共聚物
胶束
材料科学
环氧乙烷
化学工程
环氧丙烷
等温滴定量热法
高分子化学
动态光散射
水溶液
相(物质)
差示扫描量热法
热力学
聚合物
化学
物理化学
有机化学
纳米颗粒
复合材料
纳米技术
物理
工程类
作者
An-Sofie Huysecom,Christ Glorieux,Jan Thoen,Wim Thielemans,Charles‐André Fustin,Paula Moldenaers,Ruth Cardinaels
标识
DOI:10.1016/j.jcis.2023.03.013
摘要
The micellization of block copolymers of poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO) is driven by the dehydration of PPO at elevated temperatures. At low concentrations, a viscous solution of isolated micelles is obtained, whereas at higher concentrations, crowding of micelles results in an elastic gel. Alternating PEO-PPO multiblock copolymers are expected to exhibit different phase behavior, with altered phase boundaries and thermodynamics, as compared to PEO-PPO-PEO triblock copolymers (Pluronics®) with equal hydrophobicity, thereby proving the pivotal role of copolymer architecture and molecular weight.Multiple characterization techniques were used to map the phase behavior as a function of temperature and concentration of PEO-PPO multiblock copolymers (ExpertGel®) in aqueous solution. These techniques include shear rheology, differential and adiabatic scanning calorimetry, isothermal titration calorimetry and light transmittance. The micellar size and topology were studied by dynamic light scattering.Multiblocks have lower transition temperatures and higher thermodynamic driving forces for micellization as compared to triblocks due to the presence of more than one PPO block per chain. With increasing concentration, the multiblock copolymers in solution gradually evolve into a viscoelastic network formed by soluble bridges in between micellar nodes, whereas hairy triblock micelles jam into liquid crystalline phases resembling an elastic colloidal crystal.
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