Preparation And Performance Of Polysiloxane Coating Material Modified By Antibacterial Groups

Polysiloxanes possess a variety of unique and superior properties, such as low surface energy, aging resistance, corrosion resistance, climate resistance, good physiological inertness, fine biocompatibility, and so on. Polyurethanes (PU) are known for their excellent mechanical properties, good adhesion and fast-curing feature. Polysiloxane modified PU, taking advantage of the good properties of both polysiloxanes and PU, are broadly used as functional coating materials. These materials can be further applied in the field of biomedicine and marine antifouling by introducing the antibacterial groups into the copolymer chain.In order to obtain the copolymer network with low surface energy and antibacterial property, a series of hydroxy-terminated polydimethylsiloxanes (PDMS) grafted by quaternary ammonium salt (QAS) side chain with different degrees of polymerization were synthesized via hydrolytic polycondensation and quaterisation. The structures and compositions of the final products were confirmed by FT-IR, ’H-NMR and GPC. Modified PDMS were cross-linked with polyisocyanate to obtain cured polyurethane coatings and the surface properties and antimicrobial performance were characterized. The results showed that when the molar contents of QAS in PDMS varied from 10% to 30%, the critical surface energy of films kept in the range of 23.55-26.88 mN/m, where minimal fouling adhesion was achieved according to Baier curve. The bactericidal rates of the coatings to E. coli and S.aureus were higher than 97% while the content of QAS was above 20%.To further reveal the relationship of the coating surface property and antibacterial performance and the structure composition of the copolymer, a series of polyurethane coatings with different copolymerization compositions and QAS contents were designed and synthesized. The surface element composition and microfacies morphology of the copolymers were measured by XPS and AFM. Results showed that the enrichment of the PDMS grafted by QAS was affected by polysiloxane chain and QAS groups, simutaneously. A positive correlation between antibacterial activity towards E. coli and surface concentration of N+ was observed. Within a certain range, these copolymer coatings showed excellent properties of low surface energy and antibacterial activity. While the density of QAS in PQMS reached 30%, the pendant QAS chains haul the polysiloxane segments back into polyurethane bulk leading to obvious decreas on the ratio of Si and N+ concentration on surface. Thus, the concentration of QAS in surface was less than it in bulk.