Photoresponsive polymers and block copolymers by molecular recognition based on multiple hydrogen bonds

Abstract

A new methacrylate containing a 2,6‐diacylaminopyridine (DAP) group was synthesized and polymerized via RAFT polymerization to prepare homopolymethacrylates (PDAP) and diblock copolymers combined with a poly(methyl methacrylate) block (PMMA‐b‐PDAP). These polymers can be easily complexed with azobenzene chromophores having thymine (tAZO) or carboxylic groups with a dendritic structure (dAZO), which can form either three or two hydrogen bonds with the DAP groups, respectively. The supramolecular polymers were characterized by spectroscopic techniques, optical microscopy, TGA, and DSC. The supramolecular polymers and block copolymers with dAZO exhibited mesomorphic properties meanwhile with tAZO are amorphous materials. The response of the supramolecular polymers to irradiation with linearly polarized light was also investigated founding that stable optical anisotropy can be photoinduced in all the materials although higher values of birefringence and dichroism were obtained in polymers containing the dendrimeric chromophore dAZO. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 3173–3184

Molecular Recognition via Hydrogen Bonding in Supramolecular Complexes: A Fourier Transform Infrared Spectroscopy Study

“…The N-H stretching region of the DAP+dAZOi mixture, on the other hand, resembles that obtained for pristine DAP, showing three main individual peaks with maxima at 3352, 3310 and 3267 cm −1 , respectively (see Figure S15 in Supplementary Materials ). This result can be explained, at least in part, by the low complexation degree with dAZOi units in this mixture, which is kept at 30%, molar %, for the sake of consistency with previous works [ 31 , 32 ]. Several signals appear associated to the vibration of N-H groups in the DAP core that are hydrogen bonded to the carbonyl group of the benzoic acid, N-H---C=O (3264 cm −1 ), confirming the formation of the DAP●dAZOi-2HB complex illustrated in Figure 6 b.…”

“…Recently, we have prepared a series of supramolecular block copolymers with diacylaminopyridine units at the side chains, to which we attach molecules containing azobenzene groups by HB [ 31 ]. Our aim is to yield light-responsive materials for optical and light-controlled delivery applications with molecular design flexibility, and to avoid potential limitations derived from covalent-based post-functionalisation of the copolymers [ 32 , 33 ].…”

Photoresponsive polymers with multi-azobenzene groups

“…135 Additionally, other studies based on hydrogen-bonded polymers with supramolecular multi-azobenzene groups in parallel have been reported. Photoinduced anisotropy, 136 orientation, 136,137 or birefringence 136,137 and the photoinduced deformation 138 of these supramolecular multi-azopolymers have been investigated.…”

Ionically conducting and photoresponsive liquid crystalline terpolymers: Towards multifunctional polymer electrolytes

“…The presence of the azobenzene-based groups will allow control of their macroscopic properties using light stimuli via changes in the local order. 15,[30][31][32][33][34][35][36]…”