Preparation Of Controlled Release Chitosan Microspheres And Research Of Antifoulants' Controlled Release Performance

Sustainable release of antifoulants from coatings is the basis of protecting ship hulls from biofoulings adhered. The research purpose of this paper is to prepare antifoulants loaded chitosan (CS) microspheres which can slow down the release rate of antifoulants, thus,prolong the lifetime of antifouling paint. To understand the mechanisms of antifoulants'release, we have explored the release kinetics of antifoulants in coatings.First, we prepared Seanine-211 loaded CS beads with the method of injection.Orthogonal tests with three levels and three factors were designed to prepare 9 groups of CS gel beads with different technological parameters. The impacts of CS concentration, ratio of CS and drug, concentration of crosslinker on the gel beads were investigated. The morphology and composition of CS gel beads were characterized using SEM and FT-IR. We studied influence of different preparation condition on the encapsulation efficiency, swelling rate and cumulative release rate of the gel beads. Particle sizes of the beads were approximately 1mm with high encapsulation efficiency. Optimum beads were received while concentration of CS is 5%. ratio of CS and Seanine-211 is 10:1 and crosslinker concentration is 2.5%.On the basis of loading antifoulants successfully, we prepared CS microspheres with the evolved emulsion-crosslinking method. Also, orthogonal tests with three levels and three factors were designed to prepare 9 groups of CS microspheres. Same impacts were investigated as in CS beads. The morphology, composition, particle size and crystalline structure were characterized. We explanatorily researched how the preparation technology would affect the encapsulation efficiency, cumulative release rate and algae inhibition performance of CS microspheres. The conglutination of CS microspheres decreases with the increasing of CS % resulting in low boost release; the increase of crosslinker concentration leads to stronger vibration of the Schiff base. We obtained the optimized preparation parameters as 4% CS, 5:1 ratio and 2.5% crosslinker. The diffusion of Seanine-211 from microspheres accords with pseudo-Fickian law. The fact that these controlled release CS microspheres could prolong antifouling lifetime was proved by algae inhibition experiments.To explore the release kinetics of antifoulants from self-polishing paint, we tested the release rates of antifouling coatings prepared with different kinds of polymers. Release rates of Cu2+ and Zn2+ from Zn-polymers and Si-polymers were studied respectively, while the polymers were made by different monomer contents. Release rates of Cu2+ and Zn2+ from Zn-polymer was inversely proportional to the pH value of artificial seawater; on the contrary,only release rate of Cu2+ from Si-polymer had the same trend while the two kinds of ions'release rates were much lower than that of Zn-polymer.