Polymer Nanocomposites via Click Chemistry Reactions

The emerging areas of polymer nanocomposites, as some are already in use in industrial applications and daily commodities, have the potential of offering new technologies with all manner of prominent capabilities. The incorporation of nanomaterials into polymeric matrix provides significant improvements, such as higher mechanical, thermal or electrical properties. In these materials, interface/interphase of components play a crucial role bringing additional features on the resulting nanocomposites. Among the various preparation strategies of such materials, an appealing strategy relies on the use of click chemistry concept as a multi-purpose toolbox for both fabrication and modulation of the material characteristics. This review aims to deliver new insights to the researchers of the field by noticing effective click chemistry-based methodologies on the preparation of polymer nanocomposites and their key applications such as optic, biomedical, coatings and sensor

Synthesis and characterization of polypropylene-graft-poly(l-lactide) copolymers by CuAAC click chemistry

Altinkok, Cagatay (Trakya author)The syntheses of polypropylene-graft-poly(l-lactide) copolymers (PP-g-PLAs) via copper (I)-catalyzed azide-alkyne cycloaddition "click" reaction (CuAAC) using azide side-chain functionalized polypropylene (PP-N-3) and alkyne end-functionalized poly(l-lactide) (PLA-Alkyne) were reported. The CuAAC was then applied to azide and different feeding ratios of alkyne functional polymers to give PP-g-PLAs that were characterized by FTIR, H-1-NMR, GPC, DSC, and WCA measurements. The CuAAC click reaction was achieved by two different feeding ratio (PP-N-3:PLA-Alkyne = 1:5 and 1:10) and thermal, biodegradable, and surface properties of obtained graft copolymers were investigated. The molar ratio of PLA were calculated as 72.7 (PP-g-PLA-1) and 78.4% (PP-g-PLA-2) by H-1-NMR spectroscopy. The water contact angle (WCA) values of PP-g-PLA-1 (81(o) +/- 1.3) and PP-g-PLA-2 (75(o) +/- 1.6) copolymers were compared with commercial chlorinated polypropylene (PP-Cl) (90(o) +/- 1.0), suggesting a more hydrophilic nature of desired graft copolymers produced. Conversely, the enzymatic biodegradation studies revealed that the weight losses of graft copolymers were determined as 13.6 and 22.1%, which is about 4% for commercial PP-Cl sample. Thus, it was clear that this simple and facile method was effective in promoting biodegradation of commercial polypropylene and attractive particularly for worldwide environmental remediation goals. (c) 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 2595-260

Synthesis of self-curable polysulfone containing pendant benzoxazine units via CuAAC click chemistry

<p>Synthesis, characterization, and properties of new thermally curable polysulfone containing benzoxazine moieties in the side chain were investigated. First, chloromethylation and subsequent azidation processes were performed to form polysulfone containing pendant clickable azide groups. Independently, antagonist 3,4-dihydro-3-(prop-2-ynyl)-2H-benzoxazine was prepared by using paraformaldehyde, phenol and propargylamine. The following copper(I) catalyzed azide-alkyne cycloaddition click reaction was applied to obtain self-curable polysulfone with pendant benzoxazine units. The polymer and intermediates at various stages were characterized by ¹H-NMR, ¹³C-NMR and FT-IR spectroscopies. The thermal properties and curing behavior of final polymer were investigated by differential scanning calorimetry and thermal gravimetric analysis. Compared to the neat polysulfone, the obtained polymers exhibited thermally more stable polymers.</p

Photoinduced reverse atom transfer radical polymerization of methyl methacrylate using camphorquinone/benzhydrol system

A versatile initiating system composed of camphorquinone/benzhydrol and (CuBr2)-Br-II/N,N,N ',N '',N ''-pentamethyldiethylenetriamine for photoinduced reverse atom transfer radical polymerization has been developed. The control experiments, where each component is eliminated in the reaction, serve as a direct verification of the mechanism. There is poor or no control over the polymerization of methyl methacrylate in the absence of either camphorquinone or benzhydrol. The experimental molecular weights are considerably higher than theoretical values and the obtained polymers show slightly broad molecular weight distributions ranging from 1.13 to 1.51 in the process. Although at relatively lower polymerization rates, the addition of an alkyl halide to the system leads to a better control of the polymerization as reflected by the improved molecular weight distribution and chain-end functionality. (c) 2013 Society of Chemical Industr

Synthesis of block copolymers by selective H-abstraction and radical coupling reactions using benzophenone/benzhydrol photoinitiating system

Block copolymers were synthesized by a simple photochemical strategy based on selective H-abstraction and radical coupling reactions of ketyl macroradicals. Benzophenone (BP) and benzhydrol (Bzh) end functional polymers were synthesized by atom transfer radical polymerization (ATRP) using functional initiators. Subsequently, the resulting end functional polymers were mixed in 1:1 M ratio and irradiated to form ketyl radicals by hydrogen abstraction of the excited BP moieties from Bzh moieties. The influence of various experimental parameters on the polymerization such as type of polymers and solvents were examined. H-1 NMR, UV and GPC measurements clearly pointed out an efficient photoinduced end coupling reaction between ketyl radicals. (C) 2014 Elsevier Ltd. All rights reserved

Photoinduced Free Radical Promoted Copper(I)-Catalyzed Click Chemistry for Macromolecular Syntheses

Photoinduced copper­(I)-catalyzed Huisgen 1,3-dipolar cycloaddition (CuAAC) via photoinduced electron transfer using free radical photoinitiators has been developed as a new platform to serve as orthogonal click system. Photoinitiators acting at near UV and visible range, namely 2, 2-dimethoxy-2-phenyl acetophenone, 2-benzyl-2-dimethylamino-4′-morpholino butyrophenone, 2,4,6-trimethylbenzoyl)­diphenylphosphine oxide, dicyclopentadienyl bis­[2,6-difluoro-3-(1-pyrrolyl)­phenyl] titanium) and camphorquinone/benzyl alcohol were tested with copper­(II) chloride/<i>N</i>,<i>N</i>,<i>N</i>′,<i>N</i>″,<i>N</i>″-pentamethyldiethylenetriamine complex to catalyze the CuAAC via photoinduced electron transfer reaction. This strategy has been applied in construction of various macromolecular architectures including telechelic polymers and block copolymers. Spectroscopic and chromatographic investigations revealed that successful macromolecular syntheses have been achieved by this technique

Visible Light-Induced Atom Transfer Radical Polymerization for Macromolecular Syntheses

Visible light-induced atom transfer radical polymerization (ATRP) of vinyl monomers are examined by using various photocatalysts systems including Type I and Type II photoinitiators, dyes, dimanganese decacarbonyl and semiconducting photocatalysts. The influence of various experimental parameters on the polymerization such as type of light sources and photocatalyts, and concentration of metal catalysts are also investigated. Although there currently exist only a few examples, the visible light initiation can be applied to the ATRP process providing a mild and efficient method for the in situ generation of Cu(I) activator