation-driven self-assembly phenomenon resulted in different morphologies, including spherical and distorted crystallised micelles and micron-size fibers, their relative proportion varies with the annealing time. Formation of micron-size range fiber-like structures might be explained by the re-organization of parent crystallised micelles. The crystal structure, as determined by WAXS, appeared to be identical to that of the PiPrOx homopolymer.
聚恶唑啉型嵌段共聚物，即聚（2-异丙基-2-恶唑啉）-嵌段-聚（2-甲基-2-恶唑啉），记为P（iPrOx-b-MeOx），在PiPrOx嵌段的低临界溶液温度（LCST）以上在水中的溶液行为被用于诱导临时或永久自组装。首先获得球形胶束，当在LCST以上短时间（即t < 90分钟）保持并冷却至室温时，它们可以以可逆方式分解。相反，在65°C下将共聚物溶液退火超过90分钟会诱导PiPrOx嵌段结晶，广角X射线散射（WAXS）实验证明了这一点。这种结晶驱动的自组装现象导致了不同的形态，包括球形和扭曲的结晶胶束以及微米尺寸的纤维，它们的相对比例随退火时间而变化。微米尺寸范围的纤维状结构的形成可能是由母体结晶胶束的重组来解释的。由WAXS确定的晶体结构似乎与PiPrOx均聚物的晶体结构相同。
