A photoinduced reversible addition-fragmentation chain-transfer (photo-RAFT) polymerization technique in the presence of sodium pyruvate (SP) and pyruvic acid derivatives was developed. Depending on the wavelength of light used, SP acted as a biocompatible photoinitiator or promoter for polymerization, allowing rapid open-to-air polymerization in aqueous media. Under UV irradiation (370 nm), SP decomposes to generate CO₂ and radicals, initiating polymerization. Under blue (450 nm) or green (525 nm) irradiation, SP enhances the polymerization rate via interaction with the excited state RAFT agent. This method enabled the polymerization of a range of hydrophilic monomers in reaction volumes up to 250 mL, eliminating the need to remove radical inhibitors from the monomers. In addition, photo-RAFT polymerization using SP allowed for the facile synthesis of protein–polymer hybrids in short reaction times (<1 h), low organic content (≤16%), and without rigorous deoxygenation and the use of transition metal photocatalysts. Enzymatic studies of a model protein (chymotrypsin) showed that despite a significant loss of protein activity after conjugation with RAFT chain transfer agents, the grafting polymers from proteins resulted in a 3–4-fold recovery of protein activity.

In this study, a high-pressure-assisted photoinduced atom transfer radical polymerization (p ≤ 250 MPa) enabled the synthesis of ultra-high-molecular-weight polymers (UHMWPs) of up to 9 350 000 and low/moderate dispersity (1.10 < Đ < 1.46) in a co-solvent system (water/DMSO), without reaction mixture deoxygenation.

The innovative combination of light and high pressure allowed us to effectively polymerize for the first time challenging ionic 1,2,4-triazolium-based ionic liquids (ILs) with fluorinate anions (MetTRI/NTF) and non-ionic vinyl acetate (VAc), both classified as less-activated monomers (LAMs). Three different synthetic photo-induced protocols comprising controlled metal-free organocatalyzed Atom Transfer Radical Polymerization (O-ATRP), chain transfer to solvent free-radical polymerization (CT-FRP), and classical free-radical polymerization (FRP) were investigated. As a result, well-defined polymers with a wide range of molecular weights M_n and different concentrations of OH domains incorporated into their polymer backbones in a very short time frame (5–120 min) were produced. Having a series of 1,2,4-triazolium-based poly(ionic liquid)s (PILs), a unique opportunity appeared to study the relationship between their molecular weights, glass transition temperature, and dc conductivity, undoubtedly enriching the library of tailored PILs of enhanced conductivity, a critical parameter determining their serviceability.

This work highlights the development of a robust and universal route towards gaining control over macromolecule molecular weight, molecular weight distribution and, more importantly, morphology through the implementation of photoiniferter-mediated RAFT (photo-RAFT) carried out using mesoporous materials varying in the composition, pore arrangement, and pore diameters (metal–organic framework SBA-15 powder d = 5–15 nm, silica SiO₂ templates d = 4 nm, alumina oxide AAO templates d = 10 nm). In fact, the application of these matrices that can act as nanoreactors for in situ UV-irradiated photo-RAFT of both commercial methyl methacrylate (more-activated monomer) and the synthesized N-vinyl-1,2,4-triazolium-based ionic liquid (less-activated monomer) is a key aspect of our approach. The collected data allowed us to probe the influence of the structural features of nanoreactors (i.e., transparency, porosity, roughness, and acidity) as well as confinement-related effects connected to variation in free volume and surface interactions on the polymerization path and properties of the produced ionic and non-ionic polymers. It was found that the application of all tested nanoreactors ensures greater control over photo-RAFT than analogous batch systems (macroscale photo-RAFT). However, running the reaction in mesoporous AAO templates offered by far the best control over the course of photo-RAFT of both the less-activated monomer (LAM) and the more-activated monomer (MAM) irrespective of the type of selected RAFT agent (switchable) (carbamodithioate vs. trithiocarbonate), their properties and, more importantly, the yield of the recovered polymers.

Well-defined poly(γ-butyrolactone) was synthesized with great efficiency via high pressure assisted cationic ROP of hardly polimerizable γ-butyrolactone.