高不饱和丁基橡胶/氧化石墨烯复合材料的设计与制备
Design and Preparation of Highly Unsaturated Butyl Rubber/Graphene Oxide Composites
ABSTRACT
High-barrier rubber composites hold significant application potential in food packaging, pharmaceutical encapsulation, and aerospace industries. Enhancing the barrier properties of rubber materials is critical for prolonging product lifespan and protecting internal substances from environmental degradation. Compared to conventional rubbers, butyl rubber (IIR), synthesized via copolymerization of isobutylene and a small fraction of isoprene, exhibits inherently low gas permeability due to its saturated polyisobutylene backbone, which restricts molecular chain mobility and strengthens intermolecular interactions, thereby hindering gas penetration. However, conventional IIR increasingly fails to meet the stringent requirements of emerging applications, particularly under environmental sustainability and energy efficiency demands. Consequently, developing highly unsaturated butyl rubber with superior barrier performance is imperative for advanced sealing materials in specialized fields.
This study systematically investigates the modification conditions for epoxidized butyl rubber (E-IIR), synthesizing E-IIR with varying epoxidation degrees. Subsequent ring-opening reactions grafted diverse highly unsaturated carboxylic acids onto E-IIR, optimizing grafting efficiency to construct novel entanglement networks. Simultaneously, lamellar graphene oxide (GO) nanofillers were incorporated and surface-modified with different agents to create a "tortuous path effect," ultimately fabricating high-barrier IIR/GO composites. This work provides innovative strategies for designing high-performance rubber composites. The key findings are outlined as follows: (1) E-IIR with tunable epoxidation degrees was synthesized using a meta-chloroperoxybenzoic acid/n-hexane system. The introduction of epoxy groups enhanced material polarity, improving compatibility with polar fillers. GO was modified with silane coupling agent KH-550, successfully grafting organosilane groups to enhance interfacial compatibility and dispersion stability in the rubber matrix. Solution blending yielded high-gas-barrier materials, with optimal epoxidation (100% degree) achieved at 45°C for 1 hour.
(2) Leveraging the high reactivity of E-IIR’s epoxy groups, ring-opening and esterification reactions were conducted with docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), arachidonic acid, α-linolenic acid, and sorbic acid (SA), synthesizing a series of IIR grafted with unsaturated fatty acids. Fourier-transform infrared spectroscopy (FTIR) and ^1H nuclear magnetic resonance (NMR) confirmed successful grafting. SA-grafted IIR exhibited superior mechanical properties, thermal stability, and barrier performance, attributed to its highest grafting rate (23.7%), establishing it as the optimal matrix for subsequent studies.
(3) SA-grafted IIR was compounded with L-cysteine-modified GO (Cys-GO). The amino and thiol groups of L-cysteine reacted with carboxyl and epoxy groups on GO, introducing sulfur- and nitrogen-containing functionalities, thereby enhancing GO’s rubber affinity and dispersion. The composite demonstrated significantly improved barrier and mechanical properties, ascribed to the ideal lamellar distribution of Cys-GO, which amplified the tortuous path effect, and strengthened interfacial interactions through hydrogen bonding and covalent linkages.
By synergistically modifying IIR and GO, this study successfully developed high-barrier IIR/GO composites, offering novel insights into the design and fabrication of advanced rubber materials.
KEY WORDS: Butyl Rubber, Liquid Rubber, Graphene Oxide, Chemical Modification, Barrier Properties
