Synthesis and thermal stability of α, ω-hydroxy-terminated phenyl/phenylene-containing polysiloxanes with high vinyl content

doi:10.11949/0438-1157.20241144

Abstract

Abstract:

Silicone rubbers are widely used in many fields due to their excellent performance, but they are prone to degradation in high temperature. In this paper, vinyl-containing polysiloxanes with phenyl (P1) and phenylene (P2) were synthesized via anionic ring-opening and condensation polymerization using tetramethylammonium silanolate (TMAS) as catalyst, deionized water as capping agent, and octamethylcyclotetrasiloxane (D₄), 1,3,5,7-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane (D₄Vi), and octaphenylcyclotetrasiloxane (D₄Ph₂) or 1,4-bis(dimethylhydroxysilyl)benzene (BHB) as monomers. The effect of reaction temperature, time and the dosages of catalyst and capping agent were investigated. Their structure was studied by spectroscopic characterization techniques including FTIR, ¹H, ¹³C, and ²⁹Si NMR, and Raman spectroscopy. The effects of vinyl and phenylene on the mechanical properties and thermal stability of cured polysiloxanes were studied. The results showed that the introduction of vinyl and phenylene significantly increased the carbon residue rate of the polymer, which is due to the cross-linking reaction of vinyl and the branching reaction of phenylene at high temperatures. In addition, compared with P1, P2 with a high vinyl content has a higher initial decomposition temperature and better resistance to hot air aging.

Key words: polysiloxane, high vinyl content, ring-opening polymerization, thermal stability

摘要：

硅橡胶因其优异的性能被广泛应用于许多领域，但在高温下容易发生降解。以四甲基氢氧化铵硅醇盐（TMAS）为催化剂，以八甲基环四硅氧烷（D₄）、1，3，5，7-四甲基-2，4，6，8-四乙烯基环四硅氧烷（D₄Vi）和八苯基环四硅氧烷（D₄Ph₂）或1，4-双（二甲基羟基硅基）苯（BHB）为单体，通过阴离子开环缩合聚合反应合成了含高乙烯基的苯基（P1）和亚苯基（P2）聚硅氧烷。研究了反应温度、时间以及催化剂和封端剂用量的影响。通过红外、核磁以及拉曼光谱等表征技术分析了其结构。研究了乙烯基和亚苯基对固化聚硅氧烷力学性能和热稳定性的影响。结果表明，乙烯基和亚苯基的引入显著提高了聚合物的残炭率，这是由于乙烯基在高温下发生了交联反应，而亚苯基在高温下发生了支化反应。此外，与P1相比，乙烯基含量高的P2具有更高的初始分解温度和更好的耐热空气老化性能。

关键词: 聚硅氧烷, 高乙烯基, 开环聚合, 热稳定性

CLC Number:

TQ 333.93

Ziyang LI, Peixin SHEN, Xiao'a ZHANG, Chengzhong WANG, Ling SHI, Junying ZHANG. Synthesis and thermal stability of α, ω-hydroxy-terminated phenyl/phenylene-containing polysiloxanes with high vinyl content[J]. CIESC Journal, 2025, 76(6): 3041-3052.

李子阳, 申沛鑫, 张孝阿, 王成忠, 史翎, 张军营. α， ω-端羟基苯基/亚苯基高乙烯基聚硅氧烷的合成及热稳定性[J]. 化工学报, 2025, 76(6): 3041-3052.

Figures/Tables 21

References 45

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序号	温度/℃	反应时间/h	产率/%	η(25℃)/(Pa·s)	M_n	PDI
1	90	—	—	—	—	—
2	100	3.5	62	8.9	21100	1.56
3	110	2	77	9.3	25300	1.64
4	120	0.5	90	10.0	27200	1.51

序号	温度/℃	反应时间/h	产率/%	η(25℃)/(Pa·s)	M_n	PDI
1	90	—	—	—	—	—
2	100	3.5	62	8.9	21100	1.56
3	110	2	77	9.3	25300	1.64
4	120	0.5	90	10.0	27200	1.51

序号	TMAS/g	H₂O/g	产率/%	η/(Pa·s)	M_n	PDI
1	0.45	0.25	78	13.6	37700	1.54
2	0.60	0.25	82	12.8	32600	1.66
3	0.75	0.25	89	10.7	25200	1.43
4	0.90	0.25	96	9.3	21400	1.51
5	0.75	0.10	95	14.4	48600	1.74
6	0.75	0.15	95	14.1	46500	1.36
7	0.75	0.20	94	12.6	31400	1.53

序号	TMAS/g	H₂O/g	产率/%	η/(Pa·s)	M_n	PDI
1	0.45	0.25	78	13.6	37700	1.54
2	0.60	0.25	82	12.8	32600	1.66
3	0.75	0.25	89	10.7	25200	1.43
4	0.90	0.25	96	9.3	21400	1.51
5	0.75	0.10	95	14.4	48600	1.74
6	0.75	0.15	95	14.1	46500	1.36
7	0.75	0.20	94	12.6	31400	1.53

序号	温度/℃	反应时间/h	产率/%	η/(Pa·s)	M_n	PDI
1	90	3	56	16.6	69800	1.46
2	100	3	76	17.9	77700	1.54
3	110	3	95	20.9	81200	1.66
4	120	3	94	17.2	75700	1.64
5	110	5	96	22.1	92100	1.57
6	110	8	94	23.8	100300	1.58
7	110	10	95	24.4	101500	1.54