The “solid-state” ring-opening cationic polymerization of 1,3,5-trioxane: frozen polymerization for suppression of oligomer formation and synthesis of ultrahigh molecular weight polymers,Polymer Chemistry

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The “solid-state” ring-opening cationic polymerization of 1,3,5-trioxane: frozen polymerization for suppression of oligomer formation and synthesis of ultrahigh molecular weight polymers
Polymer Chemistry ( IF 4.1 ) Pub Date : 2020-12-17 , DOI: 10.1039/d0py01401j
Chihiro Suemitsu _{1,

2,

3,

4,

5} , Arihiro Kanazawa _{1,

2,

3,

4,

5} , Sadahito Aoshima _{1,

2,

3,

4,

5}

Affiliation

The production of polyoxymethylene (POM) with higher molecular weights and lower oligomer ratios than those obtained by molten-state polymerization of 1,3,5-trioxane (TOX) was demonstrated by lowering the temperature during the polymerization or by conducting solid-state polymerization at a temperature lower than the melting point of TOX. Side reactions, such as oligomer formation, occur during the polymerization of TOX in a molten state due to the free movement of active chain ends. To suppress the side reactions, we managed the chain end mobility by conducting propagation reactions in the solid state. During “frozen polymerization”, the reaction mixture was cooled to 4, −20, or −78 °C soon after the polymerization started in a molten state. Polymers with a molecular weight M_w of over 1 million were obtained at a final temperature of 4, −20, and −78 °C. During solid-state polymerization, the reaction was started by spraying a catalyst solution onto a solid monomer, which resulted in a polymer containing negligible amounts of oligomers. In both methods, cyclic oligomer formation was suppressed, probably because the active chain end was surrounded by solid-state monomer molecules. In addition, the polymers had an extraordinarily high crystallinity and a fibrous form oriented in one direction.

中文翻译：

1,3,5-三恶烷的“固态”开环阳离子聚合：抑制低聚物形成和超高分子量聚合物合成的冷冻聚合

通过降低聚合过程中的温度或进行固态聚合，证明了与通过熔融聚合1,3,5-三恶烷（TOX）获得的聚甲醛（POM）具有更高的分子量和更低的低聚物比率在低于TOX熔点的温度下。由于活性链末端的自由运动，在熔融状态的TOX聚合过程中会发生副反应，例如形成低聚物。为了抑制副反应，我们通过在固态下进行传播反应来管理链端迁移率。在“冻结聚合”期间，聚合以熔融状态开始后不久将反应混合物冷却至4，-20或-78°C。分子量M _w的聚合物在4，-20和-78°C的最终温度下获得了超过100万的离子。在固态聚合期间，通过将催化剂溶液喷雾到固体单体上来开始反应，这导致聚合物中含有可忽略不计的低聚物。在这两种方法中，环状低聚物的形成都受到抑制，这可能是因为活性链末端被固态单体分子包围了。另外，聚合物具有极高的结晶度和在一个方向上取向的纤维形式。

更新日期：2021-01-04

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