We report the synthesis and characterization of three novel azobenzene-containing miktoarm star polymers AB₃ (M_n = 14 800, Đ_M = 1.22, M_n = 17 400, Đ_M = 1.10 and M_n = 26 200, Đ_M = 1.12) as well as their self-assembly properties in water. The three polymers are composed of an azopolymer and three identical arms of poly(N,N-diethylacrylamide) (PDEAA), featuring thermo-responsive properties. By carefully selecting the polymerization degree of PDEAA, and consequently the hydrophobic/hydrophilic ratio, a specific miktoarm polymer has been identified that forms stable micelles in water as is clearly revealed by Transmission Electron Microscopy (TEM). In addition, the thermo- and photo-responsive properties of the polymeric micelles in water were investigated. Encapsulation of Nile Red was probed via fluorescence spectroscopy as well as its release from the loaded probes triggered by UV irradiation, which causes a trans-to-cis isomerisation of the azobenzene moieties.

We report on the synthesis and characterization of new amphiphilic linear-dendritic block copolymers (LDBCs) as well as their self-assembly in water to form polymeric vesicles. We have also investigated the encapsulation of both hydrophilic and hydrophobic fluorescent probes by these stimuli-responsive polymeric vesicles and the use of light as an external stimulus to trigger the release of the probes. The LDBCs are composed of a 2000 g mol⁻¹ poly(ethylene glycol) (PEG) linear segment linked to a fourth generation 2,2-di(hydroxymethyl)propionic acid (bis-MPA) based dendron with 4-isobutyloxyazobenzene units at the periphery. By tuning the chemical structure of the azobenzene moieties, a specific LDBC has been identified that forms stable vesicles in water as it is clearly revealed by TEM and Cryo-TEM images. Encapsulation of both hydrophobic and hydrophilic molecules by these vesicular self-assemblies has been investigated by fluorescence analysis as well as the release of the loaded probes triggered by low intensity UV illumination, which is related to trans-to-cis isomerisation of the azobenzene moieties. Thus, the potential of these photo-responsive vesicles as light-responsive nanocarriers is demonstrated.

We assess the assembly of supramolecular complexes by hydrogen bonding between azocompounds and a diacylaminopyridine monomer by temperature-dependent Fourier transform infrared spectroscopy (FT-IR) and density functional theory (DFT) calculations. The electronic delocalisation in the supramolecular rings formed by multiple hydrogen bonds stabilises the complexes, which coexist with dimeric species in temperature-dependent equilibria. We show how the application of readily available molecular modelling and spectroscopic techniques can predict the stability of new supramolecular entities coexisting in equilibria, ultimately assessing the success of molecular recognition.