An amphiphilic diblock copolymer composed of a photoresponsive dialkoxycyanostilbene polymethacrylate and poly(ethylene oxide) (PDACS‐b‐PEO) was synthesized and its photophysical and aggregation properties were investigated. The amphiphilic nature of the polymer caused it to self‐assemble in water, and dynamic light scattering studies indicated formation of spherical aggregates with an average size of 160 nm. Atomic force microscopy images of dried films cast from solutions containing the polymer aggregates revealed supramolecular aggregates with a spherical morphology. Photoisomerization of the stilbene chromophore in PDACS‐b‐PEO on UV irradiation resulted in the destruction of the self‐assembled superstructures which could be attributed both to change in shape of the chromophore from the linear trans isomer to the bent cis isomer which would hinder self‐aggregation of the molecules and the higher dipole moment of the cis isomer leading to a reduction of the hydrophobic nature of the stilbene containing block of PDACS‐b‐PEO. It was observed that hydrophobic dyes such as curcumin could be encapsulated within the hydrophobic interior of the spherical micellar aggregates from which the encapsulated dye could be released on UV irradiation. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

A new photoresponsive amphiphilic triblock copolymer, poly(pyrenylmethyl methacrylate)-block-polystyreneblock-poly(ethylene oxide) (PPy-b-PSt-b-PEO), was synthesized using atom-transfer radical polymerization. Formation of colloidal aggregates of the polymer was observed in solutions under controlled conditions due to the amphiphilic nature of the polymer. Irradiation of the polymer aggregates using UV light resulted in the photodissociation of 1-pyrenemethanol units from the polymer back-bone resulting in break-up of the aggregates mainly due to the hydrophilic nature of the residual polymer. The use of these polymer aggregates to trap hydrophobic fluorescent dyes in water and its controlled release on exposure to UV light has also been explored.

The use of a new block copolymer made up of poly(azobenzene methacrylate) (PMAzo) and poly(3-O-4-vinylbenzoyl-D -glucopyranose) (PBG) is described for the solubilization of waterinsoluble dyes such as Nile Red in aqueous solutions. This polymer, which is abbreviated as PMAzo -b-PBG, self-assembles into spherical aggregates in water as confi rmed by atomic force microscopy. UV irradiation of the aqueous polymer solution destabilizes the aggregates brought about as a result of the trans-cis isomerization of the MAzo units. Dissociated aggregates reunite to form tubular aggregates when the solution is irradiated with 450 nm light. Nile Red, which is a hydrophobic dye, can be incorporated into these aggregates and subsequently released using UV light. The encapsulation, release, and re-encapsulation of Nile Red are studied using fl uorescence spectroscopy. of wide range of glycopolymers with controlled architectures and functionalities, [15][16][17] it is often better to use polymerizations of sugar-carrying monomers for synthesizing linear glycopolymers of well-defi ned architectures. [ 18 ] It is well known that carbohydrates are used significantly in cellular biorecognition events and hence these carbohydrate-based interactions are used in cellular-specifi c drug delivery. Glycopolymers are useful functional materials due to their solubility, high hydro philicity, strong hydrogen bonding ability, and the presence of many chiral centers. [ 19 ] Such polymers fi nd various biomedical and biochemical applications for use as biomimetic analogues, [ 20 ] drug-delivery systems [ 21,22 ] and as surfactants. [ 23 ] Due to its biocompatibility, biodegradability, and water solubility, glycopolymers are used as biomaterials that can mimic its natural analogue in shape and functions. Because of their unique properties, amphiphilic glycopolymers with sugar units as the hydrophilic segments have been found to form well-defi ned aggregates in water. [24][25][26][27][28][29][30] Such aggregates can be used as a model system for bioinspired structure formation and as drug carriers. [ 31,32 ] Polymeric micelles that respond towards pH, [33][34][35] heat, [ 36,37 ] light, [38][39][40][41][42][43][44][45][46] or redox potential [ 47,48 ] S. Menon et al.

Stimuli responsive luminescence switching, liquid crystalline and gelation properties of 1,3,4-oxadiazole derivatives were investigated.