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41.
Nobuyuki Otozawa Rio Hamajima Masataka Yoshioka Raito Kato Arisa Tanaka Hiroto Fukuma Toshiki Terao Kei Manabe Syuji Fujii Yoshinobu Nakamura Atsushi Takahara Tomoyasu Hirai 《Journal of polymer science. Part A, Polymer chemistry》2020,58(14):1960-1964
This study investigates the effect of ionic liquids (ILs) on the anionic polymerization of methyl methacrylate (MMA). Polymethyl methacrylate (PMMA), an isotactic polymer, is prepared by anionic polymerization at a high reaction temperature with an IL that acts as both solvent and additive. The most plausible reaction mechanism is determined using 1H NMR and Fourier-transform infrared spectroscopy. The electrostatic interaction between MMA and the IL increases the apparent steric hindrance in MMA, resulting in the isotactic PMMA. 相似文献
42.
Claudia V. Lopez Menisha S. Karunarathna Moira K. Lauer Charini P. Maladeniya Timmy Thiounn Edward D. Ackley Rhett C. Smith 《Journal of polymer science. Part A, Polymer chemistry》2020,58(16):2259-2266
Here are reported composites made by crosslinking unsaturated units in canola, sunflower, or linseed oil with sulfur to yield CanS , SunS , and LinS , respectively. These plant oils were selected because the average number of crosslinkable unsaturated units per triglyceride vary from 1.3 for canola to 1.5 for sunflower and 1.8 for linseed oil. The remeltable composites show compressive strengths that increase with increasing unsaturation number from CanS (9.3 MPa) to SunS (17.9 MPa) to LinS (22.9 MPa). These values for SunS and LinS are competitive when compared with the value of 17 MPa required for residential building using traditional Portland cement. The plant oil composites are recyclable over many cycles and can retain up to 100% of strength after 24 hr in oxidizing acid under conditions where Portland cement is dissolved in under 30 min. Infusion of the composites into premade cement blocks affords them with significantly improved acid resistance as well. This work thus provides a simple, nearly 100% atom economical route to convert plant oils and waste sulfur to composites having enhanced performance over commercial structural materials. 相似文献
43.
Berran Sanay Bernd Strehmel Veronika Strehmel 《Journal of polymer science. Part A, Polymer chemistry》2020,58(22):3196-3208
Investigation of photopolymerization kinetics of 4-(4-methacryloyloxyphenyl)-butan-2-one (1) in comparison with 2-phenoxyethyl methacrylate (2) and phenyl methacrylate (3) using a UV-LED emitting at 395 nm shows significantly faster polymerization of 1 compared to both 2 and 3 at 40°C. Vitrification affects photopolymerization kinetics of all methacrylates under investigation. Interestingly, quantitative final conversion is observed during photoinitiated polymerization of 1 and 2 whereas 3 shows limited conversion at about 80%. Furthermore, higher degree of polymerization is obtained by photoinitiated polymerization of 1 compared to 2 and 3. This shows that the 3-oxobutyl substituent at the phenyl ring of 1 significantly affects both polymerization kinetics and final conversion of the photoinitiated polymerization. Moreover, an additional higher molecular weight fraction is observed in case of polymerization of 1 at 85°C that is above the glass transition temperature of the polymer formed during photoinitiated polymerization. As a thermal polymerization at 85°C in the absence of light results in a high molecular weight polymer as well, an additional thermal process may be discussed as reason for the higher molecular weight polymer fraction in case of the photopolymer made at 85°C. 相似文献
44.
Dr. Julie Martin Dr. Mohammad Wehbi Dr. Cécile Echalier Dr. Sylvie Hunger Dr. Audrey Bethry Prof. Xavier Garric Dr. Coline Pinese Prof. Jean Martinez Dr. Lubomir Vezenkov Prof. Gilles Subra Prof. Ahmad Mehdi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(56):12839-12845
A simple and efficient way to synthesize peptide-containing silicone materials is described. Silicone oils containing a chosen ratio of bioactive peptide sequences were prepared by acid-catalyzed copolymerization of dichlorodimethylsilane, hybrid dichloromethyl peptidosilane, and Si(vinyl)- or SiH-functionalized monomers. Functionalized silicone oils were first obtained and then, after hydrosilylation cross-linking, bioactive polydimethylsiloxane (PDMS)-based materials were straightforwardly obtained. The introduction of an antibacterial peptide yielded PDMS materials showing activity against Staphylococcus aureus. PDMS containing RGD ligands showed improved cell-adhesion properties. This generic method was fully compatible with the stability of peptides and thus opened the way to the synthesis of a wide range of biologically active silicones. 相似文献
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A series of novel diaroylhydrazone aluminum complexes have been synthesized and well-defined structurally, and their catalytic performance in the polymerization of ε-caprolactone and lactides have also been evaluated. Complexes [(L1–4)2AlMe] ( 1 – 4 ) {[L1 = (3,5-tBu2–2-OMe-C6H2)CH=NNCOC6H5], [L2 = (3,5-tBu2–2-OMe-C6H2)CH=NNCO(C6H4–4-OCH3)], [L3 = (3,5-tBu2–2-OMe-C6H2)CH=NNCO(C6H4–4-Br)] and [L4 = (2-OMe-C6H4)CH=NNCO(C6H4–4-tBu)]} were prepared through treatment of AlMe3 with the corresponding proligands L1–4H in molar ratios of 1: 1 or 1: 2. Chemical structures of all the complexes were well-defined by elemental analysis, NMR spectra as well as single-crystal X-ray study. Complexes [(L1–4)2AlMe] ( 1 – 4 ) in this work represent the first examples of aluminum complexes of aroylhydrazone ligands with crystallographic characterization. Specifically, they are all in monomeric form with a penta-coordinated aluminum center, including two approximately co-planar five-membered metallacycles with aluminum. Introduced bulky tert-butyl substituents in aroylhydrazone ligands could affect the geometry around the central metal which is a distorted square-based pyramid in complexes 1 – 3 while being a trigonal bipyramidal in complex 4 , thus affecting their catalytic behaviors. The complexes can successfully catalyze the ring-opening polymerization of ε-caprolactone and L-lactide under mild conditions without any activator. In addition, complexes 1 – 4 could also polymerize rac-lactide, affording atactic polylactides with high conversions and good controllability in relatively short reaction time. 相似文献
50.
Polycaprolactone (PCL) based α,ω-methacrylated macromonomer (DMPCL) was synthesized via enzymatic ring-opening polymerization (eROP) by using Novozyme 435 as the enzyme immobilized catalyst. DMPCL was further photopolymerized with monofunctional poly(ethylene glycol) methyl ether methacrylate (PEGMA-950) macromonomer and trimethylolpropane triacrylate (TMPTA) as tri-functionalized crosslinking agent in glass vials when CHCl3 was the solvent and Irgacure 819 was the photoinitiator. Ultraviolet (UV) Light Emitting Diode (LED) bulbs enabled photoinduced reactions at room temperature with low heat generation and high reaction efficiency. The obtained gels were characterized with Fourier Transform Infrared Spectroscopy (FT-IR) and Differential Scanning Calorimetry (DSC). DMPCL participated as an effective crosslinking agent in the photopolymerization of PEGMA-950. Combined usage of DMPCL and PEGMA-950 resulted in significantly more effective polymerization than the separate photopolymerizations of these macromonomers. 相似文献