Orthogonal surface‐grafted polymer gradients: A versatile combinatorial platform

Abstract

Orthogonal polymer brush gradients are assemblies of surfaceanchored macromolecules, in which two material properties of the grafted chains (e.g., grafting density, molecular weight) vary independently in orthogonal directions. Here, we describe the formation and applications of two such orthogonal assemblies, involving: (1) molecular weight and grafting density (MW/r) gradients of a given polymer and (2) molecular weight gradients (MW1/MW2), of two different polymers. Each point on orthogonal gradient substrate represents a unique combination of the two surface properties being varied, thus facilitating systematic investigation of a phenomenon that depends on the two said properties. We illustrate this point by employing orthogonal structures to study systematically: (1) formation of polymer brush-nanoparticle composite assemblies, (2) protein adsorption and cell adhesion, and (3) chain conformations in tethered diblock copolymers exposed to selective solvents.

Permanent, non-leaching antibacterial surfaces—2: How high density cationic surfaces kill bacterial cells

“…The density of polymers grown from a surface has been tuned rationally by controlling the initial initiator concentration on the substrate [25,[35][36][37][38][39][40][41]. In a variation of this process, Jones et al [34] reported controlling the polymer density of ATRP-synthesized brushes by varying the concentration of the initiator molecules in self-assembled monolayers.…”

Gradient and Microfluidic Library Approaches to Polymer Interfaces

“…In addition, a key feature of grafted statistical copolymers is that they present stable and intimate blends of disparate chemical species. Since the different monomers are bound within the same chains, the system will not undergo lateral clustering typical of mixed homopolymer brushes [61], or segment segregation seen in block copolymer brushes [45,58], both of which can cause spatial chemical heterogeneities on the scale of 10 nm or more. Accordingly, if local surface-chemical homogeneity is needed from a surface chemistry gradient library, statistical copolymer gradients present an advantage.…”

“…In order to create more robust and diverse surface chemistry gradients, NIST researchers turned to surface-initiated polymerization (SIP) techniques [43,44] to create libraries of grafted polymer "brushes" that would systematically change in their molecular composition and architecture. In this endeavor, the pioneering work of Genzer and coworkers [45][46][47][48] provided examples to build upon, including the creation of gradient libraries of polymer brush length and grafting density.…”

Combinatorial and High‐Throughput Methods in Macromolecular Materials Research and Development

“…[74][75][76][77][78] Several researchers have made surface-grafted polymers that have gradients in variables such as polymer chain length, composition, and graft density. [79][80][81][82][83][84][85][86][87][88][89] …”