Scholarlink

<p>Herein, a ring-expansion cationic cyclopolymerization leading to the formation of macrocyclic cyclopolymers is reported. 4,4-Bis(vinyloxymethyl)cyclohexene (<b>1</b>), 5,5-bis(vinyloxymethyl)-2-bicyclo[2,2,1]heptane (<b>2</b>), 1,2-bis(vinyloxyethoxy)benzene (<b>3</b>) and 1,2-bis(2-vinyloxyethoxy)-3,5-di-<i>tert</i>-butylbenzene (<b>4</b>) were polymerized in toluene at 0 °C. A hemiacetal ester-incorporated cyclic initiator was used in conjunction with SnBr<sub>4</sub> as a Lewis acid activator in the presence of 2,6-di-<i>tert</i>-butylpyridine (DTBP) and 1,4-dioxane was used to suppress uncontrolled initiation by adventitious proton impurities. All synthesized cyclopolymers (Cyclic-Poly(<b>1</b>), Cyclic-Poly(<b>2</b>), Cyclic-Poly(<b>3</b>) and Cyclic-Poly(<b>4</b>)) were ring-shaped, with number-average molecular weights of 5000–13,000 and respective degrees of cyclization of 98.2%, 98.9%, 96.0% and 98.0%. Except for Cyclic-Poly(<b>3</b>), all the macrocyclic cyclopolymers had a high degree of cyclization exceeding 98%. Cyclic-Poly(<b>1</b>), Cyclic-Poly(<b>2</b>) and Cyclic-Poly(<b>4</b>) were soluble in solvents up to 100% monomer conversion, whereas Cyclic-Poly(<b>3</b>) was partially insoluble in the later stages of polymerization (&gt;65% monomer conversion). The glass transition temperature (<i>T</i><sub>g</sub>) was 127, 178, 98 and 136 °C for Cyclic-Poly(<b>1</b>), Cyclic-Poly(<b>2</b>), Cyclic-Poly(<b>3</b>) and Cyclic-Poly(<b>4</b>), respectively. The <i>T</i><sub>g</sub>s of the cyclic cyclopolymers were higher than those of the corresponding linear cyclopolymers.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Ring-expansion cationic cyclopolymerization of divinyl ethers: synthesis of macrocyclic cyclopolymers with 8- and 13-membered rings

  • 期刊论文

  • 发表日期：

    2025年12月17日

查看全文
  • Takeshi Namikoshi,
  • Takafumi Yamamoto,
  • Tamotsu Hashimoto,
  • Michio Urushisaki,
  • Toshikazu Sakaguchi

摘要

Herein, a ring-expansion cationic cyclopolymerization leading to the formation of macrocyclic cyclopolymers is reported. 4,4-Bis(vinyloxymethyl)cyclohexene (1), 5,5-bis(vinyloxymethyl)-2-bicyclo[2,2,1]heptane (2), 1,2-bis(vinyloxyethoxy)benzene (3) and 1,2-bis(2-vinyloxyethoxy)-3,5-di-tert-butylbenzene (4) were polymerized in toluene at 0 °C. A hemiacetal ester-incorporated cyclic initiator was used in conjunction with SnBr4 as a Lewis acid activator in the presence of 2,6-di-tert-butylpyridine (DTBP) and 1,4-dioxane was used to suppress uncontrolled initiation by adventitious proton impurities. All synthesized cyclopolymers (Cyclic-Poly(1), Cyclic-Poly(2), Cyclic-Poly(3) and Cyclic-Poly(4)) were ring-shaped, with number-average molecular weights of 5000–13,000 and respective degrees of cyclization of 98.2%, 98.9%, 96.0% and 98.0%. Except for Cyclic-Poly(3), all the macrocyclic cyclopolymers had a high degree of cyclization exceeding 98%. Cyclic-Poly(1), Cyclic-Poly(2) and Cyclic-Poly(4) were soluble in solvents up to 100% monomer conversion, whereas Cyclic-Poly(3) was partially insoluble in the later stages of polymerization (>65% monomer conversion). The glass transition temperature (Tg) was 127, 178, 98 and 136 °C for Cyclic-Poly(1), Cyclic-Poly(2), Cyclic-Poly(3) and Cyclic-Poly(4), respectively. The Tgs of the cyclic cyclopolymers were higher than those of the corresponding linear cyclopolymers.