β-Cyclodextrin/Tea Tree Oil Employed Thermoset with Controlled Hydrolysis and Synergistic Antibacterial Properties

The practical application of tea tree oil (TTO) as a natural broad-spectrum antimicrobial agent is limited by high volatility, chemical instability, and compatibility challenges with conventional polymer matrices. In this study, an antimicrobial thermosetting system with controlled hydrolysis was constructed. The N, N, N ′, N ″, N ″-pentamethyldipropylenetriamine (PMD) cured samples exhibited superior mechanical and thermal properties in comparison to the N, N, N ′, N ′-tetramethyl-1,6-hexanediamine (TMHDA) or N, N, N ′, N ′-tetramethyl-1,3-propanediamine (TMPDA) cured samples. The TTO-loaded β-cyclodextrin (β-CD) was cross-linked by a rapid quaternization reaction to give the thermoset with quaternary ammonium contact-mode antimicrobial and TTO pharmaceutical antimicrobial properties. The remaining tertiary amine groups in the system provide a weakly alkaline environment, while the quaternary ammonium ester (Quat Ester) groups undergo weak base accelerated hydrolysis. The tensile strength of the cured system reached 23.69 MPa, and the antimicrobial activity against Escherichia coli and Staphylococcus aureus reached 95.27 and 95.63%, respectively; the antimicrobial performance could be further enhanced when long-chain cetyl chloroacetate (CCA) was involved in the curing (the antimicrobial activity reached 98.33 and 98.07%, respectively). The antimicrobial and pH-responsive degradation properties provide ideas for the development of degradable and antimicrobial materials for three-dimensional (3D) printing, solid disinfectants and so on.