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ABSTRACT: A photoinduced electron transfer‐reversible addition‐fragmentation chain transfer (PET‐RAFT) polymerization of p‐methylstyrene (p‐MS) and styrene (St) with 2‐(dodecylthiocarbonothioylthio)‐2‐methylpropionic acid as the chain transfer agent (CTA) and aromatic aldehydes, including 4‐cyanobenzaldehyde (PC1), 2,4‐dimethoxy benzaldehyde, and 4‐methoxy benzaldehyde, as organic photocatalysts has been demonstrated via irradiation with 23 W compact fluorescent lamps. The kinetics of the polymerizations shows first order with respect to monomer conversions. Linear evolution of the Mn of the produced polymers with the monomer conversion is observed. Meanwhile, the as‐prepared polymers are of relatively narrow polydispersity (PDI = Mw/Mn). For instance, the polymerization of p‐MS shows living polymerization features using PC1 within a range of solvents. Especially, the Mn of PpMS increased from about 2100 to 12,700 g/mol with the monomer conversion from 8% to 52% in tetrahydrofuran. The controlled polymerization of St is also observed under optimal reaction conditions. However, the Mn discrepancy between the experimental readings and theoretical calculations is greater at the monomer conversions greater than 40% and the PDI increased gradually over the monomer conversion. This is probably because that CTA is strongly sensitive to the light irradiation with wave range around its characteristic absorption wavelength, leading to significant decomposition of CTA moieties during the RAFT polymerization. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 2072–2079 [ABSTRACT FROM AUTHOR]

ABSTRACT The benzaldehyde derivatives, such as 2,4-dimethoxy benzaldehyde (PC1) and p-anisaldehyde (PC2), were successfully used as photoredox catalysts (PCs) in combination with typical RAFT agent 4-cyano-4-(phenylcarbonothioylthio)pentanoic acid (CTP) for the controlled photoinduced electron transfer RAFT polymerization (PET-RAFT) of methyl methacrylate (MMA) and benzyl methacrylate (BnMA) at room temperature. The kinetics of the polymerizations showed first order with respect to monomer conversions. Besides, the average number molecular weights ( Mn) of the produced polymers increased linearly with the monomer conversions and kept relatively narrow polydispersity (PDI = Mw /Mn). For example, the Mn of PMMA increased from about 3400 to 17,300 g mol−1 with the increasing in monomer conversion from 11% to 85%, and the PDI maintained around 1.36. The living features of polymerizations with the PC1 and PC2 as catalysts have also been further supported by chain extension and synthesis of PMMA- b-PBnMA diblock copolymer. As a result, the simplicity and efficiency of benzaldehyde derivatives catalyzed PET-RAFT polymerization have been demonstrated under mild conditions. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 229-236 [ABSTRACT FROM AUTHOR]

ABSTRACT A new polymer chain growth mode, having multiple potential chain propagation sites, initiated by oligomer of α-methylstyrene (AMS) and styrene (St) (PAS) is presented in this article. The effects of PAS content, AMS fraction in PAS and reaction temperature on bulk polymerization of St have been investigated. It is demonstrated that the PAS performed as macroinitiator in the polymerization of St. The average molecular weights of products increase significantly with the evolution of the polymerization, which is different from conventional free radical polymerization. With 20 wt % macroinitiator, the molecular weights increase from 1.21 × 105 to 3.00 × 105 with the monomer conversion increasing from 15.3 to 83.0%. This unique feature is tentatively attributed to both the reversible polymerization-depolymerization of AMS segments at high temperature which could generate more than one propagation sites in a polymer chain and the combination termination of St free radical polymerization. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41460. [ABSTRACT FROM AUTHOR]

Organotellurium compounds-mediated living radical polymerization (TERP) is one of the most robust tools of living free radical polymerizations (LRP). However, synthesis and purification of organotellurium compounds are time-consuming and to be operated in an inert atmosphere due to their extreme sensitivity to trace oxygen. In this article, a simple process of TERP, operating in open air, has been reported. It has demonstrated that the crude organotellurium compound, ethyl 2-phenyltellanyl-2-methylpropionate, could mediate 2,2′-azobis (isobutyronitrile) initiated styrene (St) and butyl acrylate (BA) polymerization as an LRP system. For the bulk and solution polymerization of St and the solution polymerization of BA, the molecular weights of produced polymers increased linearly with the monomer conversions. During the same time, the molecular weight distributions kept under 1.3. The UV-vis spectrum showed that the PS polymer chain bearing C-TePh end group. With the sequential monomer addition technique, a clean diblock polymer of PS- b-PBA was also obtained. [ABSTRACT FROM AUTHOR]

With fac-Ir(ppy)3 as photoredox catalyst and ethyl 2-bromoisobutyrate (EBiB) as initiator, the homopolymerization of methyl methacrylate (MMA) in different solvents, such as N, N-dimethylformamide (DMF), acetonitrile, and anisole are run under irradiation of an LED lamp. The results show that anisole is a better solvent for the polymerization with regard to the polydispersity index (PDI). A well-controlled polymerization of poly(ethylene glycol) methyl ether methacrylate (PEGMA) is demonstrated and the clean block copolymer of PMMA- b-PPEGMA is prepared with PDI less than 1.3; however, the 2-(dimethylamino) ethyl methacrylate (DMAEMA) polymerization is poorly controlled. With the PMMA as macromolecular initiator, the block copolymer PMMA- b-PDMAEMA can be prepared with PDI around 2.0. [ABSTRACT FROM AUTHOR]

ABSTRACT The hydrophobic solid surface modification with fluorine-containing monomers has received tremendous attention because of its unique structure and excellent property. However, these hydrophobic films normally suffer from two major problems: one is weak interface interaction between fluoropolymers and substrates, and the other is the high cost of fluorine-containing monomers. Herein, with the aim of feasible industrial application, a facile in situ UV photo-grafting method is reported, which could ensure the formation of chemical bonds between fluoropolymer-grafted layer and substrate with a low cost commercial 2,2,2-trifluoroethyl methacrylate (TFEMA) as monomer. With low-density polyethylene (LDPE) film as a model substrate, four kinds of poly-TFEMA-grafted layer are fabricated on LDPE films with different surface morphologies: polymer brush, polymer network, crosslinked nanoparticles, and a micro- and nanoscale hierarchical structure. The experimental results showed that the water contact angles (CAs) of the LDPE films grafted with polymer brush, polymer network, and crosslinked nanoparticles were (103 ± 2)°, (95 ± 2)°, and (122 ± 2)°, respectively, which were much higher than that of LDPE film. The introduction of micro- and nanoscale hierarchical structures can dramatically improve the surface roughness, which will further enhance the film hydrophobicity, and the water CA can reach as high as (140 ± 1)°. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 1059-1067 [ABSTRACT FROM AUTHOR]

Visible-light-induced free radical polymerization of methyl methacrylate (MMA) and 1,1,1-trifluoroethyl methacrylate (TFEMA) with a difunctional initiator, dimethyl 2,6-dibromoheptanedioate (DMDBHD), conjugated with a photoredox catalyst, tris(2-phenylpyridinato)iridium(III) ( fac-[Ir(ppy)3]), is investigated. Kinetic studies demonstrate that homopolymerizations of both MMA and TFEMA are controlled radical polymerizations. The linear increase of molecular weights with monomer conversion and the narrow PDIs (1.2-1.4) reveal a good living character. In addition, PTFEMA- b-PMMA- b-PTFEMA triblock copolymer is prepared by a one-pot process with sequential monomer addition. The [ABSTRACT FROM AUTHOR]