Systematic optimization of poly(vinyl chloride) surface modification with an aromatic thiol

The efficient covalent functionalization of poly(vinyl chloride) (PVC), which is widely used in medical device manufacture, allows an array of potential property-enhancing surface modifications to be made. To demonstrate a general method of functionalization via substituted (functional) thiols, we describe a systematic approach to the optimization of PVC surface modification by nucleophilic substitution with 4-aminothiophenol through control of reaction conditions: solvent composition, sonication, reaction time and presence of base and/or phase transfer catalyst (PTC). Efficient thiol attachment was confirmed using solid-state NMR and Raman spectroscopies, and the extent of surface modification was quantified using ATR-FTIR spectroscopy. Sonicated samples exhibited a lower degree of modification than their statically immersed counterparts (21.7 vs 99.6 μg cm−3), and mechanical integrity was compromised. In DMSO/H2O systems with a PTC, resultant degrees of PVC surface modification were up to 12.5% higher when caesium carbonate was employed as the base than in corresponding systems with potassium carbonate.