Invertible Polymers for the Stabilization of Nanoparticles

Novel amphiphilic polyesters with both hydrophilic and hydrophobic functionalities being alternately distributed along polymer backbones have been synthesized and characterized. The polyesters are soluble in organic and aqueous media and reveal the formation of inverse architectures whose behavior could be correlated to their chemical structure. This work offers a new approach to building up self-adjustable invertible polymer coatings at solid surfaces. The approach is based on a two-step process. In the first step, the surface of dispersed titania or silicon wafers has been functionalized with the aid of a reactive copolymer, viz., poly(styrene-alt-maleic anhydride) (PSM), to which, in the second step, the chains of amphiphilic polyester have been tethered. The modified titania can form stable suspensions in both polar and nonpolar media. An environmentally induced switching of the surface properties has been observed via the AFM of silicon wafers with tethered polyester chains.