Degradable Polystyrene via the Cleavable Comonomer Approach
Degradable Polystyrene via the Cleavable Comonomer Approach
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通过可裂解共聚单体方法可降解聚苯乙烯
DOI：
10.26434/chemrxiv-2022-78t5s
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发表时间：
2022
期刊：
影响因子：
5.5
通讯作者：
Yohann Guillaneuf
中科院分区：
文献类型：
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作者：
Noémie Gil;B. Caron;D. Siri;Julien Roche;Slim Hadiouch;Douriya Khedaioui;S. Ranque;C. Cassagne;Damien Montarnal;D. Gigmes;Catherine Lefay;Yohann Guillaneuf
聚苯乙烯 (PS) 是一种主要的商品聚合物，由于其成本低、刚度高、透明度高以及相对较高的软化温度，广泛应用于从包装到绝缘等各种应用。与所有通过自由基聚合制备的聚合物类似，PS 由 C-C 主链构成，因此不可降解。为了赋予此类材料可降解性，乙烯基单体与可进行自由基开环的环状单体的共聚是将有目的的可裂解键引入聚合物主链的有效方法。二苯并[c,e]-氧杂环庚烷-5-硫酮(DOT)是一种环状硫醇内酯单体，以其与丙烯酸酯衍生物的有效共聚而闻名，但迄今为止还无法掺入PS主链中。通过使用 PREDICI 软件结合 DFT 和动力学模型的理论研究，我们表明修改实验条件可以克服这些限制，并且可以通过将硫酯基团统计插入聚合物主链来制备高摩尔质量可降解聚苯乙烯（Mw 接近 150,000 g.mol-1）。由于良好的反应活性比仅允许随机掺入少量 mol% 的硫酯单元，因此 PS 的热性能和机械性能没有发生重大改变。使用 1,5,7-三氮杂双环[4.4.0]dec-5-ene (TBD) 作为碱，这种 PS 的降解可以在室温下的 THF 中在一小时内完成，产生 Mn 接近 1,000 g.mol-1 的低聚物。我们成功地证明了这些共聚体系在溶液中光触发 PS 分解以及合成可降解为可溶性副产物的交联 PS 网络方面的进一步适用性
Polystyrene (PS) is a major commodity polymer, widely used in various applications ranging from packaging to insulation thanks to its low cost, high stiffness and transparency as well as its relatively high softening temper-ature. Similarly to all polymers prepared by radical polymerization, PS is constituted of a C-C backbone and thus is not degradable. To confer degradability to such materials, the copolymerization of vinyl monomers with cyclic monomer that could undergo radical ring-opening is an efficient methodology to introduce pur-posely cleavable bonds into the polymer backbone. Dibenzo[c,e]-oxepane-5-thione (DOT) is a cyclic thionolac-tone monomer known for its efficient copolymerization with acrylate derivatives but so far could not be incor-porated into PS backbones. From a theoretical study combining DFT and kinetic models using the PREDICI software, we showed that modifying experimental conditions could overcome these limitations and that high molar mass degradable polystyrene (Mw close to 150,000 g.mol-1) could be prepared via statistical insertion of thioester groups into the polymer backbone. Thanks to favorable reactivity ratios allowing only a few mol% of thioester units to be randomly incorporated, there was no major modification of the thermal and mechanical properties of the PS. The degradation of such PS could be performed in THF at RT in one hour using 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) as a base, leading to oligomers with Mn close to 1,000 g.mol-1. We success-fully demonstrate further applicability of these copolymerization systems for the photo-triggered decomposi-tion of PS in solution as well as the synthesis of cross-linked PS networks degradable into soluble side-products