A method is presented to modify the degradation rates of copolymers made through vinyl- and radical ring-opening copolymerization. Six (including five novel) 7-membered cyclic allylic sulfide (CAS) lactones with varied functionality (H, ethyl, decyl, phenyl, furyl, and benzo) at the 2 (or 2/3) position were synthesized. Their radical copolymerization with hydroxypropyl methacrylamide (HPMAm), N-isopropylmethacrylamide, and oligo(ethylene glycol) methyl ether methacrylate (OEGMA) led to the inclusion of primary alkyl, secondary alkyl, benzyl, and phenyl esters into the backbone. The choice of CAS lactone comonomer allowed tuning the LCST-type cloud point of OEGMA copolymers, with substituents decreasing the cloud point in the order H < ethyl < decyl ≪ phenyl ∼ benzo. Hydrolytic degradation rate coefficients determined on HPMAm copolymers varied by a factor of 3.3, with better alcohol leaving groups leading to faster degradation. Backbone phenyl esters degraded through aminolysis, while benzyl and aliphatic esters were stable. Selective degradation was also achieved in block copolymers containing (oxo)esters in one block and thioesters (from thionolactone copolymerization) in the other. These findings demonstrate the tuning of physical properties and degradation behavior through the choice of comonomer enabling the design of degradable polymers with tailored properties.

中文翻译：

---

定制可降解聚合物：改性环状烯丙基硫化物内酯以调节聚合物降解速率并降低临界溶液温度


提出了一种改变通过乙烯基和自由基开环共聚制成的共聚物降解速率的方法。合成了 6 种（包括 5 种新型）7 元环烯丙基硫化物 （CAS） 内酯，在 2（或 2/3）位具有不同官能度（H、乙基、癸基、苯基、呋喃和苯并）。它们与羟丙基甲基丙烯酰胺 （HPMAm）、N-异丙基甲基丙烯酰胺和低聚（乙二醇）甲基醚甲基丙烯酸酯 （OEGMA） 的自由基共聚导致伯烷基、仲烷基、苄基和苯基酯加入主链中。CAS 内酯共聚单体的选择允许调整 OEGMA 共聚物的 LCST 型浊点，取代基以 H < 乙基 < 癸基≪苯基 ∼ 苯并的顺序降低浊点。在 HPMAm 共聚物上测定的水解降解速率系数变化了 3.3 倍，更好的醇留下基团会导致更快的降解。主链苯酯通过氨解降解，而苄基和脂肪族酯则稳定。在一个嵌段中含有 （氧代）酯，另一个嵌段中含有硫代酯（来自硫内酯共聚物）的嵌段共聚物中也实现了选择性降解。这些发现证明了通过选择共聚单体来调整物理性能和降解行为，从而能够设计出具有定制特性的可降解聚合物。