Synthesis and self‐assembly of diblock copolymers bearing 2‐nitrobenzyl photocleavable side groups

Abstract

The light-responsive behavior in solution and in thin films of block copolymers bearing 2-nitrobenzyl photocleavable esters as side groups is discussed in this article. The polymers were synthesized by grafting 2-nitrobenzyl moieties onto poly(acrylic acid)-block-polystyrene (PAA-b-PS) precursor polymers, leading to poly(2-nitrobenzyl acrylaterandom-acrylic acid)-block-polystyrene (P(NBA-r-AA)-b-PS) block copolymers. The UV irradiation of the block copolymers in a selective solvent for PS led to the formation of micelles that were used to trap hydrophilic molecules inside their core (light-induced encapsulation). In addition, thin films consisting of light-responsive P(NBA-r-AA) cylinders surrounded by a PS matrix were achieved by the self-assembly of P(NBA-r-AA)b-PS copolymers onto silicon substrates. Exposing these films to UV irradiation generates nanostructured materials containing carboxylic acids inside the cylindrical nanodomains. The availability of these chemical functions was demonstrated by reacting them with a functional fluorescent dye. V C 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 50: 599-608, 2012

Stimuli-Responsive Polymers and their Potential Applications in Oil-Gas Industry

“…Moreover, the o-nitrobenzyl group could also be employed as the photochromic side groups of the amphiphilic di-block copolymers. [60][61][62] The hydrophobic segment possessing an aryl methylester group, which is connected with the ONB, is linked to the polymer chain backbone. The UV irradiation will cleave the photochromic moieties as shown in Fig.…”

o -nitrobenzyl acrylate is polymerizable by single electron transfer-living radical polymerization

“…However, the final molar contents of NBA units in P(TEGEA-co-NBA) blocks remain low (11% and 17% in the diblock and triblock, respectively). More recently, poly(o-nitrobenzyl acrylate-co-acrylic acid)-b-polystyrene (P(NBA-co-AA)-b-PS) diblock copolymers were described 19 via a chemical modification of PAA-b-PS with 2-nitrobenzyl bromide, 16 due to the Additional Supporting Information may be found in the online version of this article.…”

Synthesis and Self-Assembly of o -Nitrobenzyl-Based Amphiphilic Hybrid Polymer with Light and pH Dual Response

“…Initially, the absorption band at 260 nm decreased gradually and then leveled off with further increasing the irradiation time. Meanwhile, absorption band at 310 nm appeared and increased in intensity, corresponding to the presence of o ‐nitrosobenzaldehyde generated from the photocleavage reaction . A light yellow precipitation gradually appeared with the increase of irradiation time.…”