关键词: 环氧树脂, B-N配位作用, 单组分, 储存稳定性, 可降解性

In this study, the bifunctional phenylboronic ester (BACT) was synthesized via a dehydrative condensation reaction between 1,4-benzenediboronic acid and catechol. Subsequently, a thermally reversible B-N coordinated complex (B-M) was prepared through the coordination of BACT with 4-methoxypyridine, which was then employed as a latent curing accelerator for the one-component epoxy/anhydride system (E-51/MTHPA). This molecular design strategically imparts two pivotal functionalities to the formulated resin: exceptional storage stability at room temperature (25 ℃) and markedly enhanced degradability of the crosslinked thermoset network upon exposure to alkaline conditions. Specifically, at ambient temperature, the lone-pair electrons of the pyridinic nitrogen coordinate with the vacant p-orbital of boron, forming a dative B-N bond that effectively blocks the nucleophilic catalytic activity of the pyridine moiety. This coordination temporarily suppresses its ability to initiate the epoxy/anhydride system curing reaction, thereby ensuring prolonged storage life. Upon heating to moderate-to-elevated temperatures (exceeding 60 ℃), the reversible B-N dative bond undergoes thermally induced dissociation, regenerating the active 4-methoxypyridine species to efficiently promote the curing reaction. Concurrently, beyond its role as a reversible protecting group for the catalyst, the BACT actively participates in the curing process with the epoxy/anhydride system, resulting in the covalent incorporation of more easily hydrolyzable borate ester linkages into the crosslinked network. The introduction of these dynamic covalent bonds significantly facilitates network degradation, owing to their rapid cleavage under alkaline conditions. The experimental results robustly corroborate this dual functionality. Notably, after 21 days of storage at room temperature, the experimental group (EP-B-M-0.5%) exhibited a remarkably low curing conversion of only 12.2%, along with a minimal increase in viscosity of just 0.05 Pa•s@80 ℃. In sharp contrast, the control group (EP-M-0.5%) reached a conversion of 70.8% and became fully hardened within the identical storage period, underscoring the critical role of B-N coordination in extending the usable working window. Furthermore, the mechanical and thermomechanical properties of EP-B-M-0.5% remained highly stable throughout the storage period; the tensile strength and glass transition temperature (T_g) showed only marginal variations of ＋7.6% and ＋2.2%, respectively, suggesting negligible post-curing or structural alteration during storage. In accelerated degradation tests conducted in a 1 mol/L NaOH aqueous solution, the fully cured EP-B-M-0.5% network demonstrated a degradation rate 4.5 times higher than that of the control EP-M-0.5% sample, unequivocally demonstrating the efficacy of incorporating borate ester junctions in promoting rapid hydrolytic decomposition of the thermoset. Overall, this work offers a promising and operationally simple approach for advancing the processing technology of high-performance epoxy resins while aligning with the principles of green and recyclable material development.

Key words: epoxy resin, B-N coordination, one-component, storage stability, degradation