Surface tethering of phosphorylcholine groups onto poly(dimethylsiloxane) through swelling--deswelling methods with phospholipids moiety containing ABA-type block copolymers

The surface modification of poly(dimethylsiloxane) (PDMS) substrates by using ABA-type block copolymers comprising poly(2-methacryloyloxyethyl phosphorylcholine (MPC)) (PMPC) and PDMS segments was investigated. The hydrophobic interaction between the swelling-deswelling nature of PDMS and PDMS segments in block copolymers was the main mechanism for surface modification. Block copolymers with various compositions were synthesized by using the atom transfer radical polymerization (ATRP) method. The kinetic plots revealed that polymerization could be initiated by PDMS macroinitiators and it proceeds in a well-controlled manner; therefore, the compositions of the block copolymers were controllable. The obtained block copolymers were dissolved in a chloroform/ethanol mixed solvent. The surface of the PDMS substrate was modified using block copolymers by the swelling-deswelling method. Static contact angle and X-ray photoelectron spectroscopy (XPS) measurements revealed that the hydrophobic surface of the PDMS substrate was converted to a hydrophilic surface because of modification by surface-tethered PMPC segments. Protein adsorption test and L929 cell adhesion test were carried out for evaluating the biocompatibility. As observed, the amount of adsorbed proteins and cell adhesion were drastically reduced as compared to those in the non-treated PDMS substrate. We conclude that this procedure is effective in fabricating biocompatible surfaces on PDMS substrates.