Biobased poly(γ-butyrolactone) (PγBL) as a fully biodegradable and bioabsorbable biomaterial has shown superior properties compared to those of other aliphatic polyesters. It is of great importance to prepare amphiphilic block copolymer containing PγBL block to make ordered nano-objects for biomedical applications such as drug delivery systems. However, such an amphiphilic copolymer containing PγBL segment was never successfully prepared mostly due to the synthetic challenges of ring-opening polymerization (ROP) of nonstrained γ-butyrolactone (γBL) monomer. Here, we reported the first preparation of amphiphilic poly(ethylene glycol)- b-poly(γ-butyrolactone) (PEG- b-PγBL) diblock copolymer by using PEG as a macroinitiator. We applied two types of bases to initiate the ROP of γBL. An organic cyclic trimeric phosphazene base (CTPB) was first applied to activate the terminal hydroxyl group of PEG as macroinitiator for ROP of γBL. On the other hand, sodium hydride was used to activate the hydroxyl group of PEG to form sodium alkoxide as an initiating system for ROP of γBL. Both catalytic/initiating system showed moderate control on ROP of γBL and successfully produced PEG- b-PγBL diblock copolymers with varied molecular weights and relatively narrow molecular weight distributions. The effects of catalytic systems, activation temperatures, and monomer concentrations on γBL conversion and molecular weight of PEG- b-PγBL were carefully explored. The thermal properties and phase behaviors of obtained PEG- b-PγBL were also investigated.

中文翻译：

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环状三聚芴基或碱式醇盐催化开环聚合制备两亲性聚（乙二醇）-b-聚（γ-丁内酯）二嵌段共聚物。

与其他脂肪族聚酯相比，生物基聚（γ-丁内酯）（PγBL）作为一种完全可生物降解和可生物吸收的生物材料，具有优越的性能。制备含PγBL嵌段的两亲嵌段共聚物以制备用于生物医学应用如药物递送系统的有序纳米物体是非常重要的。然而，这种含PγBL链段的两亲共聚物从未成功制备，这主要是由于非应变γ-丁内酯（γBL）单体的开环聚合（ROP）的合成挑战。在这里，我们报道了使用PEG作为大分子引发剂，首次制备两亲性聚（乙二醇）-b-聚（γ-丁内酯）（PEG-b-PγBL）二嵌段共聚物。我们应用了两种类型的碱基来启动γBL的ROP。首先使用有机环状三聚磷腈碱（CTPB）活化PEG的末端羟基，作为γBLROP的大分子引发剂。另一方面，氢化钠用于活化PEG的羟基以形成醇钠，作为γBLROP的引发体系。两种催化/引发体系均显示出对γBL的ROP的适度控制，并成功生产了分子量可变且分子量分布相对较窄的PEG-b-PγBL双嵌段共聚物。仔细研究了催化体系，活化温度和单体浓度对PEG-b-PγBL的γBL转化率和分子量的影响。还研究了所得PEG-b-PγBL的热性质和相行为。另一方面，氢化钠用于活化PEG的羟基以形成醇钠，作为γBLROP的引发体系。两种催化/引发体系均显示出对γBL的ROP的适度控制，并成功生产了分子量可变且分子量分布相对较窄的PEG-b-PγBL双嵌段共聚物。仔细研究了催化体系，活化温度和单体浓度对PEG-b-PγBL的γBL转化率和分子量的影响。还研究了所得PEG-b-PγBL的热性质和相行为。另一方面，氢化钠用于活化PEG的羟基以形成醇钠，作为γBLROP的引发体系。两种催化/引发体系均显示出对γBL的ROP的适度控制，并成功生产了分子量可变且分子量分布相对较窄的PEG-b-PγBL双嵌段共聚物。仔细研究了催化体系，活化温度和单体浓度对PEG-b-PγBL的γBL转化率和分子量的影响。还研究了所得PEG-b-PγBL的热性质和相行为。两种催化/引发体系均显示出对γBL的ROP的适度控制，并成功生产了分子量可变且分子量分布相对较窄的PEG-b-PγBL双嵌段共聚物。仔细研究了催化体系，活化温度和单体浓度对PEG-b-PγBL的γBL转化率和分子量的影响。还研究了所得PEG-b-PγBL的热性质和相行为。两种催化/引发体系均显示出对γBL的ROP的适度控制，并成功生产了分子量可变且分子量分布相对较窄的PEG-b-PγBL双嵌段共聚物。仔细研究了催化体系，活化温度和单体浓度对PEG-b-PγBL的γBL转化率和分子量的影响。还研究了所得PEG-b-PγBL的热性质和相行为。