Thermostimulable Wax@SiO2 Core-Shell Particles

We propose a new synthesis pathway without any sacrificial template to prepare original monodisperse thermo-7 responsive capsules made of a wax core surrounded by a silica shell. Under heating, the inner wax expands and the shell 8 breaks, leading to the liquid oil release. Such capsules that allow triggered deliverance provoked by an external stimulus 9 belong to the class of smart materials. The process is based on the elaboration of size-controlled emulsions stabilized by 10 particles (Pickering emulsions) exploiting the limited coalescence phenomenon. Then the emulsions are cooled down 11 and the obtained suspensions are mineralized by the hydrolysis and condensation of a monomer at the wax-water 12 interface, leading to the formation of capsules. The shell break and the liquid oil release are provoked by heating above 13 the wax melting temperature. We characterize the obtained materials and examine the effect of processing parameters 14 and heating history. By an appropriate choice of the wax, the temperature of release can easily be tuned

Biodegradable star polymers functionalized with beta-cyclodextrin inclusion complexes

Three-armed biodegradable star polymers made from polystyrene (polySt) and poly (polyethylene glycol) acrylate (polyPEG-A) were synthesized via a "core first" methodology using a trifunctional RAFT agent, created by attaching RAFT agents to a core via their R-groups. The resultant three-armed polymeric structures were well-defined, with polydispersity indices less than 1.2. Upon aminolysis and further reaction with dithiodipyridine (DTDP), these three-armed polymers could be tailored with sulfhydryl and pyridyldisulfide (PDS) end functionalities, available for further reaction with any free-sulfhydryl group containing precursors to form disulfide linkages. Nuclear magnetic resonance (NMR) confirmed that more than 98% of the polymer arms retained integral trithiocarbonate active sites after polymerization. Intradisulfide linkages between the core and the arms conferred biodegradability on the star architectures. Subsequently, the arm-termini were attached to cholesterol also via disulfide linkages. The cholesterol terminated arms were then used to form supramolecular structures via inclusion complex formation with beta-cyclodextrin (beta-CD). The star architectures were found to degrade rapidly on treatment with DL-dithiothereitol (DTT). The star polymers and supramolecular structures were characterized using gel permation chromatography (GPC), static light scattering (SLS), 2D NMR, and fluorescence spectroscopy