高分子量立构复合结晶的三枝化PPO-PDLA-PLLA嵌段共聚物

doi:10.7503/cjcu20140301

摘要/Abstract

摘要：

以三枝化低不饱和度聚环氧丙烷(PPO)引发D-丙交酯(D-LA)逐步开环聚合, 合成了三枝化聚环氧丙烷-聚右旋乳酸(PPO-PDLA)共聚物. 用辛酸亚锡Sn(Oct)₂与PPO-PDLA端羟基反应进行Sn(Oct)封端, 制备了三枝化PPO-PDLA-Sn(Oct)预聚物. 再于130 ℃下, 以其作为大分子引发剂与L-丙交酯(L-LA)开环聚合, 合成了分子量>10⁵的三枝化PPO-PDLA-PLLA嵌段共聚物. 活性端基的引入, 降低了聚合反应温度, 从而降低了聚合中的酯交换或热降解反应发生的概率. 实现了高分子量PPO-PDLA-PLLA嵌段共聚物的合成. 结构测试结果表明, 合成的嵌段共聚物具有分子结构易控及立构规整度高等特点. 在结晶-熔融-再结晶重复热处理下, 三枝化PPO-PDLA-PLLA嵌段共聚物仅发生立构复合聚乳酸结晶, 且结晶能力稳定.

关键词: 封端, 开环聚合, 立构嵌段聚乳酸, 三枝化PPO-PDLA-PLLA嵌段共聚物, 立构复合结晶

Abstract:

Three-arm poly(propylene oxide)(PPO) was used as a macroinitiator for the ring-opening polymerization(ROP) of D-lactide to obtain three-arm poly(propylene oxide)-block-poly(D-lactic acid)(PPO-PDLA). PPO-PDLA copolymer was then reacted with stannous octoate [Sn(Oct)₂] to obtain Sn(Oct) end-capped PPO-PDLA[PPO-PDLA-Sn(Oct)]. The PPO-PDLA-Sn(Oct) can be used as an efficient macroinitiator for the ROP of L-lactide to synthesize three-arm PPO-PDLA-PLLA at 130 ℃, which reduces the occurrence of hydrolysis and transesterification reaction. PPO-PDLA-PLLA copolymers with high molecular weight were synthesized by this novel and simple method. The results show that the composite of PPO-PDLA-PLLA can be easily tuned by controlling the feed ratio of L-lactide and D-lactide, and the stereoregularity of PPO-PDLA-PLLA is high. Moreover, the stereocomplexes of PPO-PDLA-PLLA can survive melting to reform the stereo-complex crystallites.

Key words: End capping, Ring-open polymerization, Stereoblock poly(lactic acid), Three-arm PPO-PDLA-PLLA copolymer, Stereocomplex crystallite

中图分类号:

O631

TrendMD:

李伟, 马艳, 李远翔, 范仲勇. 高分子量立构复合结晶的三枝化PPO-PDLA-PLLA嵌段共聚物. 高等学校化学学报, 2014, 35(7): 1553.

LI Wei, MA Yan, LI Yuanxiang, FAN Zhongyong. Three-arm Stereocomplexed PPO-PDLA-PLLA Copolymer with High Molecular Weight^†. Chem. J. Chinese Universities, 2014, 35(7): 1553.

图/表 10

Table 1 Characterization of PD1-7 and PPO-PDLA-PLLA samples

Sample	Feed ratio of PO∶LA	Molar ratio of PO∶LA^*	10^-4 $M n *$	GPC		$α 58925$ / (deg·dm^-1·g^-1·cm³)	Content of D-LA(%)
Sample	Feed ratio of PO∶LA	Molar ratio of PO∶LA^*	10^-4 $M n *$	10^-4M_n		$α 58925$ / (deg·dm^-1·g^-1·cm³)	PDI
PD1-7	1∶7	1∶6.8	3.2	2.4	1.7	148.2	96.3
PDL1-7-7	1∶14	1∶16	6.2	2.1	1.8	-6.4	48.0
PDL1-7-14	1∶21	1∶25	9.6	4.1	2.6	-69.4	28.3
PDL1-7-28	1∶35	1∶43	14.0	5.8	2.8	-116.5	13.6

Table 1 Characterization of PD1-7 and PPO-PDLA-PLLA samples

Sample	Feed ratio of PO∶LA	Molar ratio of PO∶LA^*	10^-4 $M n *$	GPC		$α 58925$ / (deg·dm^-1·g^-1·cm³)	Content of D-LA(%)
Sample	Feed ratio of PO∶LA	Molar ratio of PO∶LA^*	10^-4 $M n *$	10^-4M_n		$α 58925$ / (deg·dm^-1·g^-1·cm³)	PDI
PD1-7	1∶7	1∶6.8	3.2	2.4	1.7	148.2	96.3
PDL1-7-7	1∶14	1∶16	6.2	2.1	1.8	-6.4	48.0
PDL1-7-14	1∶21	1∶25	9.6	4.1	2.6	-69.4	28.3
PDL1-7-28	1∶35	1∶43	14.0	5.8	2.8	-116.5	13.6

Fig.1 1H NMR spectra of PPO(A) and PPO-PDLA-Sn(Oct)(B)

Fig.2 FTIR spectra of PD1-7(A) and PDL1-7-7(B)

Fig.3 1H NMR spectra of PD1-7 and PPO-PDLA-PLLA

Fig.4 13C NMR spectra of PPO-PDLA-PLLA

Fig.5 DSC curves of PD1-7 and PPO-PDLA-PLLA samples after quenched from melting state

Table 2 DSC measurements of PD1-7 and PPO-PDLA-PLLA samples

Sample	T_g/℃	T_c/℃	T_m/℃	ΔH_m/(J·g^-1)	χ_c(%)
PD1-7	43.2	77.7	163.6	45.4	53.6
PDL1-7-7	45.8	83.8	191.3	37.5	27.9
PDL1-7-14	52.4	91.7	195.3	33.8	24.7
PDL1-7-28	55.7	97.0	196.5	22.5	16.2

Fig.6 DSC curves of PPO-PDLA-PLLA samples in heating run cycles

Table 3 Results obtained from DSC measurements of PPO-PDLA-PLLA recrystallization samples

Sample	Heating run cycles	T_g/℃	T_c/℃	ΔH_c/(J·g^-1)	T_m/℃	ΔH_m/(J·g^-1)
PDL1-7-7	1	43.3	81.9	-24.6	191.8	39.3
	2	42.9	81.1	-26.0	190.5	37.1
	3	42.8	81.2	-25.5	189.9	35.1
PDL1-7-14	1	49.4	90.6	-22.1	195.1	34.2
	2	50.7	90.5	-21.9	194.6	33.8
	3	50.7	90.7	-21.5	194.5	33.0
PDL1-7-28	1	54.1	95.6	-15.1	195.8	20.8
	2	53.6	96.1	-14.8	195.1	19.3
	3	53.7	96.5	-14.3	194.9	18.1

Fig.7 WAXD curves of PD1-7 and PPO-PDLA-PLLA samples

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