No abstract

is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible. h i g h l i g h t s• Poly(dimethylsiloxane) surfaces were modified with poly(ethylene glycol).• Surface modification via hydrosilylation has no impact on viscoelastic properties.• Modified surfaces exhibit lower contact angle and higher surface energy. g r a p h i c a l a b s t r a c t a r t i c l e i n f oKeywords: Poly(dimethylsiloxane) elastomers Surface modification Hydrosilylation Contact angle Surface energy Viscoelastic properties a b s t r a c tThe influence of both viscoelastic and interfacial parameters on the surface properties of elastomers is difficult to study. Here, we describe a simple route to achieve surface modification of PDMS without impacting the viscoelastic properties of the bulk. PEG modified PDMS surfaces were synthesized by two step surface modification based on hydrosilylation. The covalent grafting of PEG on the surface has been evidenced by AFM and ATR-FTIR, and its effect on the hydrophilicity characterized by static and dynamic contact angle. The static water contact angle of the PEG-modified PDMS decreases from 110• (for unmodified PDMS) to 65• . Dynamic contact angles also show a significant decrease in both advancing and receding contact angles, along with a significant increase in the contact angle hysteresis, which can be related to an increase in the surface energy as estimated by JKR measurements. The viscoelastic properties of modified PDMS are found to be quantitatively comparable to those of the unmodified PDMS. This simple method is an efficient way to prepare model materials which can be used to get a better understanding of the exact contribution of the surface chemistry on surface properties of elastomers.

A polystyrene (PS)-b-polylactide (PLA) block copolymer was prepared from the combination of atom transfer radical polymerization and ring-opening polymerization with commercially available 2,2,2-tribromoethanol as a dual initiator in a sequential two-step procedure. Hydroxyl-terminated polystyrene (PS-OH)s with various molecular weights were first prepared with polydispersity indices lower than 1.3; these provided valuable macroinitiators for the polymerization of D,L-lactide. A block copolymer with a composition allowing the formation of hexagonally packed PLA cylinders in a PS matrix was then obtained. The PS-b-PLA thin films revealed, after vapor solvent annealing, a hexagonally packed organization of the PLA cylinders, which was oriented perpendicularly to the surface of the film.