Itaconate-Based Clickable Surface-Anchored Cross-Linked Polymeric Coatings

Reactive coatings are those that permit installation of desired segments in a postcoating step; several approaches have been developed to design polymers that can covalently anchor to the substrate while at the same time providing a handle for further functionalization. Here, we present a simple approach to prepare surface-anchored coatings that can be functionalized with desired segments in a postcoating step; to achieve this, we prepared a heterodiester of itaconic acid (IA), namely, 2-hydroxyethyl, propargyl itaconate (HEPI), which upon free-radical-initiated polymerization yielded a polymer, PHEPI. This polymer is endowed with three attractive features: (i) the pendant hydroxyl groups can react with Si–OH groups on suitably treated glass/silicon surfaces; (ii) the pendant propargyl groups can help install chosen segments onto the coating, via azide–alkyne reaction, to render the desired properties to the surface, and (iii) thermally induced cross-linking of the coating that occurs at ∼140 °C, which helps create robust surface-anchored coatings of desired thickness. Derivatization of PHEPI coatings was easily done by treatment with a variety of organic azides, such as PEG-azide, cetyl azide, fluoroalkyl azide, etc., to yield surfaces with distinct characteristics; the derivatized surfaces were characterized by contact angle measurements, infrared, and X-ray photoelectron spectroscopy. Further, we demonstrate that this polymer can also be spray-coated onto paper, and thus it serves as a reactive primer for covalently modifying their surface properties at a late stage. In addition, we also show that the propargyl groups in Si-coated PHEPI can be clicked using a photoinitiated thiol-yne reaction, which in turn permitted the photopatterning of coated substrates. In summary, this simple approach, starting from readily available and biosourced IA, provides ample scope for further elaboration to generate designer surfaces that could form the basis for a range of potential applications.