Amphiphilic Chitosan-g-Polyisobutylene Graft Copolymers: Synthesis, Characterization, and Properties

The amphiphilic acylated chitosan-g-polyisobutylene copolymers (ACS-g-PIB) could be achieved via highly effective nucleophilic substitution of living PIB chains carrying the oxonium ion (PIB-THFn+) with −NH2 side groups along the ACS backbone, in which the grafting number (GN) was mediated by changing [PIB-THFn+]/[−NH2]. The obvious microphase separation micromorphology formed in copolymers due to incompatibility between the hydrophilic backbone and hydrophobic branches. Crystallization from the ACS backbone in copolymers became weaker while roughness and water contact angle on copolymer surfaces increased with increasing GN and length of PIB branches, leading to a great improvement in antiprotein adsorption. The copolymers served as pH-sensitive drug carriers for total release within 72 h at pH = 6.3. The ACS-g-PIB with uniformly dispersed silver nanoparticles (2.4 ± 0.5 nm) have good antibacterial properties to both Escherichia coli and Staphylococcus aureus. To the best of our knowledge, this is the first example ACS-based amphiphilic graft copolymers for potential application in the biomedical field.