磷腈
材料科学
单体
阻燃剂
高分子
分子
三聚体
化学工程
高分子化学
降级(电信)
聚丙烯
聚合物
有机化学
复合材料
化学
工程类
电信
生物化学
二聚体
计算机科学
作者
Junhua Kong,Lili Zhou,Zhi Qiao,Lei Zhang,Qi Feng Lim,Jessica Pei Wen Toh,Ming Yan Tan,Si-Hui Tan,Tingting Lin,Qiang Zhu,Warintorn Thitsartarn,Songlin Liu,Chaobin He
标识
DOI:10.1016/j.polymdegradstab.2023.110465
摘要
Cyclotriphosphazene which possesses hexafunctional framework is a versatile building block to construct functional materials and has been used in many areas such as catalysis, biomedicine, sensing and imaging, and flame retardancy. However, the proper control of the molecules and their condense state structures, in particular via the reaction of phosphonitrilic chloride trimer (PCT) with other multifunctional co-monomers is a challenge. Herein, we developed phosphazene cyclomatrix molecules using pentarythritol (PER) as the co-monomer. Through controlling the PCT/PER molar ratio and the feeding manner, the obtained product is either monomeric/oligomeric small molecules or macromolecules. Interestingly, the macromolecules self-assembled into three-dimensional structures, forming cubic nanocrystals. The thermal study shows that all molecules possess a low temperature degradation domain (LTD, 150–400 °C) and high temperature degradation domain (HTD, 500–750 °C) due to the same chemical bonds, while the macromolecules have the highest carbon forming among all. TG-IR and TG-MS results confirm the following thermal degradation features: (1) inert gases (NH3, CO2) and H2O release after 200 °C, (2) the carbonaceous phase forms at 300–450 °C when the PER segment content in the molecule is 50 % and higher, and (3) extra phosphate/phosphite agents release after 450 °C, which renders carbonizing capability. The addition of the crystalline macromolecules into polypropylene (PP) showed that under a low loading of only 18 and 22 wt%, UL94 V2 and V0 rate was achieved for the obtained composites. This indicates the high flame retardant efficacy of the macromolecules as a standalone additive, ascribing to the cooperative effect of the above thermal features in a single molecule. The synthesized macromolecule is also able to simultaneously reinforce PP in terms of tensile modulus and flexural modulus without sacrificing the impact strength and flexural strength, leading to dual functionality, i.e., enhancement flame-retardant (FR) performance and mechanical reinforcement. This study provides constructive guideline to controllably design and synthesize functional materials using this unique building block for advanced properties and applications.
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