Role of chain architecture in the adhesion of block copolymers

We have used Johnson-Kendall-Roberts contact mechanics methodology to study the self-adhesion of block copolymers. The block copolymers studied contai n building blocks that have different physical states as well as different dynamic characteristics. The polymers chosen are poly(styrene)poly(isoprene ) (PS-PI), poly(styrene)-poly(ethylethylene) (PS-PEE) diblocks and PS-PI-PS , PS-PEE-PS triblocks that have the tail and looped chain surface architect ures, respectively. Our results for unloading of the diblock/triblock mixtu res, where two surfaces are separated by decreasing the amount of compressi on, show a maximum in adhesion vs mixture composition when the contact time is short. For contact times longer than 30 min, only unloading of triblock -dominated mixtures shows considerable buildup of adhesion with time. The s urface energies obtained from loading experiments do not show any detectabl e influence of chain architecture on the thermodynamic work of adhesion.