Chain Extension of Stimuli‐Responsive Polymer Brushes: A General Strategy to Overcome the Drawbacks of the “Grafting‐To” Approach

Abstract

Stimuli-responsive polymer brushes are smart materials for the design of bio-interactive and responsive interfaces. The "grafting-to" approach is a convenient preparation procedure that allows the modifi cation of surfaces with preformed and most notably well-defi ned functionalized macromolecules. However, the shortcoming of this approach is an intrinsic limitation of the grafting density, which in turn affects the stimuli-responsive properties of the brush system. Here, a general strategy to overcome this limitation and to simultaneously improve the switching behavior of a temperature-responsive poly( N -isopropylacrylamide) (PNiPAAm) brush is reported. A technically simple processing step is used in combination with the thermal azide-alkyne cycloaddition to perform the chain extension of alkyne-functionalized PNiPAAm brushes with azide-functionalized PNi-PAAm molecules.

From Self-Assembled Monolayers to Coatings: Advances in the Synthesis and Nanobio Applications of Polymer Brushes

“…More recently "Click" chemistry has been used to form polymer brushes with high grafting efficiency, minimized side reactions and to provide relatively mild reaction conditions which avoid any photochemical or thermal degradation of chemical functionalities [67,[78][79][80][81][82]. Paoprasert et al showed that Cu(I)-catalyzed Huisgen 1,3-dipolar cycloaddition of azide group with alkyne group was an efficient route to form conducting polymer brushes with controlled film thickness and chain density (Figure 4a) Figure 4b) [83,84].…”

“…Examples include the use of crosslinked or multiple-point grafted poly(glycidyl methacrylate) (PGMA) thin coatings or epoxy terminated silane SAMs to attach amine-or acid-terminated polymers [62][63][64][65][66][67][68], a reductive alkylation reaction between amine-functionalized surface and aldehyde-terminated polymers to form an imine bond which is subsequently reduced [69,70], Au-S bond formation between thiol-terminated polymer and Au surface [71,72], thiol-disulfide exchange reaction using thiol-terminated block copolymers to prepare for cleavable polymer brushes on silica particles [73,74], an amidation reaction of N-hydroxysuccinamde protected carboxylic acid terminated polymers and amine functionalized SAMs on surface [75], Diels-Alder ligation reaction between cyclopentadiene and maleimide [76], and a condensation reaction between silane-terminated polymers and silanol groups on an oxide surface [77].…”

Molecular Dynamics of Swollen Poly(2-vinylpyridine) Brushes

“…There is a broad range of interests on polymer brushes with respect to fundamental and applied research. Different synthesis strategies have been established for various materials with the goal to tune surface properties by design of the tethered polymer layer resulting in various types of systems like mixed brushes and composites with nanoparticles or bifunctional polymers. − …”

Investigating organic multilayers by spectroscopic ellipsometry: specific and non-specific interactions of polyhistidine with NTA self-assembled monolayers

“…A high-performance sensor needs to integrate a specific binding scheme with a sensitive, non-destructive transduction of the binding event into a measurable signal. Optical methods based on optical reflectivity, such as surface plasmon resonance (SPR) and ellipsometry, allow for label-free, non-invasive, in situ monitoring of molecular adsorption/desorption at surfaces [ 34 – 40 ]. While SPR-based methods require supports with specific plasmonic properties, ellipsometry methods can be employed on a variety of reflecting solid surfaces.…”