Coatings World - July 2012

Re-chargeable Coatings:

Innovative Approach

to Functionalization-
on-Demand

By Juan Carvajal, Matt Schwausch, Steve McDaniel, Jon Hurt, Melinda Wales*

Reactive Surfaces, USA;

Eric Williams, Dwaine A. Braasch, James Rawlins

The University of Southern Mississippi, School of Polymers and High Performance Materials, USA

Abstract

Functionality is the most recent advancement in coatings technology that adds significantly to the traditional role of a coatings system. Natural biomaterials, such as proteins and peptides, provide an enormous resource of functional additives that are non-persistent in the environment, non-toxic and renewable. Biomolecules, such as peptides, antibodies and receptors, have provided many distinct non-catalytic activities in natural environments. By focusing on the unique and specific binding properties of these non-catalytic molecules, biobased additives are being created which will provide a new and innovative function to coatings systems: “recharge-ability”. Being able to change or renew a biocide or other functionality, without recoating adds a new dimension to the coated surface. The current state of research in the development of biomaterials for functional coatings, including antifouling and antimicrobial surfaces, with specific examples of recharging will be presented.

Innovation in Materials Science: From
Nonselective Absorption & Release to Artificial
Receptors

In its most simple embodiment, the concept of a“rechargeable” coating can be a cross-linked polymer or copolymer that would absorb a target molecule, release it under specified conditions and remain receptive to re-absorption of the target [1]. Nature has provided a large number of molecules that already perform highly efficient small molecule recognition and/or catalysis. These molecules, such as enzymes, antibodies and membrane receptors are molecular machines that can contain a combination of small molecule binding, transport, release, and/or catalytic functionalities. Current approaches in material science involve mimicking natural molecules to create artificial receptors and molecularly imprinted polymers that have a release/re-absorption property. Artificial receptors are typically created by“im-printing” binding sites or receptor structures within a polymeric surface, thus creating the ability to selectively and reversibly bind molecules of interest. A target molecule is employed as a template around which interacting and cross-linking monomers are polymerized to form a block that contains a number of cavities each with a template molecule inside (Fig. 1). The resulting binding sites are complementary to Fig 1. A target molecule serves as a template around which a cross-linked polymeric material forms a number of hollows conformed to the target molecule. the target molecule in size and shape [2]. After polymerization, the template is removed and the binding sites that have been imprinted on the polymer are capable of selectively rebinding to the target molecule.