Cationic copolymerization of vinyl acetate and 3-alkoxyphthalides (ROPTs) was demonstrated to proceed using GaCl₃ as a Lewis acid catalyst. Both monomers did not undergo homopolymerization, while copolymerization smoothly occurred via the crossover reactions, resulting in alternating copolymers with molecular weights of over 10⁴. The obtained copolymers could be degraded by acid due to the cleavage of the diacyloxymethine moieties, which were derived from the crossover reactions from vinyl acetate to ROPT, in the main chain. An advantage of not radical but cationic copolymerization of vinyl esters was exerted by copolymerizations of radically reactive group-containing vinyl esters with ROPTs. For example, vinyl cinnamate was successfully copolymerized with an ROPT by the cationic mechanism, while keeping the cinnamoyl groups intact. The obtained alternating copolymer was subjected to a photodimerization reaction of the cinnamoyl groups in the side chains, resulting in an acid-degradable single-chain nanoparticle via the intramolecular crosslinking reactions.

中文翻译：

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乙烯基酯和 3-烷氧基苯酞的阳离子交替共聚：用于酸降解单链纳米颗粒的侧链可交联聚合物


证明了使用 GaCl ₃ 作为路易斯酸催化剂进行乙酸乙烯酯和 3-烷氧基苯酞 (ROPT) 的阳离子共聚。两种单体均不发生均聚，而是通过交叉反应顺利发生共聚，得到分子量超过10 ⁴ 的交替共聚物。由于主链中由乙酸乙烯酯到 ROPT 的交叉反应衍生的二酰氧基次甲基部分的裂解，所获得的共聚物可以被酸降解。通过含有自由基反应性基团的乙烯基酯与ROPT的共聚，发挥了乙烯基酯的非自由基共聚而是阳离子共聚的优点。例如，肉桂酸乙烯酯通过阳离子机制成功地与ROPT共聚，同时保持肉桂酰基团完整。所得交替共聚物的侧链肉桂酰基发生光二聚反应，通过分子内交联反应得到可酸降解的单链纳米粒子。