以高顺式聚丁二烯为软段的三嵌段共聚物的制备

Preparation of Triblock Copolymers with High Cis-1,4-polybutadiene as Soft Segments

从高顺式端羟基聚丁二烯(HTPB)出发,分别以ε-己内酯和苯乙烯为单体合成了2类以高顺式聚丁二烯为软段的三嵌段共聚物.以高顺式HTPB为大分子引发剂、辛酸亚锡为催化剂,引发ε-己内酯的开环聚合,合成了聚己内酯-b-聚丁二烯-b-聚己内酯三嵌段共聚物(CLBCL);通过高顺式HTPB末端羟基与2-溴代异丁酰溴(BBi B)间的酯化反应制备了ATRP大分子引发剂(Bi B-PB-Bi B),进而引发苯乙烯进行电子转移活化再生催化剂原子转移自由基聚合(ARGET ATRP)反应,合成了聚苯乙烯-b-聚丁二烯-b-聚苯乙烯三嵌段共聚物(SBS),反应具有较好的可控性,产物分子量分布较窄.通过红外光谱(FTIR)、核磁共振氢谱(1H-NMR)和碳谱(13CNMR)、热重分析(TGA)和示差扫描量热分析(DSC)等对所制备共聚物的结构和性能进行了测试表征.TGA曲线表明,提高聚己内酯链段的含量,可在一定程度上提高CLBCL共聚物的热稳定性;SBS共聚物的热分解过程表现为一个阶段,与HTPB相比,其热稳定性略有提高.从CLBCL共聚物的DSC曲线上可明显观察到聚丁二烯链段的玻璃化转变温度和聚己内酯链段的熔点;SBS共聚物具有2个玻璃化转变温度,为–104.1和102.4oC,分别对应于聚丁二烯链段和聚苯乙烯链段的玻璃化转变温度.

Taking high cis-1,4 hydroxyl-terminated polybutadiene （HTPB） as a starting material, two kinds of triblock copolymers were successfully synthesized by polymerization of ε-caprolactone （ε-CL） and styrene. Polycaprolactone-b-polybutadiene-b-polycaprolactone triblock copolymer （CLBCL） was synthesized via the ring- opening polymerization of ε-CL with stannous octanoate [Sn（Oct）2] as the catalyst and HTPB as the macroinitiator. The length of PCL segments was controlled by changing the reaction time based on the living property of the ring- opening polymerization. Besides, the reaction between HTPB and 2-bromoisobutyryl bromide yielded the Atom Transfer Radical Polymerization （ATRP） macroinitiator （BiB-PB-BiB）, which was used for the preparation of the polystyrene-b-polybutadiene-b-polystyrenetriblock copolymers （SBS） via the Activators Regenerated by Electron Transfer for ATRP （ARGET ATRP） of styrene. The ARGET ATRP reaction was controllable and the molecular weight distribution of the copolymers was narrow. The structure of these triblock copolymers was characterized by Fourier transform infrared spectroscopy （FTIR）, nuclear magnetic resonance spectroscopy （^1H-NMR and ^13C-NMR）, gel permeation chromatography （GPC）, and their thermal properties were tested by thermo gravimetric analysis （TGA） and differential scanning calorimetry （DSC）. TGA analysis indicated that the thermal stability of the CLBCL triblock copolymers increased with the increase in PCL content in the copolymers. Only one thermal degradation stage was observed for the SBS triblock copolymers from the TGA curves and the thermal stability of copolymers was slightly better than HTPB precursors. In the DSC curves ofCLBCL copolymers, the glass transition temperature at -106.0 ℃ for the PB segments and the melting temperature at 54.4 ℃ for the PCL segments were detected. The results of DSC analysis for the SBS triblock copolymers indicated that there were two glass transition temperatures at -104.1 and 102.4 ℃, which corresponded to the PB and the PS segments, respectively.