Molecular design of melt-spinnable co-polymers as Si-B-C-N fiber precursors.
Molecular design of melt-spinnable co-polymers as Si-B-C-N fiber precursors.
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DOI：
10.1039/c7dt02559a
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发表时间：
2017-10
影响因子：
4
通讯作者：
Antoine Viard;L. Gottardo;David Lopez-Ferber;A. Soleilhavoup;C. Salameh;S. Samal;Y. Guéguen;T. Rouxel;G. Motz;F. Babonneau;C. Gervais;S. Bernard
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文献类型：
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作者：
Antoine Viard;L. Gottardo;David Lopez-Ferber;A. Soleilhavoup;C. Salameh;S. Samal;Y. Guéguen;T. Rouxel;G. Motz;F. Babonneau;C. Gervais;S. Bernard
通过二氯甲基乙烯基硅烷与二甲基硼烷的硼氢化反应，合成了通式为 [B(C2H4SiCH3(NH)x(NCH3)y)3]n 的两个系列共聚物，即由 C2H4SiCH3(NH)x 和 C2H4SiCH3(NCH3)y (C2H4 = CHCH3, CH2CH2) 结构单元以明确的 x : y 比例组成硫化物，然后根据控制的比例与氨基锂和甲胺连续反应。通过固态核磁共振、傅里叶变换红外光谱和元素分析，详细研究了其合成背后的化学作用。然后，讨论了这些聚合物的化学性质和熔体可纺性之间的密切关系。通过保持x = 0.50并将y增加到0.50以上，即获得过量的甲胺，共聚物含有更多的端基，尤其是更多的四配位硼，从而可以非常精确地调节陶瓷前体聚合物的化学结构，以满足熔体纺丝的要求。在 200 °C 的氨气下进行固化处理，可以有效地使生纤维不熔，然后在 1000 °C 的氮气下热解，生成 Si-B-C-N 陶瓷纤维。有趣的是，还可以生产具有相对较高机械性能的小直径中空纤维，以作为膜材料进行进一步探索。
Two series of co-polymers with the general formula [B(C2H4SiCH3(NH)x(NCH3)y)3]n, i.e., composed of C2H4SiCH3(NH)x and C2H4SiCH3(NCH3)y (C2H4 = CHCH3, CH2CH2) building blocks in a well defined x : y ratio, have been synthesized by hydroboration of dichloromethylvinylsilane with borane dimethyl sulfide followed by successive reactions with lithium amide and methylamine according to controlled ratios. The role of the chemistry behind their syntheses has been studied in detail by solid-state NMR, FT-IR and elemental analyses. Then, the intimate relationship between the chemistry and the melt-spinnability of these polymers was discussed. By keeping x = 0.50 and increasing y above 0.50, i.e., obtaining methylamine excess, the co-polymers contained more ending groups and especially more tetracoordinated boron, thus allowing tuning very precisely the chemical structure of the preceramic polymer in order to meet the requirements for melt-spinning. The curing treatment under ammonia at 200 °C efficiently rendered the green fibers infusible before their subsequent pyrolysis under nitrogen at 1000 °C to generate Si-B-C-N ceramic fibers. Interestingly, it could be possible to produce also low diameter hollow fibers with relatively high mechanical properties for a further exploration as membrane materials.