Franck D'AGosto

A versatile and flexible azlactone clickable hyperbranched polymer (HBP) platform was prepared by reversible addition–fragmentation chain transfer self-condensing vinyl polymerization (RAFT-SCVP) followed by postpolymerization modifications (PPMs). RAFT-SCVP of a thiocarbonylthio methacrylic-based transmer and 2-(N,N-dimethylamino)ethyl methacrylate (DMAEMA) resulted in HBP-PDMAEMA, whose branched topology was thoroughly characterized using proton nuclear magnetic resonance (1H NMR) spectroscopy, size exclusion chromatography (SEC) with multiangle light scattering, and viscometry detections. The HBP structure can be tailored through adjustment of the initial DMAEMA/transmer molar ratio: changing the initial molar ratio of DMAEMA/transmer from 10/1 to 1/1 results in an increase in the degree of branching (DB) from 0.08 to 0.22. Successive PPMs of these thiocarbonylthio-functionalized scaffolds were carried out to produce a versatile hyperbranched clickable platform containing azlactone terminal groups, as demonstrated by SEC using ultraviolet–visible (UV–vis) detection and Fourier transform infrared (FTIR) analyses. The efficiency of the aminolysis of thiocarbonylthio groups seems to be governed by their intrinsic reactivity, which depends on their structural environment. Either thiocarbonylthio groups participate in a chain transfer reaction and create branching points or they are not involved in the chain transfer reaction and remain as pendant groups. The efficient azlactone-amine click reaction of azlactone-functionalized HBP with various amines enables the elaboration of HBP with multiple functional terminal groups.

Low weight, low price, and excellent long-term stability are the main advantages of vinyl-based polymers. Such polymers are obtained by chain-growth processes leading to all-carbon backbones, which are non­(bio)­degradable and nonchemically recyclable. Unfortunately, this chemical stability manifests as postuse persistence; coupled with poor waste management practices, polymers including vinyl derivatives pose major environmental problems today. Given that it is very difficult and costly to design entirely new materials that have both desired properties (mechanical, thermal, solvent resistance, etc.) and recyclability and/or biodegradability at the end of their life cycle, it seems worthwhile to transform already known materials into (bio)­degradable/chemically recyclable equivalents. One approach is based on the introduction of cleavable bonds into the polymer backbone, so that degradation (by hydrolysis, for example) produces oligomers which can then be further recycled and/or bioassimilated by micro-organisms. An effective method for incorporating weak bonds randomly into the C–C backbone of a vinyl polymer is the copolymerization of vinyl monomers with cyclic monomers by radical ring-opening polymerization (rROP). This method combines the advantages of ring-opening and radical polymerization, i.e., the production of polymers with heteroatoms and/or functional groups in the main chain, with the robustness, ease of use, and mild polymerization conditions of a radical process. The aim of this tutorial review is to provide polymer chemists with guidelines to use rROP to prepare vinyl-based materials with predictable degradation. This review thus presents the rROP principle, the main families of cyclic monomers copolymerizable with vinyl monomers, and the main applications of the resulting (bio)­degradable/chemically recyclable materials (polymers for packaging, latexes and degradable surfaces, 3D printing, biomaterials and water-soluble polymers).

Controlled coordination polymerization of olefins and 1,3-dienes enables macromolecular engineering and, in particular, the design of new thermoplastic elastomers with high mechanical properties.

Olefin triblock copolymers based on glassy polystyrene (PS), ethylene butadiene rubber (EBR) and highly crystalline polyethylene (PE) segments were prepared for the first time using a switch strategy from anionic polymerization to coordinative chain transfer (co)polymerization (CCT(co)P). PS chains obtained by anionic polymerization were transmetalated with mesitylmagnesium bromide (BrMgMes) to act as macromolecular chain transfer agents (macro‐CTA, PS‐MgMes) in the CCTcoP of ethylene and butadiene using {Me₂Si(C₁₃H₈)₂Nd(BH₄)₂Li(THF)}₂ complex (1). Further chain extension by CCTP using pure ethylene in the monomer feed afforded well‐defined PS‐b‐EBR‐b‐PE triblock copolymers. The structural, rheological and mechanical properties of these materials demonstrate excellent balance between properties and easy processability at moderate temperatures (>150 °C). We demonstrate that such triblock copolymers behave effectively as low‐viscosity PS‐b‐EBR diblock copolymers above the melting point of PE domains and high performance thermoplastic elastomers (TPEs) upon crystallization of PE segments.

Olefin triblock copolymers based on glassy polystyrene (PS), ethylene butadiene rubber (EBR) and highly crystalline polyethylene (PE) segments were prepared for the first time using a switch strategy from anionic polymerization to coordinative chain transfer (co)polymerization (CCT(co)P). PS chains obtained by anionic polymerization were transmetalated with mesitylmagnesium bromide (BrMgMes) to act as macromolecular chain transfer agents (macro‐CTA, PS‐MgMes) in the CCTcoP of ethylene and butadiene using {Me₂Si(C₁₃H₈)₂Nd(BH₄)₂Li(THF)}₂ complex (1). Further chain extension by CCTP using pure ethylene in the monomer feed afforded well‐defined PS‐b‐EBR‐b‐PE triblock copolymers. The structural, rheological and mechanical properties of these materials demonstrate excellent balance between properties and easy processability at moderate temperatures (>150 °C). We demonstrate that such triblock copolymers behave effectively as low‐viscosity PS‐b‐EBR diblock copolymers above the melting point of PE domains and high performance thermoplastic elastomers (TPEs) upon crystallization of PE segments.

ZnEt ₂ is used for the first time as a reversible transfer agent in olefin polymerization with a neodymium metallocene catalyst. Its presence has improved the catalyst's performance for the coordinative chain transfer polymerization of ethylene.

In this study, evaporation-induced size segregation and interparticle interactions are harnessed to tune the microstructure of photocatalytic colloidal coatings containing TiO₂ nanoparticles and polymer particles. This enabled the fabrication of a library of five distinct microstructures: TiO₂-on-top stratification, a thin top layer of polymer or TiO₂, homogeneous films of raspberry particles, and a sandwich structure. The photocatalytic and antibacterial activities of the coatings were evaluated by testing the viability of Methicillin-resistant Staphylococcus aureus (MRSA) bacteria using the ISO-27447 protocol, showing a strong correlation with the microstructure. UVA irradiation for 4 h induces a reduction in MRSA viability in all coating systems, ranging from 0.6 to 1.1 log. Films with TiO₂-enriched top surfaces exhibit better resistance to prolonged exposure to disinfection and bacterial testing. The remaining systems, nonetheless, present higher antibacterial activity because of a larger number of pores and coating defects that enhance light and water accessibility for the generation and transport of reactive oxygen species. This work establishes design rules for photocatalytic coatings based on the interplay between performance and film architecture, offering valuable insights for several applications, including antibacterial surfaces, self-cleaning/antifogging applications, and water purification.