High Density Scaffolding of Functional Polymer Brushes: Surface Initiated Atom Transfer Radical Polymerization of Active Esters

Abstract

In this Article, we describe a method for the polymerization of active esters based on N-hydroxysuccinimide 4-vinyl benzoate (NHS4VB) using surface initiated atom transfer radical polymerization (SI-ATRP). Poly(NHS4VB) brushes have high grafting density and a uniform and smooth morphology, and film thickness increases linearly with reaction time. Block copolymer brushes with 2-hydroxyethyl acrylate, tert-butyl acrylate, and styrene were synthesized from surface bound poly(NHS4VB) macroinitiators. The active ester brushes show rapid and quantitative conversion under aminolysis conditions with primary amines, which was studied using grazing incidence attenuated total reflection Fourier transform infrared (GATR-FTIR) and UV-vis spectroscopy. UV-vis was also used to quantify the amount of reactive groups in polymer brush layers of differing thickness. Functionalization of the active ester pendant groups with chromophores containing primary amines showed a linear correlation between the amount of chromophore incorporated into the brush layer and brush thickness. Grafting densities as high as 25.7 nmol/cm(2) were observed for a 50 nm brush. Block copolymer brushes with buried active ester functional moieties also undergo quantitative conversion with primary amines as confirmed by GATR-FTIR. We discuss the potential of activated ester brushes as universal scaffolds for sensor and microarray surfaces, where the twofold control of functionalizable active ester polymer and block copolymers provides well-ordered, tunable microenvironments.

Post‐polymerization Modification of Polymer Brushes

“…The linear fit shown in the plot has a standard deviation of 3.2 nmol cm −2 , indicating that Py-N functionalization occurs through the brush layers for all thicknesses studied. Furthermore, the 50 nm poly(NHS4VB) film can be functionalized with 25.7 nmol cm −2 of Py-N, which is three times the amount of accessible active sites on polymer brushes than previously reported [111] and is 3 orders of magnitude greater than two-dimensional self-assembled monolayers containing activated ester functional groups [117,118].…”

“…An atomic force microscopy (AFM) topographic image of the monolayer was featureless, with a root-mean-square (RMS) roughness of 1.2 nm. The active ester monomer, n-hydroxysuccinimide 4-vinyl benzoate (NHS4VB), was prepared according to procedures listed in the literature (Figure 14.2) [108][109][110][111]. This styrenic monomer has been shown to polymerize with high reaction rates [112].…”

“…1-Aminomethylpyrene (Py-N) was used for quantitation of active ester sites, and a cyclopropenone-amine conjugate [111] was used as a masked cyclic octyne. Triethylamine (2 : 1 mol equivalents to amine) was also added as a proton acceptor [56].…”

Versatile and controlled functionalization of polyferrocenylsilane‐b‐polyvinylsiloxane block copolymers using a N‐hydroxysuccinimidyl ester strategy

“…For example the incorporation of biological molecules into BCPs to enhance their material properties has already been demonstrated to be a successful approach. 42,43 To explore this methodology the NHS ester functionalised PFS68-b-PDMS652/PMVS67 and benzylamine were dissolved in THF and stirred at room temperature for 16 h. The polymer was precipitated into methanol several times and dried in vacuo to give a gummy orange solid 4a. To test the generality of this approach a range of different primary amines including biorelevant c) High PDI was obtained by GPC due to interaction of the block copolymer with the column; d) PDI could not be determined by GPC due to strong interaction of the block copolymer with the column which led to a broad peak (see Supporting Information Figure S3).…”

Mitigated reactive oxygen species generation leads to an improvement of cell proliferation on poly[glycidyl methacrylate‐co‐poly(ethylene glycol) methacrylate] functionalized polydimethylsiloxane surfaces

“…Among them, surface-initiated atom-transfer radical polymerization (SI-ATRP) has been proved to be effective in producing nonfouling and bioactive surface. 23,24 Wu et al 25 engineered polymer brushes of oligo(ethylene glycol) methacrylate (OEGMA) on PDMS to prevent cell adhesion. The OEGMA brush layer can be further activated to tether bioadhesive ligands, such as FN, using standard 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide/N-hydroxysuccinimide ester (EDC/NHS) chemistry.…”