Synthesis and characterization of well-defined end-chain functional macrophotoinitiators of polystyrene and polyacrylonitrile by RAFT/MADIX polymerization

• Published in: European polymer journal Vol. 119; pp. 102 - 113
• Main Authors: Uyar, Zafer, Turgut, Ferhat, Arslan, Ulku, Durgun, Mustafa, Degirmenci, Mustafa
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.10.2019; Elsevier BV
• Subjects: Benzoin; Benzyl bromide; Block copolymer; Block copolymers; Cationic polymerization; Chain transfer; Chemical analysis; Chemical synthesis; Copolymers; Cyclohexene; Free radical polymerization; Free radicals; Functional groups; Infrared spectroscopy; Macrophotoinitiator; Monomers; NMR spectroscopy; Photoinitiated polymerization; Polyacrylonitrile; Polyimide resins; Polymerization; Polymethyl methacrylate; Polystyrene; Polystyrene resins; Prepolymers; RAFT/MADIX polymerization; Styrenes; Vinyl acetate; Xanthate; Polyacrylonitrile; Macrophotoinitiator; Photoinitiated polymerization; Xanthate; RAFT/MADIX polymerization; Polystyrene; Block copolymer
• ISSN: 0014-3057; 1873-1945
• DOI: 10.1016/j.eurpolymj.2019.07.028

[Display omitted] •A novel photoreactive chain transfer agent for RAFT/MADIX polymerization.•Well-defined macrophotoinitiators of PSt and PAN via RAFT/MADIX polymerization.•Diblock copolymers by photoinitiated free radical promoted cationic polymerization. An alternative approach for the synthesis of well-defined macrophotoinitiators of polystyrene and polyacrylonitrile with an end-chain photofunctional group via reversible addition-fragmentation chain transfer/macromolecular design via the interchange of xanthate (RAFT/MADIX) polymerization has been described. For this purpose, a novel photoreactive chain transfer agent (CTA-PI), namely S-benzyl O-(2-oxo-1,2-diphenylethyl) carbonodithioate, was prepared with an efficient one-pot, two-step synthesis by first reacting benzoin photoinitiator (PI) with CS2 in the presence of NaH and then reacting this intermediate with benzyl bromide in THF. The structure of CTA-PI was determined by FT-IR, 1H NMR, and 13C NMR spectroscopy and confirmed by elemental analysis. Here, we used this xanthate based CTA in conjunction with 4,4′-azobis(4-cyanovaleric acid) (ACVA), as the initiating species, to investigate RAFT/MADIX polymerization of styrene (St), acrylonitrile (AN), methyl methacrylate (MMA), the so-called more activated monomers (MAMs), and vinyl acetate (VAc), one of the less activated monomers (LAMs). While RAFT/MADIX polymerization of styrene and acrylonitrile progressed in a controlled manner producing well-defined macrophotoinitiators with benzoin end-chain functional group, polymerization of methyl methacrylate proceeded uncontrollably. Polymerization of vinyl acetate under the same reaction conditions, on the other hand, did not occur at all. Spectroscopic and GPC measurements indicated that syntheses of polystyrene and polyacrylonitrile macrophotoinitiators bearing a photoreactive benzoin end group, PSt-PI and PAN-PI, respectively, with well-defined structures were achieved. These unique macrophotoinitiators were then used as prepolymers in photoinitiated free radical promoted cationic polymerization of cyclohexene oxide (CHO) and butyl vinyl ether (BVE) monomers to obtain PSt-PCHO, PSt-PBVE, PAN-PCHO, and PAN-PBVE di-block copolymers.