Thermosensitive ABC triblock copolymers with different block lengths and block orders were prepared by reversible addition− fragmentation chain transfer (RAFT) polymerization. Using a nonionic macro-RAFT agent containing poly(ethylene oxide) (PEO, average degree of polymerization 17), either N-acryloylglycinamide (NAGA) or N-isopropylacrylamide (NIPAM) was first polymerized to diblock copolymers. The diblock copolymers exhibited typical thermoresponsive character of PNAGA and PNIPAM in aqueous solutions. Chain extension of the diblock copolymers was then made to prepare PEO-b-PNAGA-b-PNIPAM and PEO-b-PNIPAM-b-PNAGA triblock copolymers. Investigations of the polymer solutions showed that the triblock copolymers exhibited both UCST and LCST type transitions. The phase transitions induced the formation of polymer aggregates below UCST and above LCST, and the aggregate structures were inverted upon heating and cooling. The order of the polymer blocks with respect to PEO as well as the block sizes contributed to the thermal response.

Nanoparticles with structural or chemical anisotropy are promising materials in domains as diverse as cellular delivery, photonic materials, or interfacial engineering. The surface chemistry may play a major role in some of these contexts. Introducing reactivity into such polymeric nanomaterials is thus of great potential, yet is still a concept in its infancy. In the current contribution, a simple nanoprecipitation technique leads to nanoparticles with diameters as low as 150 nm and well-defined reactive surface patches of less than 30 nm in width, as well as surface-reactive flat, disc-like nanoparticles with corresponding dimensions, via an additional crosslinking/delamination sequence. To this aim, chemically doped block copolymers (BCPs) are employed. Control over morphology is attained by tuning preparation conditions, such as polymer concentration, solvent mixture composition, and blending with non-functional BCP. Surface reactivity is demonstrated using a modular ligation method for the site-selective immobilization of thiol molecules. The current approach constitutes a straightforward methodology requiring minimal engineering to produce nanoparticles with confined surface reactivity and/or shape anisotropy.

The suitability of pentafluorophenyl (PFP) esters and PFP alkyl moieties for orthogonal dual functionalization of block copolymer segments is evaluated. While amidation followed by para-fluoro–thiol substitution is a viable reaction sequence, thiol-based substitution can occur on PFP esters at a high rate, thereby hampering the viability of the reverse sequence.