Wrinkle pattern on PLLA induced by stress of polymer-metal bilayer

This paper is focused on study the effect of the PLLA modification with Ar plasma followed by deposition of thin layers of metal (Au, Ag) and studying of thermal stress influence on the properties of the PLLA substrate. Particular attention was devoted to changes of surface morphology and roughness which was studied with atomic force microscopy and laser confocal microscopy. The wettability of the surface was characterized by measurement of contact angle and the subsequent calculation of the surface energy. The chemical composition was determined by XPS spectroscopy. The main aim was devoted to construction of wrinkle-like surface pattern on the basis of polymer-metal bilayer stress. After heat treatment of PLLA (non-treated or treated with plasma) deposited with thin metal layers the wrinkle-like structure was formed. Depending on the thickness of deposited layers, the structure exhibited partial orderliness and preferred direction of the structure across the whole surface was observed for some combination of input parameters. Surface energy of PLLA-metal system and in particular its polar and nonpolar component, as well as the concentration of the metal on the surface is strongly influenced by the pretreatment of substrate with plasma. By plasma treatment of PLLA with subsequent deposition of metal nanolayer and consequent thermal treatment materials useful in tissue engineering can be constructed, for example cell carriers or manufacture of integrated circuits based on biopolymers can be enhanced.