Progress in dynamically crosslinked polyolefins derived from ring-opening metathesis polymerization

doi:10.11949/0438-1157.20231396

Abstract

Abstract:

Ring-opening metathesis polymerization (ROMP) provides a precise and efficient way to prepare polyolefins, which enables the preparation of functional polymer materials with different topological structures. Although thermoplastic olefin polymers can be melted and reprocessed at high temperatures, their low mechanical properties and heat resistance limit their service life under extreme conditions. In general, the thermomechanical properties of polyolefin materials can be greatly improved by crosslinking modification, but it also brings difficulties to the recycling of waste materials. To address above limitations, fabricating dynamically crosslinked polyolefins with dynamic bonds has attracted extensive attentions. These polymers enhance mechanical properties while retaining the ability to be reprocessed. This review article focuses on the recent progress of polyolefins that are synthesized via ring-opening metathesis polymerization and followed by dynamically crosslinking modification. Finally, the development status and future research of this field are summarized.

Key words: polyolefins, ring-opening metathesis polymerization, dynamic crosslinking, reversible crosslinking, self-healing, reprocessable

摘要：

开环易位聚合（ROMP）为烯烃聚合物的制备提供了一种精确而高效的方法，可制备不同拓扑结构的功能性热塑性烯烃聚合物材料。热塑性烯烃聚合物尽管可以在高温下熔融再加工，但其较低的力学性能和耐热性能限制了其在极端条件下的使用寿命。通过固化交联改性则可以大大改善材料的力学性能等，但也为废旧材料的回收再利用带来了困难。为克服上述局限，构建含有动态键的烯烃聚合物交联网络引起了广泛关注，该类聚合物在提升力学等性能的同时也赋予了其可重复加工的能力。本文聚焦于通过开环易位聚合合成不同拓扑结构的烯烃聚合物，并利用不同类型动态键对其进行动态交联改性的最新研究进展。并对该领域的发展现状和未来研究方向进行了总结。

关键词: 烯烃聚合物, 开环易位聚合, 动态交联, 可逆交联, 自修复, 重加工

CLC Number:

TQ 028.8

Lisheng WU, Jie LIU, Tiantian WANG, Zhenghong LUO, Yinning ZHOU. Progress in dynamically crosslinked polyolefins derived from ring-opening metathesis polymerization[J]. CIESC Journal, 2024, 75(4): 1118-1136.

吴立盛, 刘杰, 王添添, 罗正鸿, 周寅宁. 开环易位烯烃聚合物的动态交联改性研究进展[J]. 化工学报, 2024, 75(4): 1118-1136.

Figures/Tables 10

Fig.1 Schematic representation of ROMP of cyclopentene and norbornene, and Grubbs catalysts

Fig.2 Synthetic pathways and properties of polyolefins dynamically crosslinked by hydrogen bonded[20, 62-63]: (a) six-point and three-point hydrogen bonded complexes; (b) reversible energy dissipative rupture of sacrificial hydrogen bonds in a G2-mediated self-healing olefin-containing network; (c) synthesis of the amid-containing CO network (ACON) and hydrogen-bond-blocked control network (BACON); (d) ABA type block cyclic olefin copolymer （A block: 2-ureido-4[1H]-pyrimidinone (UPy)-functionalized norbornene homopolymer； B block: 2-ureido-4[1H]-pyrimidinone (UPy)-functionalized norbornene random copolymer）; (e) schematic graph for energy dissipative rupture of polymer network

Fig.3 Synthetic pathways and properties of cyclic olefin polymer dynamically crosslinked by ionic interaction[67-69]: (a) imidazolium-based norbornene copolymer with different counterions; (b) photographs showing the self-healing properties of samples and its mechanism under the testing process; (c) chemical structures of gradient copolymers and the mechanism for elastic response; (d) synthetic route of the imidazolium-based norbornene copolymers with different spacer and tail lengths

Fig.4 Synthetic pathways and properties of cyclic olefin polymer dynamically crosslinked by host-guest interaction[70]: (a) supramolecular polymers; (b) covalent polymers; (c) synergistic covalent and supramolecular polymers; (d) comparison of mechanical and dynamic properties of three polymers above

Fig.5 Synthetic pathways and properties of cyclic olefin polymer dynamically crosslinked by dual-molecular interaction[72]: (a) synthetic route of dual-cross-linked polymer; (b) schematic graph of dense UPy region limited deformation, while UPy dimers in sparse regions with weak ionic interaction can act as sacrificial bonds for energy dissipation; (c) schematic illustration of the NIR triggered healing process

Fig.6 Synthetic pathways and properties of polyolefin dynamically crosslinked by olefin metathesis[73]: (a) schematic of the depolymerization-repolymerization cycle of network polymers based on ROMP; (b) depolymerization temperatures of copolymers depending on the ratios of two comonomers; (c) the storage modulus of sample which were first initiated at 55℃ and cycled between 25℃ and 55℃

Fig.7 Synthetic pathways and properties of polyolefins dynamically crosslinked by boronic ester[74-75]: (a) tuning neighboring group to control the exchange kinetics of boronic ester; (b) dynamic exchange of boronic ester crosslinkers affords olefin polymer; (c) synthesis of a DCNA based on the PE backbone; (d) creep tests of PE with different mass fractions of PE-AB; (e) schematic representation of dynamic covalent networks with reprocessability

Fig.8 Synthetic pathways and properties of cyclic olefin polymer dynamically crosslinked by ester bond and siloxane bond[22, 76]: (a) synthetic scheme for generating dynamic bottlebrush polymer networks that undergo transesterification; (b) preparation of polydicyclopentadiene (pDCPD) with bifunctional silyl ether; (c) stress relaxation curves of EtSi7 and pDCPD copolymer cured with and without octanoic acid; (d) stress-relaxation curves of iPrSi7 and pDCPD copolymer cured with and without octanoic acid; (e) Arrhenius plots of stress relaxation for these two samples

Fig.9 Synthetic pathways and properties of polyolefin dynamically crosslinked by vinylogous urethane bond[77]: (a) telechelic polymers by ROMP of COE in the presence of CTA bearing acetoacetate groups; (b) synthesis of dynamic crosslinked network using telechelic polymer and TREN

Fig.10 Synthetic pathways and properties of cyclic olefin polymer dynamically crosslinked by dual-dynamic covalent bonds[78]: (a) synthetic scheme for the network crosslinked by dual-dynamic covalent bonds; (b) schematic illustration of the two independently controllable topological transformations; (c) transesterification between hydroxyl groups and polycaprolactone side chains; (d) DSC curves for the isomerized materials obtained with different UV irradiation time; (e) stress-strain curves of the isomerized materials

References 85

1	Bielawski C W, Grubbs R H. Living ring-opening metathesis polymerization[J]. Progress in Polymer Science, 2007, 32(1): 1-29.
2	Slugovc C. The ring opening metathesis polymerisation toolbox[J]. Macromolecular Rapid Communications, 2004, 25(14): 1283-1297.
3	So L C, Faucher S, Zhu S P. Synthesis of low molecular weight polyethylenes and polyethylene mimics with controlled chain structures[J]. Progress in Polymer Science, 2014, 39(6): 1196-1234.
4	Truett W L, Johnson D R, Robinson I M, et al. Polynorbornene by coordination polymerization[J]. Journal of the American Chemical Society, 1960, 82(9): 2337-2340.
5	Jean-Louis Hérisson P, Chauvin Y. Catalyse de transformation des oléfines par les complexes du tungstène. Ⅱ. Télomérisation des oléfines cycliques en présence d'oléfines acycliques[J]. Die Makromolekulare Chemie, 1971, 141(1): 161-176.
6	Schrock R. Recent advances in olefin metathesis by molybdenum and tungsten imido alkylidene complexes[J]. Journal of Molecular Catalysis A: Chemical, 2004, 213(1): 21-30.
7	Choi T L, Grubbs R H. Controlled living ring-opening-metathesis polymerization by a fast-initiating ruthenium catalyst[J]. Angewandte Chemie International Edition, 2003, 42(15): 1743-1746.
8	Jeong H, Kozera D J, Schrock R R, et al. Z-selective ring-opening metathesis polymerization of 3-substituted cyclooctenes by monoaryloxide pyrrolide imido alkylidene (MAP) catalysts of molybdenum and tungsten[J]. Organometallics, 2013, 32(17): 4843-4850.
9	Rosebrugh L E, Marx V M, Keitz B K, et al. Synthesis of highly cis, syndiotactic polymers via ring-opening metathesis polymerization using ruthenium metathesis catalysts[J]. Journal of the American Chemical Society, 2013, 135(27): 10032-10035.
10	Schrock R R. Synthesis of stereoregular polymers through ring-opening metathesis polymerization[J]. Accounts of Chemical Research, 2014, 47(8): 2457-2466.
11	Yasir M, Liu P, Tennie I K, et al. Catalytic living ring-opening metathesis polymerization with Grubbs' second- and third-generation catalysts[J]. Nature Chemistry, 2019, 11: 488-494.
12	Hyatt M G, Walsh D J, Lord R L, et al. Mechanistic and kinetic studies of the ring opening metathesis polymerization of norbornenyl monomers by a Grubbs third generation catalyst[J]. Journal of the American Chemical Society, 2019, 141(44): 17918-17925.
13	Blosch S E, Alaboalirat M, Eades C B, et al. Solvent effects in grafting-through ring-opening metathesis polymerization[J]. Macromolecules, 2022, 55(9): 3522-3532.
14	Wang T T, Shi Y J, Li S, et al. Unraveling the compounded interplay of weakly and strongly coordinating ligands in G3-catalyzed living metathesis polymerization: toward well-defined polynorbornene at ambient temperature[J]. Macromolecules, 2023, 56(18): 7379-7388.
15	姜啟亮, 陈琦, 姜付本, 等. 降冰片烯及其衍生物开环易位聚合的研究进展[J]. 材料导报, 2018, 32(7): 1165-1173.
	Jiang Q L, Chen Q, Jiang F B, et al. A review of the ring-opening metathesis polymerization involving norbornene or its derivatives[J]. Materials Review, 2018, 32(7): 1165-1173.
16	Morita T, Maughon B R, Bielawski C W, et al. A ring-opening metathesis polymerization (ROMP) approach to carboxyl- and amino-terminated telechelic poly(butadiene)s[J]. Macromolecules, 2000, 33(17): 6621-6623.
17	Pitet L M, Hillmyer M A. Carboxy-telechelic polyolefins by ROMP using maleic acid as a chain transfer agent[J]. Macromolecules, 2011, 44(7): 2378-2381.
18	Nomura K, Abdellatif M M. Precise synthesis of polymers containing functional end groups by living ring-opening metathesis polymerization (ROMP): efficient tools for synthesis of block/graft copolymers[J]. Polymer, 2010, 51(9): 1861-1881.
19	Yang J X, Long Y Y, Pan L, et al. Spontaneously healable thermoplastic elastomers achieved through one-pot living ring-opening metathesis copolymerization of well-designed bulky monomers[J]. ACS Applied Materials & Interfaces, 2016, 8(19): 12445-12455.
20	Yoshida S, Ejima H, Yoshie N. Tough elastomers with superior self-recoverability induced by bioinspired multiphase design[J]. Advanced Functional Materials, 2017, 27(30): 1701670.
21	Allen M J, Wangkanont K, Raines R T, et al. ROMP from ROMP: a new approach to graft copolymer synthesis[J]. Macromolecules, 2009, 42(12): 4023-4027.
22	Self J L, Sample C S, Levi A E, et al. Dynamic bottlebrush polymer networks: self-healing in super-soft materials[J]. Journal of the American Chemical Society, 2020, 142(16): 7567-7573.
23	Varlas S, Hua Z, Jones J R, et al. Complementary nucleobase interactions drive the hierarchical self-assembly of core–shell bottlebrush block copolymers toward cylindrical supramolecules[J]. Macromolecules, 2020, 53(22): 9747-9757.
24	Fan J K, Ren N, Zhang C Y, et al. Synthesis of hyperbranched polyolefin with well-defined terminal functional group[J]. Polymer, 2022, 242: 124571.
25	Rylski A K, Cater H L, Mason K S, et al. Polymeric multimaterials by photochemical patterning of crystallinity[J]. Science, 2022, 378(6616): 211-215.
26	Zhao Y C, Rettner E M, Harry K L, et al. Chemically recyclable polyolefin-like multiblock polymers[J]. Science, 2023, 382(6668): 310-314.
27	Shim J S, Browne A W, Ahn C H. An on-chip whole blood/plasma separator with bead-packed microchannel on COC polymer[J]. Biomedical Microdevices, 2010, 12(5): 949-957.
28	Baek C, Kim J, Lee Y, et al. Fabrication and evaluation of cyclic olefin copolymer based implantable neural electrode[J]. IEEE Transactions on Bio-Medical Engineering, 2020, 67(9): 2542-2551.
29	Yamazaki M. Industrialization and application development of cyclo-olefin polymer[J]. Journal of Molecular Catalysis A: Chemical, 2004, 213(1): 81-87.
30	Zhang R, Madhavi V, Shaffer T D, et al. Cyclic olefin copolymers (COC)—excellent glass formers with low dynamic fragility[J]. Macromolecular Chemistry and Physics, 2022, 223(15): 2200065.
31	Zhao Y H, Zhang Y X, Cui L, et al. Cyclic olefin terpolymers with high refractive index and high optical transparency[J]. ACS Macro Letters, 2023, 12(3): 395-400.
32	Liu S C, Fan Y Q, Gao K X, et al. Fabrication of cyclo-olefin polymer-based microfluidic devices using CO₂ laser ablation[J]. Materials Research Express, 2018, 5(9): 095305.
33	Abdulrahman A, Waqas W, Nahla A, et al. A review of cyclic olefin copolymer applications in microfluidics and microdevices[J]. Macromolecular Materials and Engineering, 2022, 307(8): 2200053.
34	Stagnaro P, Mancini G, Piccinini A, et al. Novel ethylene/norbornene copolymers as nonreleasing antioxidants for food-contact polyolefinic materials[J]. Journal of Polymer Science B Polymer Physics, 2013, 51(13): 1007-1016.
35	Losio S, Tritto I, Boggioni L, et al. Fully consistent terpolymeric non-releasing antioxidant additives for long lasting polyolefin packaging materials[J]. Polymer Degradation and Stability, 2017, 144: 167-175.
36	Janjua S, Hussain Z, Khan Z, et al. Biopolymer blended films of poly(butylene succinate)/cyclic olefin copolymer with enhanced mechanical strength for packaging applications[J]. Journal of Applied Polymer Science, 2021, 138(12): 50081.
37	Sabzekar M, Pourafshari Chenar M, Maghsoud Z, et al. Cyclic olefin polymer as a novel membrane material for membrane distillation applications[J]. Journal of Membrane Science, 2021, 621: 118845.
38	赵阳, 李雪, 冯志明, 等. 降冰片烯类聚合物用于离子交换膜的研究进展[J]. 化工学报, 2015, 66(S1): 10-16.
	Zhao Y, Li X, Feng Z M, et al. Progress of ion exchange membrane based on poly(norbornene)s derivatives via ring-opening metathesis polymerization[J]. CIESC Journal, 2015, 66(S1): 10-16.
39	Kushner A M, Gabuchian V, Johnson E G, et al. Biomimetic design of reversibly unfolding cross-linker to enhance mechanical properties of 3D network polymers[J]. Journal of the American Chemical Society, 2007, 129(46): 14110-14111.
40	Luo F, Sun T L, Nakajima T, et al. Oppositely charged polyelectrolytes form tough, self-healing, and rebuildable hydrogels[J]. Advanced Materials, 2015, 27(17): 2722-2727.
41	Kean Z S, Hawk J L, Lin S T, et al. Increasing the maximum achievable strain of a covalent polymer gel through the addition of mechanically invisible cross-links[J]. Advanced Materials, 2014, 26(34): 6013-6018.
42	Liu J, Tan C S Y, Yu Z Y, et al. Biomimetic supramolecular polymer networks exhibiting both toughness and self-recovery[J]. Advanced Materials, 2017, 29(10): 1604951.
43	Lu Y X, Tournilhac F, Leibler L, et al. Making insoluble polymer networks malleable via olefin metathesis[J]. Journal of the American Chemical Society, 2012, 134(20): 8424-8427.
44	Lu Y X, Guan Z B. Olefin metathesis for effective polymer healing via dynamic exchange of strong carbon-carbon double bonds[J]. Journal of the American Chemical Society, 2012, 134(34): 14226-14231.
45	Montarnal D, Capelot M, Tournilhac F, et al. Silica-like malleable materials from permanent organic networks[J]. Science, 2011, 334(6058): 965-968.
46	Röttger M, Domenech T, van der Weegen R, et al. High-performance vitrimers from commodity thermoplastics through dioxaborolane metathesis[J]. Science, 2017, 356(6333): 62-65.
47	陈峰, 候宇坤, 赵骞. 一种硼酸酯动态交联环氧树脂的合成与性能[J]. 化工学报, 2019, 70(11): 4449-4456.
	Chen F, Hou Y K, Zhao Q. Synthesis and properties of epoxy resin crosslinked by dynamic boronic ester bonds[J]. CIESC Journal, 2019, 70(11): 4449-4456.
48	Guerre M, Taplan C, Nicolaÿ R, et al. Fluorinated vitrimer elastomers with a dual temperature response[J]. Journal of the American Chemical Society, 2018, 140(41): 13272-13284.
49	刘杰, 吴立盛, 李锦锦, 等. 含乙烯基胺酯键聚醚类可逆交联聚合物的制备及性能研究[J]. 化工学报, 2023, 47(7): 3051-3057.
	Liu J, Wu L S, Li J J, et al. Preparation and properties of polyether-based vinylogous urethane reversible crosslinked polymers[J]. CIESC Journal, 2023, 47(7): 3051-3057.
50	Nishimura Y, Chung J, Muradyan H, et al. Silyl ether as a robust and thermally stable dynamic covalent motif for malleable polymer design[J]. Journal of the American Chemical Society, 2017, 139(42): 14881-14884.
51	Wang A H, Niu H, He Z K, et al. Thermoreversible cross-linking of ethylene/propylene copolymer rubbers[J]. Polymer Chemistry, 2017, 8(31): 4494-4502.
52	Kar G P, Saed M O, Terentjev E M. Scalable upcycling of thermoplastic polyolefins into vitrimers through transesterification[J]. Journal of Materials Chemistry A, 2020, 8(45): 24137-24147.
53	Yang Y X, Huang L Y, Wu R Y, et al. Assembling of reprocessable polybutadiene-based vitrimers with high strength and shape memory via catalyst-free imine-coordinated boroxine[J]. ACS Applied Materials & Interfaces, 2020, 12(29): 33305-33314.
54	Liu S H, Liu X Y, He Z K, et al. Thermoreversible cross-linking of ethylene/propylene copolymers based on Diels-Alder chemistry: the cross-linking reaction kinetics[J]. Polymer Chemistry, 2020, 11(36): 5851-5860.
55	Maaz M, Riba-Bremerch A, Guibert C, et al. Synthesis of polyethylene vitrimers in a single step: consequences of graft structure, reactive extrusion conditions, and processing aids[J]. Macromolecules, 2021, 54(5): 2213-2225.
56	He Z K, Niu H, Liu L Y, et al. Elastomeric polyolefin vitrimer: dynamic imine bond cross-linked ethylene/propylene copolymer[J]. Polymer, 2021, 229: 124015.
57	Ahmadi M, Hanifpour A, Ghiassinejad S, et al. Polyolefins vitrimers: design principles and applications[J]. Chemistry of Materials, 2022, 34(23): 10249-10271.
58	Wang S J, Wang L, Wang B, et al. Facile preparation of recyclable cyclic polyolefin/polystyrene vitrimers with low dielectric loss based on semi-interpenetrating polymer networks for high-frequency copper-clad laminates[J]. Polymer, 2021, 233: 124214.
59	Xiao Y K, Liu P W, Wang W J, et al. Dynamically cross-linked polyolefin elastomers with highly improved mechanical and thermal performance[J]. Macromolecules, 2021, 54(22): 10381-10387.
60	Saed M O, Lin X Y, Terentjev E M. Dynamic semicrystalline networks of polypropylene with thiol-anhydride exchangeable crosslinks[J]. ACS Applied Materials & Interfaces, 2021, 13(35): 42044-42051.
61	Leone G, Palucci B, Zanchin G, et al. Dynamically cross-linked polyolefins via hydrogen bonds: tough yet soft thermoplastic elastomers with high elastic recovery[J]. ACS Applied Polymer Materials, 2022, 4(5): 3770-3778.
62	Nair K P, Breedveld V, Weck M. Complementary hydrogen-bonded thermoreversible polymer networks with tunable properties[J]. Macromolecules, 2008, 41(10): 3429-3438.
63	Neal J A, Mozhdehi D, Guan Z B. Enhancing mechanical performance of a covalent self-healing material by sacrificial noncovalent bonds[J]. Journal of the American Chemical Society, 2015, 137(14): 4846-4850.
64	Kang J, Son D, Wang G J N, et al. Tough and water-insensitive self-healing elastomer for robust electronic skin[J]. Advanced Materials, 2018, 30(13): 1706846.
65	Qin B, Zhang S, Sun P, et al. Tough and multi-recyclable cross-linked supramolecular polyureas via incorporating noncovalent bonds into main-chains[J]. Advanced Materials, 2020, 32(36): e2000096.
66	Chen L Y, You W, Wang J, et al. Enhancing the toughness and strength of polymers using mechanically interlocked hydrogen bonds[J]. Journal of the American Chemical Society, 2024, 146(1): 1109-1121.
67	Cui J, Nie F M, Yang J X, et al. Novel imidazolium-based poly(ionic liquid)s with different counterions for self-healing[J]. Journal of Materials Chemistry A, 2017, 5(48): 25220-25229.
68	Cui J, Ma Z, Pan L, et al. Self-healable gradient copolymers[J]. Materials Chemistry Frontiers, 2019, 3(3): 464-471.
69	Nie F M, Cui J, Zhou Y F, et al. Molecular-level tuning toward aggregation dynamics of self-healing materials[J]. Macromolecules, 2019, 52(14): 5289-5297.
70	Zhang Z M, Cheng L, Zhao J, et al. Synergistic covalent and supramolecular polymers for mechanically robust but dynamic materials[J]. Angewandte Chemie International Edition, 2020, 59(29): 12139-12146.
71	Deng J X, Bai R X, Zhao J, et al. Insights into the correlation of cross-linking modes with mechanical properties for dynamic polymeric networks[J]. Angewandte Chemie International Edition, 2023, 62(37): e202309058.
72	Nie F M, An C H, Cao D F, et al. Ru(Ⅱ) catalyst enables dynamic dual-cross-linked elastomers with near-infrared self-healing toward flexible electronics[J]. Advanced Functional Materials, 2022, 32(15): 2110616.
73	Liu H Y, Nelson A Z, Ren Y, et al. Dynamic remodeling of covalent networks via ring-opening metathesis polymerization[J]. ACS Macro Letters, 2018, 7(8): 933-937.
74	Cromwell O R, Chung J, Guan Z B. Malleable and self-healing covalent polymer networks through tunable dynamic boronic ester bonds[J]. Journal of the American Chemical Society, 2015, 137(20): 6492-6495.
75	Wang Z T, Gu Y, Ma M Y, et al. Strengthening polyethylene thermoplastics through a dynamic covalent networking additive based on alkylboron chemistry[J]. Macromolecules, 2021, 54(4): 1760-1766.
76	Husted K E L, Brown C M, Shieh P, et al. Remolding and deconstruction of industrial thermosets via carboxylic acid-catalyzed bifunctional silyl ether exchange[J]. Journal of the American Chemical Society, 2023, 145(3): 1916-1923.
77	Zheng S Q, Liu Y, Si G F, et al. Covalently crosslinked networks from telechelic polycyclooctene with reinforced properties[J]. Chinese Journal of Chemistry, 2023, 41(16): 2002-2009.
78	Miao W S, Yang B, Jin B J, et al. An orthogonal dynamic covalent polymer network with distinctive topology transformations for shape-and molecular architecture reconfiguration[J]. Angewandte Chemie, 2022, 134(11): e202109941.
79	Schlögl S, Trutschel M L, Chassé W, et al. Entanglement effects in elastomers: macroscopic vs microscopic properties[J]. Macromolecules, 2014, 47(9): 2759-2773.
80	Zhou H X, Schön E M, Wang M Z, et al. Crossover experiments applied to network formation reactions: improved strategies for counting elastically inactive molecular defects in PEG gels and hyperbranched polymers[J]. Journal of the American Chemical Society, 2014, 136(26): 9464-9470.
81	Wang J P, Lin T S, Gu Y W, et al. Counting secondary loops is required for accurate prediction of end-linked polymer network elasticity[J]. ACS Macro Letters, 2018, 7(2): 244-249.
82	Miyaji K, Sugiyama T, Ohashi T, et al. Study on homogeneity in sulfur cross-linked network structures of isoprene rubber by TD-NMR and AFM–zinc stearate system[J]. Macromolecules, 2020, 53(19): 8438-8449.
83	Wang R, Johnson J A, Olsen B D. Odd–even effect of junction functionality on the topology and elasticity of polymer networks[J]. Macromolecules, 2017, 50(6): 2556-2564.
84	De Keer L, Kilic K I, Van Steenberge P H M, et al. Computational prediction of the molecular configuration of three-dimensional network polymers[J]. Nature Materials, 2021, 20: 1422-1430.
85	Zhang K Y, Sun Y G, Yang H, et al. Investigations on thermomechanical and structure properties of pure and wet polyimine networks by molecular dynamics simulations[J]. Materials Today Communications, 2023, 36: 106758.

[1]	Wentao WU, Liangyong CHU, Lingjie ZHANG, Weimin TAN, Liming SHEN, Ningzhong BAO. High-efficient preparation of cardanol-based self-healing microcapsules [J]. CIESC Journal, 2023, 74(7): 3103-3115.
[2]	NI Zhuo, LIN Yuhao, HUANG Weiying, LIN Lirong. Preparation and reaction kinetics of epoxy resin microcapsules [J]. CIESC Journal, 2018, 69(4): 1790-1798.
[3]	YANG Qin, ZHAO Na, FANG Chunjuan, ZHAO Junkai, WANG Wendong. Preparation and mechanical properties of novel (C₃H₅O)₁CB[7]/PAA hydrogel with high elasticity and self-healing properties [J]. CIESC Journal, 2018, 69(12): 5326-5331.
[4]	FENG Lei, ZHAO Yubin, XIE Xiaofeng, LV Yafei. Preparation of tunable quaternary ammonium functionalized norbornene derivatives anion exchange membrane [J]. CIESC Journal, 2015, 66(S2): 257-262.
[5]	ZHAO Yang, LI Xue, FENG Zhiming, ZHAO Yubin, XIE Xiaofeng, CHAI Chunpeng, LUO Yunjun. Progress of ion exchange membrane based on poly(norbornene)s derivatives via ring-opening metathesis polymerization [J]. , 2015, 66(S1): 10-16.
[6]	LI Haiyan，ZHANG Libing，LI Jie，WANG Jun. Research progresses in extrinsic self-healing polymer materials [J]. Chemical Industry and Engineering Progree, 2014, 33(01): 133-139.
[7]	ZHANG Yunfei，DENG Guohua. Self-healing polymer gels based on dynamic covalent bonds [J]. Chemical Industry and Engineering Progree, 2012, 31(10): 2239-3344.
[8]	LI Haiyan，ZHANG Libing，WANG Jun. Research progresses in intrinsic self-healing polymer materials [J]. Chemical Industry and Engineering Progree, 2012, 31(07): 1549-1554.
[9]	ZHANG Xin，MENG Weijuan，WANG Chao，LU Zhanxia，ZHANG Yuehong，WANG Jian. Analysis of oligomers from polyolefins [J]. , 2009, 28(9): 1620-.