An Exceptionally Stable and Scalable Sugar–Polyolefin Frank–Kasper A15 Phase

“One-component” soft material Frank–Kasper (FK) phases are an intriguing structural form of matter that possess periodically ordered structures arising from the self-reconfiguration and close packing of an initial assembly of identical “deformable” spheres into two or more size- or shape-distinct sets of particles. Significant challenges that must still be addressed to advance the field of soft matter FK phases further, however, include their rare and unpredictable occurrence, uncertain mechanisms of solid-state assembly, and low thermodynamic stability. Here we show that a readily-accessible sugar–polyolefin conjugate quantitatively produces an exceptionally stable solid-state FK A15 phase through a rapid and irreversible thermotropic order–order transition, which contrary to other prevailing proposed mechanisms, does not require mass transfer between particles or large structural reorganization in the bulk to establish unit cell non-equivalency. Our results provide the basis for a realistic strategy for obtaining practical and scalable quantities of a diverse range of sugar–polyolefin FK A15 phases with unique intrinsic physical properties and chemical reactivities not previously seen in such systems.     

Sorption and diffusion of ethanol vapor in polybutadiene/acrylonitrile, polybutadiene/styrene and polybutadiene based polyurethanes

The sorption and diffusion behavior of ethanol vapor in series of polyolefine based polyurethanes (PU) made from hydroxyl-terminated polybutadiene/acrylonitrile (HTBN), hydroxyl-terminated polybutadiene/styrene (HTBS) and hydroxyl-terminated polybutadiene (HTPB) were investigated by using the quartz-spring, DSC, FTIR and AFM. The equilibrium absorption reduced with increasing content of hard segments for all the three types of PUs. The values of the maximum absorption were in the order of HTBN > HTBS > HTPB based PU and related to their composition. The non-Fickian diffusion was confirmed and the sorption was discovered mainly in the hard segments. The HTBN based PU revealed different sorption and diffusion behavior from the other two, which was resulted from its hydrogen bonding not only between ethanol and hard segments but also soft segments. The morphologies of PUs before and after ethanol absorption were also compared. The HTBN based PU showed the most evident phase re-congregation after ethanol absorption.     

聚合物气体辅助注射成型制品的形态结构

作为一种由常规注射成型发展起来的聚合物加工技术,气体辅助注射成型具有节约原材料、缩短成型周期以及提高制品性能等优点,已得到广泛的应用.由于气辅成型过程是一个在刚、柔双重约束界面条件下进行的多相复杂体系的多次流动过程,因而其形态结构的形成、发展和演化要远比常规注塑成型复杂.然而在气辅成型的形态结构方面,国内外的研究一直以来开展得较少.近年来,作者在聚合物及其共混物、复合材料气辅成型制品的形态结构方面已开展了广泛的研究工作,本文对这些工作和一些重要结果作了总结,并简要分析了成型过程中剪切场对形态演化的影响,最后对该研究方向的发展趋势作了展望.