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合成了系列聚右旋乳酸(PDLA)嵌段重量分率(fw=0～0.61)的窄分子量分布聚苯乙烯-b-聚右旋乳酸二嵌段共聚物(PS-b-PDLA).运用温度调制示差扫描热分析仪(TMDSC)和热台偏振光显微镜(POM)等研究手段,对制备所得的结晶性二嵌段共聚物的热性能、结晶速率与结晶形貌等进行了研究.研究结果表明,与聚右旋乳酸均聚物相比,随着PS-b-PDLA中结晶性PDLA嵌段重量分率fw减少,无定形聚苯乙烯嵌段(PS)对PDLA嵌段链段的结晶抑制作用增强,PS-b-PDLA的热结晶性能与结晶形貌发生显著变化;相对于PDLA均聚物,PS-b-PDLA的冷结晶温度(Tcc)和结晶平衡熔点(Tm0)分别下降14℃和38℃,球晶生长速率明显降低.在无定形PS嵌段链段的玻璃化温度(Tg)附近,二嵌段PS-b-PDLA的结晶行为出现拐点,揭示PS嵌段由于相分离所形成纳米微相空间对PS-b-PDLA中PDLA链段的结晶产生影响,并且该影响作用程度与PDLA嵌段的重量分率fw和结晶温度(Tc)相关。
A series of narrow molecular weight distribution polystyrene-b-poly-D-lactic acid diblock copolymers (PS-b-PDLA) with a series of PDLA block weight fractions (fw = 0 ~ 0.61) Temperature modulation differential scanning calorimeter (TMDSC) and hot stage polarization microscope (POM) were used to study the thermal properties, crystallization rate and crystalline morphology of the prepared crystalline diblock copolymer. The results show that, as the crystalline PDLA block weight fraction fw decreases in PS-b-PDLA as compared to poly-lactic acid homopolymer, amorphous polystyrene block (PS) The crystallization inhibition and crystallization of PS-b-PDLA significantly changed. Compared with PDLA homopolymer, the cold crystallization temperature (Tcc) and crystallization equilibrium melting point (Tm0) of PS-b-PDLA decreased The spherulitic growth rate decreased obviously at 14 ℃ and 38 ℃ .The crystallization behavior of diblock PS-b-PDLA showed an inflection point near the glass transition temperature (Tg) of the amorphous PS block, revealing that the PS block due to the phase The separation of the formed nano-micro-phase space affects the crystallization of the PDLA segment in PS-b-PDLA, and the degree of influence is related to the weight fraction of the PDLA block, fw And crystallization temperature (Tc).