Preparation of chiral materials from achiral helical
polymers has
aroused great interest among researchers. In this work, chiral small
molecules were utilized to accomplish chiral induction toward racemic
helical polyacetylene via intermolecular π–π stacking
by which chiral films with strong optical activity were fabricated.
Furthermore, introducing fluorescent components generated full-color
and white circularly polarized luminescence (CPL). A CPL generation
mechanism is proposed accordingly, namely circularly polarized light
excitation (CP-Ex). CPL emission and amplification of the luminescence
dissymmetry factor were achieved under the synergetic effect of CP-Ex
and chirality transfer. The CP-Ex mechanism was further verified by
the double-layered film consisting of a chiral layer and a fluorescent
layer. More noticeably, for double-layered films, the sense of CPL
signals can be switched by changing the direction of excitation light.
This work opens up new strategies for exploring tunable multiple-
and white-color CPL materials.
Polyamide (PA) foams have been widely applied in many areas due to their outstanding properties and currently are receiving more extensive attention from the fundamental research and materials communities. However, poor melt strength and low matrix modulus seriously affect the preparation of high-performance PA foams and hinder their commercialization process. To overcome the limitations, a lot of efforts have been devoted to the research subject. In spite of the striking progress made dealing with PA foams, there has been no review to summarize the studies yet. This review begins with the consideration of the foaming process of PA and commonly used methods for PA foaming. Special emphasis is placed on effective means to enhance the performance of PA foams. Then, the typical applications of PA foams are presented, such as flame retardant, oil spill cleaning, electromagnetic shielding, and tissue engineering. Finally, the future perspective of PA foams will be outlined as well as the recommended future research directions about them.
Micro/nano-particles with surface microstructures have attracted tremendous attention due to their fascinating structures and properties. Herein, we present the first strategy for producing optically active polymer particles with varying surface...
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