支化度和分子量对树枝化三嵌段共聚物熔融和结晶性能的影响

Effect of Generation and Molecule Weight on the Melting Point and Crystallization Properties of Dendritic Tri-block Copolymers

从PEG10000出发合成了一系列分子量相同而支化度不同和支化度相同而分子量不同的PCL-PEG-PCL树枝化三嵌段共聚物,采用DSC测定了共聚物的熔点及结晶温度。结果表明:在相同分子量下,随支化度的提高,熔点和结晶温度都向低温方向移动;在相同支化度下二者都随分子量的增大向高温方向移动。采用XRD观察了共聚物中不同组分的结晶情况,结果表明:在相同分子量下,支化度对PEG段的结晶有非常大的影响,当支化度G≥3时PEG段的结晶就完全被抑制了;在相同支化度(G=2)下,PCL段的聚合度对PEG段的结晶抑制作用也非常明显,当聚合度P_d≥22时,PEG段的结晶完全被抑制。

A series of dendritic tri-block copolymers with same molecule weight （Mw） and different generations （G） or different molecule weights and same generation were synthesized from PEG10000. DSC was performed to analyse the melting point and crystallization of copolymers. The results showed that with the same Mw, the melting point and crystallization temperature reduced upon increasing the generation, while increased upon increasing Mw with the same generation （G=2）. XRD was employed to analyse the crystallization of different blocks. The results showed that with the same Mw, generation influenced the PEG crystallization tremendously and the PEG crystallization was inhibited completely when G≥3. With the same generation （G=2）, the polymerization degree （Pet） of PCL arms inhibited the PEG crystallization obviously. When Pd≥22,PEG crystallization was inhibited completely.