SILICONE RESINS CONTAINING POLYSTYRENE AND POLY(t-BUTYL ACRYLATE) GRAFTS AS FOULING RELEASE COATINGS FOR MARINE APPLICATIONS

摘要

Toughening of silicone elastomers by grafting of high Tg polymers such as polystyrene (PS) and poly(t-butyl acrylate) (P(t-BA)) was explored. The exceptional properties of silicones makes them very versatile for various applications, however silicone elastomers are mechanically weak. Grafting of the silicones using various functionalities such as hydrophilic and hydrophobic moieties can improve the properties of silicones. Silicones and modified silicones are being used for marine coatings applications. This paper will examine the use of automated methods in combination with a high throughput approach for the synthesis of silicone resins containing PS and P(t-BA) grafts using Atom Transfer Radical Polymerization (ATRP) and click chemistry. Herein, ATRP of styrene and t-BA was carried out using a Chemspeed Autoplant A100~(TM) parallel reactor system. Excellent monomer conversion was obtained for styrene and t-BA and PDI was as low as 1.2 in both the cases. The bromine terminated PS and P(t-BA) were functionalized with azide groups using sodium azide. Using CuBr-PMDETA the azide groups were reacted with propargyl acrylate via a 1,3-dipolar cycloaddition reaction to obtain a acrylate terminated PS and P(t-BA). The polymers were characterized by NMR, FTIR, Rapid GPC and MALDI-TOF MS and molecular weights were in good agreement. The acrylate terminated PS and P(t-BA) were then reacted with polymethyl hydrosiloxane using Karstedt's catalyst to obtain the grafted silicone resin. The silicone resins were then characterized by NMR and Rapid GPC. The silicone resins were then crosslinked with vinyl terminated polydimethyl siloxane to get the coating. The coatings were characterized by contact angles and surface energies were measured.