Thermosetting Cyclic Olefin Terpolymers with High Optical Transparency and High Heat-Resistance via Thermo-Induced Benzocyclobutene Cross-Linking

doi:10.19894/j.issn.1000-0518.250258

Chinese Journal of Applied Chemistry ›› 2025, Vol. 42 ›› Issue (12): 1619-1628.DOI: 10.19894/j.issn.1000-0518.250258

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Thermosetting Cyclic Olefin Terpolymers with High Optical Transparency and High Heat-Resistance via Thermo-Induced Benzocyclobutene Cross-Linking

Jian ZHANG¹^,², Yi-Xin ZHANG¹, Lei CUI¹(), Zhong-Bao JIAN¹^,²()

^1.State Key Laboratory of Polymer Science and Technology，Changchun Institute of Applied Chemistry，Chinese Academy of Sciences，Changchun 130022，China
^2.School of Applied Chemistry and Engineering，University of Science and Technology of China，Hefei 230026，China

Received:2025-06-26 Accepted:2025-09-05 Published:2025-12-01 Online:2025-12-30
Contact: Lei CUI,Zhong-Bao JIAN
Supported by:
the National Key R&D Program of China(2022YFB3607400);the National Natural Science Foundation of China(U23B6011);the Key Research Program of the Chinese Academy of Sciences(ZDRW-CN-2023-1);the Youth Innovation Promotion Association Program of the Chinese Academy of Sciences(2023235);Jilin Provincial Science and Technology Department Program(20230101347JC)

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Abstract

Abstract:

Cyclic olefin copolymer （COC） is a typical optical plastic， but its inherent thermoplastic nature results in poor heat- and solvent-resistance. Cross-linking is a promising solution to these problems. Traditional cross-linking mainly focuses on cyclic olefin copolymers containing unsaturated double bonds， and adopts vulcanization cross-linking， peroxide cross-linking， and UV-initiated thiol-ene reaction cross-linking. However， these cross-linking methods have the problems of low cross-linking efficiency， the need for additional additives such as initiators， and the generation of small molecule by-products， which are not in line with the requirements of atom-economy. Based on the merits of benzocyclobutene （BCB）， This work proposes to introduce BCB units into COCs by coordination-insertion polymerization， and obtain thermosetting cyclic olefin terpolymers （COTs） via BCB self-initiating ［4+4］ cycloaddition reaction at 250 ℃ for 2 h， which enables efficient cross-linked network formation without requiring catalysts， initiators， or generating by-products， demonstrating exceptional operational simplicity and scalability for practical application. The obtained thermosetting COTs have high thermal stability， with 5% mass fraction weight loss temperatures （T_d，5%） between 428.3 and 433.0 ℃； More excellent heat-resistance， with significantly higher glass transition temperatures （T_g）； high optical transmittance （＞90%） and high Abbe number （49.9~54.0） and middle refractive indices （1.53~1.55）； and higher tensile strength （more than one time versus before cross-linking）. This work demonstrates the advancement of BCB chemistry in cross-linking method and lays the foundation of next-generation optical thermosets， which have potential applications in the field of aerospace， communication， solvent packaging.

Key words: Thermosetting resin, Cyclic olefin terpolymer： Benzocyclobutene, Coordination-insertion polymerization, High transparency and high heat-resistance

CLC Number:

O631

Jian ZHANG, Yi-Xin ZHANG, Lei CUI, Zhong-Bao JIAN. Thermosetting Cyclic Olefin Terpolymers with High Optical Transparency and High Heat-Resistance via Thermo-Induced Benzocyclobutene Cross-Linking[J]. Chinese Journal of Applied Chemistry, 2025, 42(12): 1619-1628.

Figures/Tables 6

References 45

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Entry	n（M1）/mmol	n（M2）/mmol	V（TIBA）/mL	Yield/g	Act. ^b （10⁶）	x（M1）/%	x（M2） ^c /%	Conv._M1^d /%	Conv._M2^d /%	10^-4·M_n^e	PDI ^e	T_m，T_g^f /℃
1	1	TCD （7.56）	5	0.95	1.1	2.6	22.8	39.6	45.9	2.3	1.8	-，107.7
2	1	TCD （7.56）	2.5	1.48	1.8	2.4	21.0	59.5	68.9	2.9	2.1	-，98.3
3	1	TCD （7.56）	1.75	1.74	2.1	2.2	17.6	69.7	73.8	5.4	1.9	n.d. ^j
4	1	TCD （7.56）	1	1.98	2.4	2.9	20.7	95.5	90.1	9.7	2.3	87.8，-
5	1	TCD （7.56）	0.1	Gel	/	/	/	/	/	/	/	/
6	1	TCD （12.5）	1	2.09	2.5	2.2	26.2	69.5	66.2	7.1	3.2	-，95.0
7 ^g	1	TCD （12.5）	1	2.50	1.5	2.1	25.9	80.0	78.9	9.1	3.4	n.d. ^j
8 ^h	1	TCD （12.5）	2	2.54	1.5	2.2	27.8	81.8	82.7	4.2	3.1	-，109.4
9 ^h	1	TCD （15.6）	2	3.20	1.9	2	30.6	89.2	87.5	4.9	4.3	-，122.4
10 ⁱ	1	TCD （12.5）	2	2.64	0.8	2.1	25.0	85.9	81.8	4.6	3.0	120.5，-
11 ⁱ	1	TCD （15.6）	2	3.16	1.0	2.2	24.7	100.0	77.9	7.3	3.0	119.8，-
12	1	NB （11.0）	1	1.74	2.1	1.9	26.7	68.0	86.2	15.0	1.3	n.d. ^j
13	1	NB （13.0）	1	1.89	2.3	1.9	30.1	70.3	85.7	11.8	1.6	-，74.8

Entry	n（M1）/mmol	n（M2）/mmol	V（TIBA）/mL	Yield/g	Act. ^b （10⁶）	x（M1）/%	x（M2） ^c /%	Conv._M1^d /%	Conv._M2^d /%	10^-4·M_n^e	PDI ^e	T_m，T_g^f /℃
1	1	TCD （7.56）	5	0.95	1.1	2.6	22.8	39.6	45.9	2.3	1.8	-，107.7
2	1	TCD （7.56）	2.5	1.48	1.8	2.4	21.0	59.5	68.9	2.9	2.1	-，98.3
3	1	TCD （7.56）	1.75	1.74	2.1	2.2	17.6	69.7	73.8	5.4	1.9	n.d. ^j
4	1	TCD （7.56）	1	1.98	2.4	2.9	20.7	95.5	90.1	9.7	2.3	87.8，-
5	1	TCD （7.56）	0.1	Gel	/	/	/	/	/	/	/	/
6	1	TCD （12.5）	1	2.09	2.5	2.2	26.2	69.5	66.2	7.1	3.2	-，95.0
7 ^g	1	TCD （12.5）	1	2.50	1.5	2.1	25.9	80.0	78.9	9.1	3.4	n.d. ^j
8 ^h	1	TCD （12.5）	2	2.54	1.5	2.2	27.8	81.8	82.7	4.2	3.1	-，109.4
9 ^h	1	TCD （15.6）	2	3.20	1.9	2	30.6	89.2	87.5	4.9	4.3	-，122.4
10 ⁱ	1	TCD （12.5）	2	2.64	0.8	2.1	25.0	85.9	81.8	4.6	3.0	120.5，-
11 ⁱ	1	TCD （15.6）	2	3.16	1.0	2.2	24.7	100.0	77.9	7.3	3.0	119.8，-
12	1	NB （11.0）	1	1.74	2.1	1.9	26.7	68.0	86.2	15.0	1.3	n.d. ^j
13	1	NB （13.0）	1	1.89	2.3	1.9	30.1	70.3	85.7	11.8	1.6	-，74.8

Entry	COT	Before cross-linking				After cross-linking
Entry	COT	n_D^b	n_F^c	n_C^d	v^e	n_D	n_F	n_C	v
1	x（M1）=2.9/%， x（TCD）=20.7/%	1.547 2	1.555 6	1.545 0	51.6	1.547 2	1.555 5	1.544 7	50.7
2	x（M1）=2.2/%， x（TCD）=26.2/%	1.553 9	1.560 0	1.550 6	58.9	1.549 2	1.557 0	1.546 0	49.9
3	x（M1）=2.1/%， x（TCD）=25.9/%	1.551 2	1.557 7	1.547 8	55.7	1.549 1	1.557 0	1.546 6	52.8
4	x（M1）=1.9/%， x（NB）=30.1/%	1.537 7	1.547 2	1.537 2	53.8	1.539 6	1.547 0	1.537 0	54.0

Entry	COT	Before cross-linking				After cross-linking
Entry	COT	n_D^b	n_F^c	n_C^d	v^e	n_D	n_F	n_C	v
1	x（M1）=2.9/%， x（TCD）=20.7/%	1.547 2	1.555 6	1.545 0	51.6	1.547 2	1.555 5	1.544 7	50.7
2	x（M1）=2.2/%， x（TCD）=26.2/%	1.553 9	1.560 0	1.550 6	58.9	1.549 2	1.557 0	1.546 0	49.9
3	x（M1）=2.1/%， x（TCD）=25.9/%	1.551 2	1.557 7	1.547 8	55.7	1.549 1	1.557 0	1.546 6	52.8
4	x（M1）=1.9/%， x（NB）=30.1/%	1.537 7	1.547 2	1.537 2	53.8	1.539 6	1.547 0	1.537 0	54.0

Thermosetting Cyclic Olefin Terpolymers with High Optical Transparency and High Heat-Resistance via Thermo-Induced Benzocyclobutene Cross-Linking

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