Carlos M. R. Abreu

Bacterial surface contamination is a significant public health concern, particularly for immunocompromised individuals, and has driven the development of self-sanitizing materials. Photodynamic inactivation (PDI)has emerged as a sustainable antimicrobial strategy that uses photosensitizers (PS) upon light activation. In this study, a porphyrin-functionalized xanthate was synthesized and used as a chain transfer agent in the MADIX polymerization of poly(vinyl chloride) (PVC) under environmentally friendly conditions. PVCs functionalized with porphyrin and having varied molecular weights were fully characterized by MALDI-TOF-MS, 1H NMR, SEC, DSC, and TGA to determine their composition, molecular weight, dispersity (Đ), and thermal properties. The obtained polymers were applied as antimicrobial coatings on glass substrates pretreated with a PVC-co-poly(butyl acrylate) (PBA) film-forming layer, and their surface morphology was analyzed by SEM. The antimicrobial performance against representative Gram-positive and Gram-negative strains, Staphylococcus aureus and Escherichia coli, respectively, was assessed under three conditions: dark, blue light (BL), and white light (WL). BL exposure produced the most pronounced cellular effects, resulting in a significant reduction in bacterial viability. These effects were further confirmed by SEM analysis, which showed visible structural damage to the bacterial cells. Cytocompatibility was confirmed using normal human dermal fibroblast (NHDF) cells. The PS polymer coatings (0.09 mg/cm2) demonstrated strong antimicrobial activity under light exposure and low cytotoxicity, highlighting their potential as photoactive antimicrobial surfaces for biomedical and hygiene-sensitive applications.

Dye-sensitized solar cells (DSSCs) have recently entered the market for indoor photovoltaics. Fast electron injection from dye to titania, the lifetime of the excited dye, and the suppression of back electron recombination at the photoanode/electrolyte interface are crucial for a high photocurrent conversion efficiency (PCE). This study presents block copolymers of poly(4-vinylpyridine) and poly(styrene)-P4VP₆₇-b-PSt _x (x=23;61) as efficient accelerators of electron injection from dye to titania with extended lifetime excited states and long-lasting back electron recombination suppression. P4VP₆₇-b-PSt₂₃ and P4VP₆₇-b-PSt₆₁ rendered devices with PCEs of 10.0 and 9.8%, respectively, under AM 1.5G light; PCEs of 19.4 and 16.4% under 1000 lx LED light were attained. Copolymers provided a stable PCE with the two most popular I₃ ^-/3I^- electrolytes based on ACN and 3-methoxypropionitrile solvents; PCE history was tracked in the dark and under 1000 h of continuous light soaking with passive load according to ISOS-D1 and ISOS-L2 aging protocols, respectively. The impact of the polymer molecular structure on electron recombination, charge injection, dye anchoring, light absorption, photocurrent generation, and PCE and the long-term history of photovoltaic metrics are discussed.

Synthesis of block copolymers (BCPs) by catalytic halogen exchange (cHE) is reported, using supplemental activator and reducing agent Atom Transfer Radical Polymerization (SARA ATRP). The cHE mechanism is based on the use of a small amount of a copper catalyst in the presence of a suitable excess of halide ions, for the synthesis of block copolymers from macroinitiators with monomers of mismatching reactivity. cHE overcomes the problem of inefficient initiation in block copolymerizations in which the second monomer provides dormant species that are more reactive than the initiator. Model macroinitiators with low dispersity are prepared and extended to afford well‐defined block copolymers of various compositions. Combined cHE/SARA ATRP is therefore a simple and potent polymerization tool for the copolymerization of a wide range of monomers allowing the production of tailored block copolymers.

The stringent control over the polymerization of less activated monomers remains one major challenge for Reversible Deactivation Radical Polymerizations (RDRP), including Atom Transfer Radical Polymerization (ATRP). Electrochemically mediated ATRP (eATRP) of a gaseous monomer, vinyl chloride (VC), was successfully achieved for the first time using a stainless-steel 304 (SS304) electrochemical reactor equipped with a simplified electrochemical setup. Controlled polymerizations were confirmed by the good agreement between theoretical and measured molecular weights, as well as the relatively narrow molecular weight distributions. Preservation of chain-end fidelity was verified by chain extension experiments, yielding poly(vinyl chloride) (PVC) homopolymers, block and statistical copolymers. The possibility of synthesizing PVC by eATRP is a promising alternative to afford cleaner (co)polymers, with low catalyst concentration. The metal body of the reactor was also successfully used as a cathode. The setup proposed in this contribution opens an avenue for the polymerization of other gaseous monomers.

Thiourea dioxide, a green and inexpensive compound used at industrial scale, was employed as reducing agent for the controlled polymerization of a wide range of monomer families, namely, acrylates (methyl acrylate, 2-hydroxyethyl acrylate, butyl acrylate, methacrylates (2-(dimethylamino)ethyl methacrylate, 2-aminoethyl methacrylate hydrochloride, and methyl methacrylate), styrene, acrylonitrile, and vinyl chloride (nonactivated monomer) by ATRP. Mechanistic studies confirmed that the polymerizations are ruled by the activators regenerated by electron transfer (ARGET) mechanism. It is worth noting that vinyl chloride has never been polymerized by ARGET ATRP. The system proved to be very versatile and robust, working in organic solvents, organic/water mixtures, and aqueous medium at near room temperature with low metal catalyst concentration. Chain extension experiments confirmed the high chain-end functionality of the polymers, allowing the preparation of several well-defined block copolymers.