The influence of pendant carboxylic acid loading on surfaces of statistical poly[(4-hydroxystyrene)-co-styrene]s

Copolymers of 4-tert-butoxystyrene (tBS) and styrene (S) have been prepared by free radical copolymerization and the copolymer ratios of r(tBS) = 0.97 and r(s) = 1.12 have been determined by the Kelen-Tudos method. After deprotection to 4-hydroxystyrene, alkynes were introduced by a Williamson ether synthesis with propargyl bromide and the copolymers were functionalized with pendant aliphatic or aromatic carboxylic acids by click chemistry. Differential scanning calorimetry of the copolymers demonstrates the large influence on T-g of the different functional groups and the backbone composition. In particular, aliphatic and aromatic pendant groups differ by 92 degrees C in T-g. Contact angle measurements on spin coated films have shown a maximum effect of the functional groups in the advancing contact angle at a 75/100 copolymer loading. In addition to this, X-ray photoelectron spectroscopy shows the presence of acid groups on the surface.