scholarly journals Keggin-Type Heteropolyacid for Ring-Opening Polymerization of Cyclohexene Oxide: Molecular Weight Control

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Ahmed Aouissi ◽  
Zeid Abdullah Al-Othman ◽  
Abdurrahman Salhabi
Keyword(s):  
Molecular Weight ◽  
Reaction Time ◽  
Acetic Anhydride ◽  
Ring Opening ◽  
Weight Control ◽  
Reaction Medium ◽  
Resonance Spectroscopy ◽  
Cyclohexene Oxide ◽  
Scanning Calorimetry ◽  
Catalyst Amount

Polymerization of 1,2-cyclohexene oxide (CHO) in dichloromethane was catalyzed by 12-tungstophosphoric acid (H3PW12O40·13H2O) as a super solid acid. The effect of polymerization parameters such as reaction time, temperature, and catalyst amount was investigated. The effect of acetic anhydride as a ring-opening agent was also investigated. The resulting poly(1,2-cyclohexene oxide) (PCHO) was characterized by Fourier transform infrared (FTIR), nuclear magnetic resonance spectroscopy (1HNMR), gel-permeation chromatography (GPC), and differential scanning calorimetry (DSC). It has been found that the PCHO prepared over H3PW12O40·13H2O has a stereoregularity higher than that prepared over clay and Aluminium alkoxide catalysts. TheTgvalue obtained is due to the microstructure but not to molecular weight. The yield and the molecular weight of the polymer depend strongly on the reaction conditions. Molecular weights can be readily controlled by changing reaction temperature, reaction time, and catalyst amount. Contrary to most polymerization reactions, the molecular weight increases with the temperature increase. Addition of acetic anhydride to the reaction medium increased the yield threefold.

A high performance polybenzoxazine via smart ortho-norbornene functional benzoxazine monomer based on ring-opening metathesis polymerization

2018 ◽  
Vol 31 (5) ◽  
pp. 513-520 ◽  
Author(s):  
Kan Zhang ◽  
Yuqi Liu ◽  
Yuting Wang ◽  
Lin Sun
Keyword(s):  
Molecular Weight ◽  
Ring Opening ◽  
High Performance ◽  
Average Molecular Weight ◽  
Side Chain ◽  
Resonance Spectroscopy ◽  
Thermal Curing ◽  
Ring Opening Metathesis Polymerization ◽  
Scanning Calorimetry ◽  
Metathesis Polymerization

Monofunctional benzoxazine with ortho-norbornene functionality ( oHPNI-a) has been synthesized via Mannich condensation. The benzoxazine monomer containing norbornene group can be polymerized by ring-opening metathesis polymerization (ROMP) to form a side-chain benzoxazine functionalized polynorbornene (poly( oHPNI-a)side) with number-average molecular weight 3840 and weight-average molecular weight 7290. The structures of synthesized monomer and side-chain functionalized linear polymer have been confirmed by 1H nuclear magnetic resonance spectroscopy and Fourier transform infrared (FTIR) spectroscopy. The further thermal curing polymerization mechanisms of poly( oHPNI-a)side are monitored by in situ FTIR and differential scanning calorimetry (DSC). Activation energy of polymerization for poly( oHPNI-a)side is also studied by DSC. The polybenzoxazine obtained by ROMP and further thermally activated ring-opening polymerization exhibits much higher thermal stability than the polybenzoxazine directly formed by traditional thermal curing.

scholarly journals Effect of DMPA and Molecular Weight of Polyethylene Glycol on Water-Soluble Polyurethane

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 1915 ◽  
Author(s):  
Eyob Wondu ◽  
Hyun Woo Oh ◽  
Jooheon Kim
Keyword(s):  
Molecular Weight ◽  
Contact Angle ◽  
Polyethylene Glycol ◽  
Photoelectron Spectroscopy ◽  
Water Solubility ◽  
Soft Segment ◽  
Water Soluble ◽  
Size Exclusion ◽  
Resonance Spectroscopy ◽  
Scanning Calorimetry

In this study water-soluble polyurethane (WSPU) was synthesized from isophorone diisocyanate (IPDI), and polyethylene glycol (PEG), 2-bis(hydroxymethyl) propionic acid or dimethylolpropionic acid (DMPA), butane-1,4-diol (BD), and triethylamine (TEA) using an acetone process. The water solubility was investigated by solubilizing the polymer in water and measuring the contact angle and the results indicated that water solubility and contact angle tendency were increased as the molecular weight of the soft segment decreased, the amount of emulsifier was increased, and soft segment to hard segment ratio was lower. The contact angle of samples without emulsifier was greater than 87°, while that of with emulsifier was less than 67°, indicating a shift from highly hydrophobic to hydrophilic. The WSPU was also analyzed using Fourier transform infrared spectroscopy (FT-IR) to identify the absorption of functional groups and further checked by X-ray photoelectron spectroscopy (XPS). The molecular weight of WSPU was measured using size-exclusion chromatography (SEC). The structure of the WSPU was confirmed by nuclear magnetic resonance spectroscopy (NMR). The thermal properties of WSPU were analyzed using thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC).

Ring-Opening Polymerization of Lactide Using Aluminum Salen-Type Initiators

2014 ◽  
Vol 915-916 ◽  
pp. 713-716
Author(s):  
Qing Zhang ◽  
Jing Tian ◽  
Zhi Qi Cao ◽  
Ru Xia Xu ◽  
Zhen Zhen Sun ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Infrared Spectroscopy ◽  
Reaction Time ◽  
Magnetic Resonance ◽  
Schiff Bases ◽  
Reaction Temperature ◽  
Ring Opening ◽  
Ring Opening Polymerization ◽  
Resonance Spectroscopy ◽  
Aluminum Complex

In this investigation, Schiff bases aluminum complex was synthesized and used as the initiator in the polymerization of D,L-lactide. The aluminum complex was characterized by infrared spectroscopy (IR), and nuclear magnetic resonance spectroscopy (NMR). The influences of different factors, including reaction time, reaction temperature, and the ratio of D, L-lactide/Al3+ on the synthesis of polylactide were described. The results showed that Schiff bases aluminum complex could be successfully applied in the ring opening polymerization. The optimum condition of the ring opening polymerization of D,L-lactide, which included D,L-lactide/Al3+ (mol/mol) ratio of 250, reaction temperature of 120 °C, and reaction time of 16 hours.

scholarly journals Synthesis and Self-Assembly of Poly(N-Vinylcaprolactam)-b-Poly(ε-Caprolactone) Block Copolymers via the Combination of RAFT/MADIX and Ring-Opening Polymerizations

Polymers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1252
Author(s):  
Rodolfo M. Moraes ◽  
Layde T. Carvalho ◽  
Gizelda M. Alves ◽  
Simone F. Medeiros ◽  
Elodie Bourgeat-Lami ◽  
...  
Keyword(s):  
Block Copolymers ◽  
Ring Opening ◽  
Chain Transfer ◽  
Fluorescence Probe ◽  
Size Exclusion ◽  
Proton Nuclear Magnetic Resonance ◽  
Solution Temperature ◽  
Copolymer Composition ◽  
Resonance Spectroscopy ◽  
Scanning Calorimetry

Well-defined amphiphilic, biocompatible and partially biodegradable, thermo-responsive poly(N-vinylcaprolactam)-b-poly(ε-caprolactone) (PNVCL-b-PCL) block copolymers were synthesized by combining reversible addition-fragmentation chain transfer (RAFT) and ring-opening polymerizations (ROP). Poly(N-vinylcaprolactam) containing xanthate and hydroxyl end groups (X–PNVCL–OH) was first synthesized by RAFT/macromolecular design by the interchange of xanthates (RAFT/MADIX) polymerization of NVCL mediated by a chain transfer agent containing a hydroxyl function. The xanthate-end group was then removed from PNVCL by a radical-induced process. Finally, the hydroxyl end-capped PNVCL homopolymer was used as a macroinitiator in the ROP of ε-caprolactone (ε-CL) to obtain PNVCL-b-PCL block copolymers. These (co)polymers were characterized by Size Exclusion Chromatography (SEC), Fourier-Transform Infrared spectroscopy (FTIR), Proton Nuclear Magnetic Resonance spectroscopy (1H NMR), UV–vis and Differential Scanning Calorimetry (DSC) measurements. The critical micelle concentration (CMC) of the block copolymers in aqueous solution measured by the fluorescence probe technique decreased with increasing the length of the hydrophobic block. However, dynamic light scattering (DLS) demonstrated that the size of the micelles increased with increasing the proportion of hydrophobic segments. The morphology observed by cryo-TEM demonstrated that the micelles have a pointed-oval-shape. UV–vis and DLS analyses showed that these block copolymers have a temperature-responsive behavior with a lower critical solution temperature (LCST) that could be tuned by varying the block copolymer composition.

scholarly journals Poly(lactic acid) polymer stars built from early generation dendritic polyols

2013 ◽  
Vol 91 (6) ◽  
pp. 392-397 ◽  
Author(s):  
Genny E. Keefe ◽  
Jean-d'Amour K. Twibanire ◽  
T. Bruce Grindley ◽  
Michael P. Shaver
Keyword(s):  
Molecular Weight ◽  
Ring Opening ◽  
Gel Permeation Chromatography ◽  
Poly Lactic Acid ◽  
Reactive Site ◽  
Scanning Calorimetry ◽  
Early Generation ◽  
Sequential Reaction ◽  
Cyclic Esters ◽  
Total Molecular Weight

A family of polymer stars has been prepared from early generation dendritic cores with four, six, and eight arms. Four dendritic cores were prepared from the sequential reaction of a multifunctional alcohol with a protected anhydride, followed by deprotection to afford two or three new alcohol functionalities per reactive site. These cores were used as initiators for the tin-catalyzed ring-opening polymerization of l-lactide and rac-lactide to afford isotactic and atactic degradable stars, respectively. Two series of stars were prepared for each monomer, either maintaining total molecular weight or number of monomer units per arm. The polymers were characterized by NMR spectroscopy, light-scattering gel-permeation chromatography, differential scanning calorimetry, and thermogravimetric analysis. Our results support previous work that suggests that the length of the arms dictates thermal properties rather than the total molecular weight of the star. Little effect was noted between aromatic and aliphatic cores, presumably due to the flexibility of the rest of the core molecule. We have shown that early generation dendrimers can serve as excellent core structures for building core-first polymer stars via the ring-opening of cyclic esters.

Simultaneous Control of 1,4-cis Selectivity and Molecular Weight of Polymer in Polymerization of Butadiene with Co(acac)3/MAO Catalyst

2005 ◽  
Vol 78 (1) ◽  
pp. 143-154 ◽  
Author(s):  
Kiyoshi Endo ◽  
Naoyoshi Hatakeyama
Keyword(s):  
Molecular Weight ◽  
Reaction Time ◽  
Active Site ◽  
Weight Control ◽  
Catalyst Preparation ◽  
Polymerization Rate ◽  
Polymerization Time ◽  
Molecular Weights ◽  
Molecular Weight Control ◽  
Simultaneous Control

Abstract Simultaneous control of 1,4-cis selective polymerization and molecular weight of polymer in the polymerization of butadiene (BD) with Co(acac)3/MAO catalyst was investigated. The polymerization of BD with the Co(acac)3/MAO catalyst strongly depended on catalyst preparation, and the polymerization rate of BD with Co(acac)3 activated by MAO in the presence of BD was faster than that with previous reported results that the Co(acac)3 activated by MAO in the absence of BD. From a kinetic study, linear relation between ln[BD]0/[BD]t and polymerization time and no induction period for the polymerization were observed in the polymerization of BD with Co(acac)3 activated by MAO in the presence of BD. This indicates that the active site for the polymerization kept constant throughout polymerization. The molecular weights of the polymers increased linearly with polymer yields, and the line passed through the original point. The Mw/Mn of the polymers kept constant during reaction time. The polymerization of BD performed at 0 °C in the Co(acac)3/MAO catalyst gave high molecular weight 1,4-cis poly(BD) (1,4-cis content > 95) and narrow polydispersity (Mw/Mn=1.36). On the basis of these results, it is clear that simultaneous 1,4-cis selective and molecular weight control is possible in the polymerization of BD with the Co(acac)3/MAO catalyst.

FUNCTIONALIZATION OF ACRYLONITRILE BUTADIENE RUBBER WITH META-PENTADECENYL PHENOL, A MULTIFUNCTIONAL ADDITIVE AND A RENEWABLE RESOURCE

2017 ◽  
Vol 90 (4) ◽  
pp. 683-698 ◽  
Author(s):  
Satyajit Samantarai ◽  
Denial Mahata ◽  
Ahindra Nag ◽  
Golok B. Nando ◽  
Narayan C. Das
Keyword(s):  
Molecular Weight ◽  
Flow Behavior ◽  
Renewable Resource ◽  
Resonance Spectroscopy ◽  
Butadiene Rubber ◽  
Scanning Calorimetry ◽  
Flow Behavior Index ◽  
Multifunctional Additive ◽  
Acrylonitrile Butadiene Rubber ◽  
Index Value

ABSTRACT The present invention deals with the functionalization of acrylonitrile butadiene rubber (NBR) by chemically grafting meta-pentadecenyl phenol (cardanol) onto the backbone chain. This imparts inherent multifunctional characteristics to the nitrile rubber. The grafting of cardanol onto NBR was accomplished successfully in emulsion stage using benzoyl peroxide (BPO) as a free radical initiator. The grafted NBR is characterized by ultraviolet–visible, Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, and gel permeation chromatography. Cardanol grafted NBR (CGNBR) shows an increase in molecular weight (6.6%) with an increase in polydispersity index value. The optimal conditions of grafting are found out to be, “1 phr BPO, 15 phr cardanol, at a reaction temperature of 60 °C and a reaction time 10 h” by using the “Taguchi L9 orthogonal array” method. The grafting efficiency and percentage grafting are calculated to be 79.2% and 7.1%, respectively, at the optimum combination of parameters. The CGNBR shows an increase in molecular weight and reduction in Wallace plasticity number as well as Mooney viscosity, but exhibits a higher plasticity retention index value, as compared to ungrafted NBR. The rheological characteristics of CGNBR exhibit a better flow behavior index than NBR. Differential scanning calorimetry, dynamic mechanical analysis results exhibit a decrease in Tg value for grafted NBR. Thermogravimetric analysis results displayed an increase in thermal stability of the functionalized NBR than that of raw NBR.

scholarly journals Poly(glycolide) multi-arm star polymers: Improved solubility via limited arm length

2010 ◽  
Vol 6 ◽  
Author(s):  
Florian K Wolf ◽  
Anna M Fischer ◽  
Holger Frey
Keyword(s):  
Molecular Weight ◽  
Ring Opening ◽  
Biomedical Applications ◽  
Weight Control ◽  
Glycolic Acid ◽  
Polymer Melt ◽  
Degree Of Polymerization ◽  
Star Block Copolymers ◽  
Grafting From ◽  
Low Solubility

Due to the low solubility of poly(glycolic acid) (PGA), its use is generally limited to the synthesis of random copolyesters with other hydroxy acids, such as lactic acid, or to applications that permit direct processing from the polymer melt. Insolubility is generally observed for PGA when the degree of polymerization exceeds 20. Here we present a strategy that allows the preparation of PGA-based multi-arm structures which significantly exceed the molecular weight of processable oligomeric linear PGA (<1000 g/mol). This was achieved by the use of a multifunctional hyperbranched polyglycerol (PG) macroinitiator and the tin(II)-2-ethylhexanoate catalyzed ring-opening polymerization of glycolide in the melt. With this strategy it is possible to combine high molecular weight with good molecular weight control (up to 16,000 g/mol, PDI = 1.4–1.7), resulting in PGA multi-arm star block copolymers containing more than 90 wt % GA. The successful linkage of PGA arms and PG core via this core first/grafting from strategy was confirmed by detailed NMR and SEC characterization. Various PG/glycolide ratios were employed to vary the length of the PGA arms. Besides fluorinated solvents, the materials were soluble in DMF and DMSO up to an average arm length of 12 glycolic acid units. Reduction in the T g and the melting temperature compared to the homopolymer PGA should lead to simplified processing conditions. The findings contribute to broadening the range of biomedical applications of PGA.

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