Mn Of Poly Research Articles

Preparation and activity of ruthenium catalyst based on β-cyclodextrin for ring-opening metathesis polymerization

Inspired by substrates-recognition of enzymes, we prepared supramolecular catalyst (Ru-βCD Cat) for ring-opening metathesis polymerization (ROMP) by modifying second generation Grubbs catalyst® (M204) with β-cyclodextrin (βCD) derivative (VPhe-βCD). The ROMP activity of Ru-βCD Cat was demonstrated using 7-oxanorbornene-2,3-dicarboxylic acid dimethyl ester (ONorCOOMe). The VPhe-βCD cavity recognized the ONorCOOMe monomer and attached to catalytic metal center of Ru-βCD Cat to grow poly(ONorCOOMe) with higher yield and molecular weight (Mn) in aqueous medium. The yield and Mn were higher than those of poly(ONorCOOMe) obtained by second generation Hoveyda-Grubbs catalyst® (M720). 1-Adamantanol hindered ONorCOOMe from occupying the βCD cavity, acting as a competitive guest molecule. The inhibition caused lower polymer yield and Mn. These results showed that molecular recognition of ONorCOOMe by the cavity of Ru-βCD Cat is important to increase the polymer yield and Mn of poly(ONorCOOMe).

Vanillin derived a carbonate dialdehyde and a carbonate diol: novel platform monomers for sustainable polymers synthesis.

Vanillin has been regarded as one of the important biomass-based platform chemicals for aromatic polymers synthesis. Herein, novel symmetric bis(4-formyl-2-methoxyphenyl)carbonate (BFMC) and bis(4-(hydroxymethyl)-2-methoxyphenyl)carbonate (BHMC) polymeric monomers have been synthesized in high yields using vanillin as a raw chemical, which have been submitted for polymer synthesis via well-established polymeric strategies. A new class of poly(carbonate ester)s oligomers with amide moieties in their side chain can be prepared by using the BFMC as one of monomers via the Passerini three compound reaction (3CR). A new class of poly(carbonate ester)s oligomers and poly(carbonate urethane)s can be prepared via reactions between BHMC with dicarboxylic acid chlorides and diisocyanates, respectively. Their structure have been confirmed by 1H NMR, 13C NMR and FTIR, and the gel permeation chromatograph (GPC) analysis shows that the Mn of poly(carbonate ester)s oligomers ranges from 3100 to 7900 with PDI between 1.31 and 1.65, and the Mn of poly(carbonate urethane)s ranges from 16 400 to 24 400 with PDI ranging from 1.36 to 2.17. The DSC analysis shows that the poly(carbonate ester)s oligomers have relative low Tg ranging from 37.4 to 74.1 °C, and the poly(carbonate urethane)s have Tg ranging from 97.3 to 138.3 °C, mainly correlating to the structure of dicarboxylic acid chlorides and diisocyanates used.

Well-Defined Poly(sulfobetaine) Brushes Prepared by Surface-Initiated ATRP Using a Fluoroalcohol and Ionic Liquids as the Solvents

Surface-initiated atom transfer radical polymerization (ATRP) of 2-(N-2-methacryloyloxyethyl-N,N-dimethyl) ammonatoethanesulfonate) (MAES), 3-(N-2-methacryloyloxyethyl-N,N-dimethyl) ammonatopropanesulfonate) (MAPS), and 4-(N-2-methacryloyloxyethyl-N,N-dimethyl) ammonatobutanesulfonate) (MABS) was carried out in 2,2,2-trifluoroethanol (TFE) containing a small amount of 1-hexyl-3-methylimidazolium chloride at 60 °C to produce well-defined poly(sulfobetaine) brushes and the corresponding free polymers with predictable number-average molecular weight (Mn, 1 × 104 to 3 × 105 g mol−1) and narrow molecular weight distributions (Mw/Mn < 1.2). A first-order kinetic plot for ATRP of MAPS revealed a linear relationship between the monomer conversion index (ln([M]0/[M])) and polymerization time. The polymerization rates decreased with increasing ionic liquid concentration. The Mn of poly(MAPS) increased in proportion to the conversion. The sequential polymerization of MAPS initiated with the chain ends of poly(MAPS) ...

Direct Synthesis of Well-Defined Poly[{2-(methacryloyloxy)ethyl}trimethylammonium chloride] Brush via Surface-Initiated Atom Transfer Radical Polymerization in Fluoroalcohol

A well-defined cationic polymer and polymer brush were simultaneously prepared by copper-catalyzed atom transfer radical polymerization (ATRP) of 2-(methacryloxy)ethyltrimethylammonium chloride (MTAC) in 2,2,2-trifluoroethanol (TFE) at 60 °C initiated with ethyl 2-bromoisobutylate and the corresponding alkylbromide immobilized on silicon wafer. ATRP of MTAC in TFE as well as aqueous solution proceeded quickly but in a poorly controlled manner, leading to a relatively higher molecular weight distribution (MWD) than Mw/Mn = 1.3, where Mw and Mn are weight-average and number-average molecular weights, respectively. Addition of a small amount of isopropyl alcohol to the TFE-based reaction mixture reduced the polymerization rate and produced a poly(MTAC) with predictable molecular weight and narrower MWD than 1.19. The Mn of poly(MTAC) was controllable in the range 104−105 g mol−1 based on the molar ratio of monomer and initiator in the feed. The Mn of the brush on a flat silicon wafer matched that of the free poly(MTAC). The graft density of poly(MTAC) was 0.20 chains nm−2. The ATRP of MTAC in TFE/1-ethyl-3-methylimidazolium chloride (EMImCl) also proceeded in a controlled manner at 60 °C, yielding polymers with narrow MWDs (Mw/Mn = 1.12−1.13). Analysis of the 13C NMR spectra of the carbonyl region of the resulting poly(MTAC)s revealed that syndiotactic-rich configurations were produced by ATRP of MTAC in aqueous solution, TFE/isopropyl alcohol, and TFE/EMImCl. The solvent effect of TFE and ionic liquid on the tacticity of polymer was negligible.

Dependence of biodegradation and release behavior on physical properties of poly(caprolactone)‐based polyurethanes

AbstractSimultaneous pursuit of long accurate release control and high biodegradation rate is required as the membrane of controlled‐release devices in agriculture. The effect of the physical properties of poly(caprolactone) based polyurethanes as a polymer membrane on their biodegradation characteristics and the release profile was evaluated. The soil burial test at 28°C resulted that the biodegradation rate of the polyurethanes increased as the number of average molecular weight (Mn) of poly(caprolactone) diol used increased from 500 to 1000, whereas it decreased as the Mn of poly(caprolactone) diol increased from 1200 to 2000. The biodegradation behavior was different when the Mn of poly(caprolactone) diols was used because of the recrystallization of long straight poly(caprolactone) chains. Poly(caprolactone) triol prevented recrystallization and led the high degradation ratio. The release rate of urea from the polyurethane‐coated granules decreased as the Mn of poly(caprolactone) polyol decreased. These results indicated that the release profile was affected by the urethane content, and the biodegradation characteristic was affected by the glass transition temperature and the recrystallization of polyurethane membrane. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Synthesis of hetero‐telechelic polymers by self‐polyaddition of monomers containing both oxetanyl and carboxyl groups

AbstractThe synthesis and self‐polyaddition of new monomers, o‐, m‐, and p‐[(3‐ethyloxetane‐3‐yl)methoxyethyl]benzoic acid (o‐EOMB, m‐EOMB, and p‐EOMB) containing both oxetanyl groups and carboxyl groups were examined. The reactions of o‐EOMB, m‐EOMB, and p‐EOMB in the presence of tetraphenylphosphonium bromide as a catalyst in o‐dichlorobenzene at 150–170 °C resulted in self‐polyaddition to give the corresponding hetero‐telechelic polymers poly(o‐EOMB), poly(m‐EOMB), and poly(p‐EOMB) with Mns = 14,500–33,400 in satisfactory yields. The Mn of poly(o‐EOMB) decreased at higher reaction temperatures than 150 °C, unlike those of poly(m‐EOMB) and poly(p‐EOMB), possibly due to inter‐ or intraester exchange side reactions. It was also found that the thermal properties and solubilities of these polymers were supposed with the proposed structures. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7835–7842, 2008

Relationship between superficial response to environmental changes and adhesive property of polyurethane cross‐linked polyacrylate network

AbstractA polyacrylic network containing carboxyl groups was cross‐linked with polyurethane. The dynamic contact angles (DCA) on specimens were estimated in water. The effect of ingredient ratio and average molecular M̄n of poly(oxypropylene glycol) (PPG) on DCA were investigated. Data obtained are correlated with 180° peel strength by using the polymer network as an adhesive to adhere both poly(vinyl chloride) (PVC) and polyethylene (PE) film. Results reveal that there is correlation of the surface response to bilateral adhesion of polar and nonpolar substrates. © 1994 John Wiley &amp; Sons, Inc.

Chain transfer reaction in the polymerization of substituted acetylenes. II. Chain transfer reaction to trimethylvinylsilane in the polymerization of disubstituted acetylenes by MoCl5–n‐Bu4Sn

AbstractThe effect of various olefins as chain transfer agents was studied in the polymerization of 1‐chloro‐1‐octyne, 1‐chloro‐2‐phenylacetylene, 2‐octyne, etc., catalyzed by MoCl5–n‐Bu4Sn (1 : 1). Si‐containing olefins, especially trimethylvinylsilane, greatly lowered the polymer molecular weight in the polymerization of the Cl‐containing acetylenes, e.g., the Mn of poly(1‐chloro‐1‐octyne) was 4.2 × 105 without an olefin, whereas it decreased to 3.4 × 104, i.e., below 1/10 in the presence of trimethylvinylsilane (1/2 equiv to monomer). In contrast, the molecular weight of poly(2‐octyne) did not decrease that much, even with trimethylvinylsilane. The Cl‐containing polyacetylenes obtained in the presence of trimethylvinylsilane as chain transfer agent possessed the trimethylsilyl group. Thus, the present study enables control of the molecular weight of substituted polyacetylenes by chain transfer, and further verifies the metal carbene mechanism for the polymerization of substituted acetylenes. © 1993 John Wiley &amp; Sons, Inc.