Driving Polymer Brushes from Synthesis to Functioning

Abstract

The great success of controlled radical polymerizations has encouraged researchers to develop more facile and robust approaches for surface-initiated polymerizations (SIPs) to fabricate polymer brushes, even for non-experts. In recent years, external-stimuli-mediated radical polymerization methods have come to the fore as SIPs because of their less rigorous synthetic procedures and high controllability, which expand the opportunities for synthesizing macromolecules with desired chemical compositions and structures, as well as tailor-made polymers and bioconjugates that show broad applicability and physiological compatibility. This review discusses the latest developments in surfaceinitiated polymerization methods, in particular, external-stimuli mediated atom transfer radical polymerization (ATRP), photo-induced polymerizations, and reversible addition-fragmentation chain transfer (RAFT) polymerization, as well as other methods and their combination for the application in surface grafting. The implementation of these methods is of great interest due to their unique possibilities to temporally control a polymerization process, fast and straightforward polymerization, and environmentally benign features, which lead to established and emerging applications in biolubrication, antifouling, and biosensing.

Recent Advances in Antifouling Surface Polymer Brushes

“…112,113 The use of different controlled polymerization technologies to prepare surface polymer brushes via a "grafting from" approach has been well-documented in many excellent reviews. 12,30,111,114 Therefore, this review article would not deal with this aspect repeatedly. However, we would like to highlight here the uses of some emerging controlled polymerization technologies mediated by external stimuli such as light or electricity other than conventional heat for surface polymer brush synthesis.…”

“…In contrast to the “grafting to” method, the “grafting from” method mediated by surface-initiated polymerization provides precision and controllability over the length of polymer brushes and, moreover, it minimizes to a great extent the steric hindrance effect encountered by macromolecular reactions. Thus the “grafting from” method is particularly advantageous to prepare surface polymer brushes with high grafting densities. , The use of different controlled polymerization technologies to prepare surface polymer brushes via a “grafting from” approach has been well-documented in many excellent reviews. ,,, Therefore, this review article would not deal with this aspect repeatedly. However, we would like to highlight here the uses of some emerging controlled polymerization technologies mediated by external stimuli such as light or electricity other than conventional heat for surface polymer brush synthesis .…”

“…In most cases, covalent tethering of antifouling polymers to material surfaces is preferred as it leads to surface polymer brushes with long-term stability and durability even under adverse environmental conditions. 30 The two most commonly used methods to prepare antifouling polymer brushes are "grafting to" and "grafting from". 31 Both rely on the use of highly efficient anchor chemistries to graft polymers or polymerization mediators to material surfaces.…”

Surface-Initiated Zerovalent Metal-Mediated Controlled Radical Polymerization (SI-Mt0CRP) for Brush Engineering

“…Surface-tethered polymer brushes have been a versatile approach to tailoring the chemical and physical properties of surfaces and interfaces. − Growing demands for generating diverse functional polymer brushes advance the development of innovative and effective polymerization methods. − One of the most prevailing strategies is surface-initiated controlled radical polymerization (SI-CRP), also denoted as surface-initiated reversible-deactivation radical polymerization (SI-RDRP), − which is generally performed on substrates modified with a self-assembled monolayer (SAM) of initiators, tethering polymer chains to the substrate by one end , and thus endowing the arbitrary surfaces with the desired placement of groups and targeted functions. , …”

Oxygen Tolerance during Surface-Initiated Photo-ATRP: Tips and Tricks for Making Brushes under Environmental Conditions

“…Typical SI-photoATRP do not necessarily require the presence of an initiator in solution (which would act as a sacrificial initiator) . However, this was often employed during “normal” SI-ATRP to increase the concentration of Cu II -based deactivators in polymerization mixtures and provide an estimate of the molar mass of the surface-grafted polymer, − or to increase the viscosity of the reaction medium …”