Book Description

Polyelectrolyte multilayer (PEM) assembly is a technology for building thin films with a number of useful and novel functionalities. PEMs interact favorably with proteins and other biomolecules making them potentially valuable as biomaterials. Many systems of polymers have been studied for use in PEMs, including weak polyelectrolytes such as those containing poly(acrylic acid) (PAA) and poly(allyamine hydrochloride) (PAH), which exhibit pH-dependent behavior. Properties such as thickness, swellability, mechanical stiffness, porosity (and by extention optical properties), and ability to adsorb small molecules are all controlled by the charge density of these polymers in the film and their resultant binding state. Patterning covalent binding through photo-crosslinking in addition to electrostatic binding, can locally override the native tendency to change structure with changes in pH. To achieve this, poly(acrylic acid) was chemically modified through a halide esterification reaction to incorporate photo-crosslinkable vinylbenzyl side groups, making poly(acrylic acid-ran-vinylbenzyl acrylate) (PAArVBA). The chemical modification was characterized by nuclear magnetic resonance spectroscopy (NMR) and light spectroscopy.