A General Approach to Predict and Tailor the Nanoscale Permeability of Comb-Shaped Polymer Coatings

Comb-shaped polymers such as poly(oligoethylene glycol monomethyl ether) methacrylate) (pOEGMA) are used to produce molecular sieving coatings on proteins. The mechanisms and phenomena implicated in the experimentally observed sieving properties have been recently characterized by simulation. These result from an interplay between steric hindrance, microenvironmental effects, and modified protein dynamics. Steric hindrance, in particular, is expected to vary considerably as a function of the geometric parameters of the system (protein size, polymer size, grafting density, etc.). In this work, the steric and size-selective permeability characteristics of comb-polymer coatings are systematically explored across a very broad parameter space to gain a universal and predictive view of molecular sieving, for application to systems with different dimensions. All features of the data can be understood when three distinct regimes are considered: i) no-interactions, ii) weak-interactions, and iii) strong-interactions between adjacent polymer chains. Primary and secondary considerations are provided for tuning coating properties to adjust the size threshold of molecular sieving. The corresponding qualitative physical pictures and quantitative analyses give a robust framework to understand molecular sieving that will accelerate the development of future coatings.