Development of a sustainable route for the synthesis of star-shaped poly(ε-caprolactone) using renewable feedstocks in clean solvents (scCO₂ and bulk) with the catalysts Sn(Oct)₂ or the enzyme Novozym 435.

A series of amphiphilic photo-responsive heterografted copolymers have been successfully synthesized. The random copolymers were composed of a methacrylate backbone, with various compositions of hydrophilic oligomeric 2-methyl-2-oxazoline side chains (OMOx) and hydrophobic long alkyl chains terminated by a coumarin moiety (Cm). Using dynamic (DLS) and static light scattering (SLS), and transmission electron microscopy (TEM), their self-assembling behavior was studied in water using the nanoprecipitation method. Depending on the system, one, two or three particle size distributions co-exist in solution. However, DLS measurements showed that monomodal and slightly polydisperse self-assemblies were obtained with the more hydrophobic copolymers (i.e., 85% of hydrophobic monomers with a long alkyl chain terminated by a coumarin moiety (MCm) per molecule) with hydrodynamic diameters ranging from ca. 130 to 300 nm. Morphological information on these self-assembly structures was obtained using SLS: a Gaussian behavior has thus been evidenced. Finally, these heterografted copolymers were illuminated using UV light at λ = 350 nm inducing photo-crosslinking of the coumarin units. The influence of UV illumination on the thus-formed nanoparticles was investigated by carrying out complementarily DLS-measurements and UV spectroscopy.

Amphiphilic graft copolymers composed of a methacrylate-based hydrophobic backbone with C₁₁ pending chains end-capped by hydrophilic polyoxazoline (POx) blocks were successfully synthesized using the grafting-onto method by associating reverse addition fragmentation chain transfer (RAFT) polymerization with azide–alkyne Huisgen's cycloaddition (CuAAC). Pure and well-characterized copolymers with different molecular weights and without traces of starting polymers were obtained. The hydrophilic character of the copolymers was controlled by copolymerizing the azido-terminated monomer 11-azido-undecanoyl methacrylate (AzUMA) with lauryl methacrylate (LM), the corresponding (co)polymers being then coupled with α-alkyne-POx. Using dynamic light scattering (DLS) and transmission electronic microscopy (TEM) techniques, their self-assembling behavior was studied by direct dissolution in water without further filtration. Depending on the systems, two or three particle size distributions co-exist in solution. However, the smallest objects, with D_H-values around 6, 42 and 255 nm, were obtained with the most hydrophilic copolymers (∼90% of hydrophilic group per molecule). Moreover, the influence of the starting copolymer architecture on its self-organization behavior was emphasized by comparing the self-assembly of the graft copolymers with that of an amphiphilic macromonomer, in situ polymerized, and whose structure mimics that of the repeating unit of the graft copolymers.

Photo-active nanoparticles (NP_D, NP_T, NP_H) were elaborated in water from amphiphilic diblock (D), triblock (T) and heterograft (H) copolymers based on a chromatic unit, coumarin, linked to an alkyl chain and a hydrophilic polyoxazoline chain.