Polymeric platform for the growth of chemically anchored ZnO nanostructures by ALD

The synthesis of hybrid nano-composites in which an inorganic layer is grown on a polymeric surface via chemical bonds, is a challenging goal for many applications from photocatalysis, to sensing and optoelectronics. Herein, we describe on the growth of ZnO nanostructures by an Atomic Layer Deposition (ALD) technique on polyetherimide (poly(2,2'-bis(3,4-dicarboxyphenoxy) phenylpropane)-2phenylendiimide ULTEM (R) 1000) substrates. A surface modification consisting of a thermal photooxidization process, applied for different exposure times, has been properly performed on the polymer to promote the production of ALD suitable functionalities as reactive surface-sites. The chemical anchoring of the inorganic species from the gas-phase is demonstrated by spectroscopy and mass analyses to exclusively occur on the pre-oxidized films, whilst the ZnO growth does not occur in the untreated ULTEM (R) films in the operative ALD conditions. Notably, we demonstrate that two different regimes of growth take place in the oxidized polymer as a function of the photo-exposure time. In particular, the formation of a nanostructured coating of ZnO on the polyetherimide surface is found in the case of short-time photo-exposed polyetherimide (ALD-like regime), whilst an intermixed organic/polymer layer is found on the long-time oxidized films (Vapor Phase Infiltration, VPI-like regime). The photocatalytic activity of the synthesized materials has been tested through the degradation of methylene blue dye in aqueous solution under UV light irradiation, to give a proof of concept of a possible application of the nano-composites.