The efficient and reliable synthesis of 2-methylene-4-phenyl-1,3-dioxolane (MPDL), a highly effective cyclic ketene acetal for radical ring-opening polymerization, was reported from three different acetal halides and thoroughly characterized by ¹H and ¹³C NMR spectroscopy, IR spectroscopy, elemental analysis and mass spectrometry. MPDL was then employed as a controlling comonomer for nitroxide-mediated polymerization using methyl methacrylate (MMA) as the principal monomer to produce well-defined, degradable PMMA-rich copolymers (M_n ∼ 20–30 kg mol⁻¹, Đ = 1.3–1.4) when sufficient MPDL was initially introduced into the monomer feed (f_MPDL,0 > 0.2). Hydrolytic degradation was tuned by varying the amount of MPDL in the monomer feed. The insertion of MPDL into the polymethacrylate backbone only moderately affected the glass transition temperature compared to the poly(methyl methacrylate) homopolymer, while giving low molar mass degradation products after hydrolysis.

中文翻译：

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有效合成环烯酮缩醛2-亚甲基-4-苯基-1,3-二氧戊环，以控制甲基丙烯酸甲酯的NMP并提供可调节的降解性†

据报道，由三种不同的乙缩醛卤化物可高效可靠地合成2-亚甲基-4-苯基-1,3-二氧戊环（MPDL），一种高效的环状烯酮缩醛，用于自由基开环聚合，其特征在于¹ H和¹³ C NMR光谱，IR光谱，元素分析和质谱。然后MPDL被用作用于氮氧化物介导，使用甲基丙烯酸甲酯（MMA）作为主单体，以产生良好限定的，可降解的富PMMA共聚物聚合（一控制共聚单体中号_Ñ〜20-30公斤摩尔^-1，Đ = 1.3- 1.4）最初将足够的MPDL引入单体进料中时（f _MPDL，0> 0.2）。通过改变单体进料中MPDL的量来调节水解降解。与聚（甲基丙烯酸甲酯）均聚物相比，将MPDL插入聚甲基丙烯酸酯骨架中仅适度影响玻璃化转变温度，而在水解后产生低摩尔质量的降解产物。