Preparation of side‐on bisazobenzene‐containing homopolymers and block copolymers via ATRP and studies on their photoisomerization and photoalignment behaviors

Abstract

The preparation of a series of novel homopolymers and copolymers containing bisazobenzene chromophores with side‐on structure in the side chains via atom transfer radical polymerization (ATRP) were presented. UV–vis spectra of the thin films of these polymers under irradiation of 488 nm Ar+ laser suggested that the photoisomerization of the bisazobenzene chromophores happened mainly on one of the two azo groups in the bisazobenzene chromophores with similar probability due to their side‐on structure. Good photoalignment behaviors of these polymers were proved by photoinduced birefringence measurements because side‐on structure permitted the two azo groups in the bisazobenzene chromophores both participated in the trans–cis–trans photoisomerization cycles equally to induce the whole chromophore reorientation. Furthermore, the reorientation axis located at the middle of chromophore decreased the sweep volume during photoalignment. The impetus for this study was to evaluate the photoisomerization and photoalignment process of side‐on bisazobenzene‐containing polymers and to find possible applications in the photosensitive devices. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3460–3472, 2007

Molecular-level interactions of an azopolymer and poly(dodecylmethacrylate) in mixed Langmuir and Langmuir–Blodgett films for optical storage

“…The lines are drawn to guide the eye. [4,10,24,35], copolymers [5,10,17,36,37] and blends [38,39] with the advantage of a relatively small writing time. The comparison of the two mixtures indicated that 41% molar fraction of azopolymer are sufficient for the photoinduced birefringence, with an optimized writing process using 1.4 mW of laser power.…”

Synthesis, characterization, and photo‐responsive properties of Y‐shaped amphiphilic azo triblock copolymer

“…Firstly, an ATRP initiator with two specific functional groups (N-Ph) is prepared. Then, the precursor azo polymer with dianilino groups (P6OCN 16 ) is polymerized through ATRP with the obtained initiator. Finally, the Y-shaped amphiphilic azo triblock copolymer is obtained by the macromolecular azo-coupling reaction between P6OCN 16 and the diazonium salt of PEG 43 Figure 1 shows the 1 H NMR spectrum with resonance signal assignments of the newly synthesized ATRP initiator, which confirms that the ATRP initiator is successfully synthesized.…”

“…38 16 ) CuBr (57.4 mg, 0.4 mmol) was added into a schlenk flask, and then the flask was degassed and back-filled with nitrogen for three times. After this step, deoxygenated ATRP initiator 3,5-bis(2-ethyl(phenyl)aminoethoxy)benzenemethyl 2-bromo-2-methyl-propionate (0.116 g, 0.2 mmol), azobenzene monomer 6-(4-cyano-azobenzene-4 0 -oxide)-hexyl methacrylate (6-OCN) (1.56 g, 4 mmol), 1,1,4,7,10,10-hexamethyl-triethylenetetramine (HMTETA) (110 lL, 0.4 mmol) and anisole (2.0 mL) were added.…”

“…[8][9][10] Making use of these unique properties, the applications of amphiphilic block copolymers as nanoreactors, drug delivery systems, biodiagnostics, nanolithography, ultrahigh-density storage media, and nanoporous membranes have been actively explored. [11][12][13][14] The synthesis of well-defined amphiphilic block copolymers was achieved by the development of living/controlled polymerization techniques, especially by atom transfer radical polymerization (ATRP), [15][16][17] ring-opening metathesis polymerization (ROMP), 18 and reversible addition-fragmentation chain transfer polymerization (RAFT). 19 However, in these typical polymerization techniques, macroinitiators and/or macromolecular chain transfer agents are needed to fabricate the final block copolymers, and in some particular cases, the reactivity of the macroinitiators and/or the second monomer is not high enough to form the required block copolymers completely.…”

Highly ordered nanoporous thin films by blending of PSt‐b‐PMMA block copolymers and PEO additives as structure directing agents

“…envisaged for these materials. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] It is now well established that the structural characteristics of block copolymer thin films can be controlled by manipulation of molecular weight, block volume fraction, and the interaction parameter, v. 1,4,5 In turn the orientation of the block domains in thin films is governed by boundary conditions such as commensurability and interfacial interaction between blocks and substrates. 1,4,5 In controlling the orientation of block copolymers in thin films, several strategies have been employed including surface modification, [17][18][19][20] solvent annealing, 21 electric fields, 22 graphoepitaxy, 23 chemical prepatterning, 24,25 shear, 26 etc.…”