Silica supported Schiff-base cobaltIII complex-Lewis base system: a highly selective catalyst for alternating copolymerization of CO2 and propylene oxide

e-Polymers ◽  
2011 ◽  
Vol 11 (1) ◽  
Author(s):  
Yongsheng Niu ◽  
Hongchun Li
Keyword(s):  
Molecular Weight ◽  
Schiff Base ◽  
Reaction Time ◽  
Propylene Oxide ◽  
Cobalt Complex ◽  
Catalyst System ◽  
Cyclic Carbonate ◽  
Lewis Base ◽  
Molar Ratio ◽  
Base System

AbstractAn binary catalyst system of a silica supported Schiff-base cobalt complex SalenCoIII (OAC)-MCM-41 (Salen = 3-[N,N-bis-2-(3,5-di-tert-butylsalicylidenamino) ethyl] amine) was developed to generate the copolymerization of CO2 and propylene oxide in presence of (4-dimethylamino)-pyridine (DMAP). The influence of the molar ratio of catalyst components, the operating temperature, reaction time, and CO2 pressure on the yield as well as the molecular weight of polycarbonate was systematically investigated. The high selectivity of polycarbonate over cyclic carbonate at 40 °C was maintained after a longer reaction time to attain quantitative formation of the alternating copolymer. High molecular weight of 67 000 were achieved at an appropriate combination of all variables.

scholarly journals A New Dinuclear Cobalt Complex for Copolymerization of CO2 and Propylene Oxide: High Activity and Selectivity

Molecules ◽  
2020 ◽  
Vol 25 (18) ◽  
pp. 4095
Author(s):  
Wen-Zhen Wang ◽  
Kai-Yue Zhang ◽  
Xin-Gang Jia ◽  
Li Wang ◽  
Lei-Lei Li ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Propylene Carbonate ◽  
Propylene Oxide ◽  
Catalytic Reaction ◽  
Density Functional ◽  
Cobalt Complex ◽  
Catalyst System ◽  
High Catalytic Activity ◽  
Weight Yield ◽  
Carbon Dioxide Co2

Based on the ligand H4Salen-8tBu (salen-4), a new dinuclear cobalt complex (salen-4)[Co(III)TFA]2 (salen-4 = 3,5-di-tert-butylsalicylaldehyde-3,3′-diaminobiphenylamine; TFA = trifluoroacetic acid) has been firstly synthesized and characterized. It shows high catalytic activity for the copolymerization of propylene oxide (PO) and carbon dioxide (CO2), yielding regioregular poly(propylene carbonate) (PPC) with little generation of propylene carbonate (PC) by-product. It has been found that (salen-4)[Co(III)TFA]2 shows higher activity at milder conditions, generating a polymer with maximum Mn of 293 kg/mol and a narrow molecular weight distribution PDI of 1.35. The influences of reaction time, CO2 pressure, reaction temperature, nature of the cocatalyst, catalyst dosage and substrate concentration on the molecular weight, yield and selectivity of the polymer were explored in detail. The results showed that the (salen-4)[Co(III)TFA]2/[PPN]TFA catalyst system demonstrated a remarkable TOF as high as 735 h–1. In addition, a hypothetical catalytic reaction mechanism was proposed based on density functional theory (DFT) calculations and the catalytic reaction results of the (salen-4)[Co(III)TFA]2.

Synthesis of Double Alkyl EO/PO Random Copolyethers with KOH Catalyst

2012 ◽  
Vol 472-475 ◽  
pp. 2681-2685
Author(s):  
Jian Guo Guo ◽  
Su Qin He ◽  
Jian Ming Jiang
Keyword(s):  
Molecular Weight ◽  
Ethylene Oxide ◽  
Propylene Oxide ◽  
Potassium Hydroxide ◽  
Random Copolymer ◽  
Alkyl Halides ◽  
Ethyl Bromide ◽  
Hydroxyl Group ◽  
Molar Ratio ◽  
End Capping

Ethylene oxide (EO) and propylene oxide (PO) random copolymer was synthesized with 1,2-propanediol as initiator, then the end-capping process was carried out by adding various alkyl halides and potassium hydroxide (KOH) to produce the double alkyl EO/PO random copolyethers. The factors effecting alkyl-capping rate were discussed. The results showed that when the molar ratio of hydroxyl group/KOH/1-bromobutane was 1/1.9/1.9, reacting time 6.5 hr and reacting temperature 50°C, the alkyl-capping rate could reach over 80%. The end-capping rate would also increase with the increasing content of ethylene oxide in the random polyether, and the end-capping rate of the EO/PO/EO block-polyether was high than that of the random polyether with same molecular weight. Instead of 1-bromobutane, ethyl bromide promised a higher whereas chloralkane gave a lower end-capping rate respectively.

scholarly journals An Investigation of the Organoborane/Lewis Base Pairs on the Copolymerization of Propylene Oxide with Succinic Anhydride

Molecules ◽  
2020 ◽  
Vol 25 (2) ◽  
pp. 253 ◽  
Author(s):  
Lan-Fang Hu ◽  
Dan-Jing Chen ◽  
Jia-Liang Yang ◽  
Xing-Hong Zhang
Keyword(s):  
Propylene Oxide ◽  
Succinic Anhydride ◽  
Lewis Base ◽  
Molar Ratio ◽  
Base Pairs ◽  
Catalytic Systems ◽  
Aliphatic Polyesters ◽  
Lewis Bases ◽  
Molecular Weights ◽  
High Ester

The copolymerization of biorenewable succinic anhydride (SA) with propylene oxide (PO) is a promising way to synthesize biodegradable aliphatic polyesters. However, the catalytic systems for this reaction still deserve to be explored because the catalytic activity of the reported catalysts and the molecular weights of produced polyesters are unsatisfied. Herein, we investigate the copolymerization of SA with PO catalyzed by the organoborane/base pairs. The types of Lewis bases, organoboranes, and their loadings all have a large impact on the activity and selectivity of the copolymerization. High ester content of >99% was achieved when performed the PO/SA copolymerization using triethyl borane (TEB)/phosphazene base P1-t-Bu (t-BuP1) pair with a molar ratio of 1/1 at 30–80 °C. Using TEB/t-BuP1 pair with the molar ratio of 4/1 at 80 °C, the turnover of frequency (TOF) was up to 128 h−1 and clearly higher than the known TOF values (0.5–34 h−1) of the PO/SA copolymerization by previously reported catalysts. The number-average molecular weights (Mns) of the resultant polyesters reached up to 20.4 kg/mol when copolymerization was carried out using TEB/t-BuP1 (1/1, in molar ratio) at 30 °C.

Binary molybdenum-based catalyst for coordination polymerization of styrene

2016 ◽  
Vol 49 (5) ◽  
pp. 408-421 ◽  
Author(s):  
Jieting Geng ◽  
Youguo Shao ◽  
Feng Song ◽  
Feng Li ◽  
Jing Hua
Keyword(s):  
Molecular Weight ◽  
Catalyst Activity ◽  
Average Molecular Weight ◽  
Gel Permeation Chromatography ◽  
Catalyst System ◽  
Bulk Polymerization ◽  
Molar Ratio ◽  
Scanning Calorimetry ◽  
Coordination Polymerization ◽  
Co Catalyst

Coordination polymerization of styrene (St) using molybdenum pentachloride supported by phosphite ligand in the presence of metal organic compound was studied for the first time. The types of phosphite and co-catalysts significantly affected the catalytic activity of the molybdenum (V) (Mo(V)) active center and the number-average molecular weight ( Mn) of the resultant polymer. Among the examined catalysts, tri(nonylphenyl)phosphite (TNPP) ligand and AlOPhCH3( i-Bu)2 as co-catalyst provided the polymer with highest yield (up to 87.1%), metallocene as co-catalyst provided the polymer with highest Mn (up to 5.32 × 105). The effect of [P]/[Mo] molar ratio on catalyst activity of the polymerization was discussed and the structures of Mo·TNPP complexes were preliminarily studied by infrared (IR) and ultraviolet spectroscopies. Besides, the polystyrene (PS) samples synthesized through bulk polymerization and solution polymerization were characterized by gel permeation chromatography, IR, carbon 13 nuclear magnetic resonance, and differential scanning calorimetry, respectively, and the results indicated both of the PS had high molecular weight (approximately 105) and atactic structure. All these results demonstrated that Mo(V) catalyst system was very effective for St polymerization.

scholarly journals A New Synthesis Strategy on Styrene-Butadiene Di-Block Copolymer Containing High cis-1,4 Unit Via Transfer of Anionic to Coordination Polymerization

Polymers ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 195 ◽  
Author(s):  
Jie Liu ◽  
Xin Min ◽  
Xiuzhong Zhu ◽  
Zichao Wang ◽  
Tong Wang ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Block Copolymer ◽  
Catalyst System ◽  
Boron Trifluoride Etherate ◽  
Molar Ratio ◽  
Feed Ratio ◽  
Complex Catalyst ◽  
Coordination Polymerization ◽  
Synthesis Strategy ◽  
Styrene Butadiene

A novel synthesis strategy on styrene-butadiene di-block copolymer (PS-b-PB) with high cis-1,4 unit content was developed, based on a transfer technique from anionic to coordination polymerization. Firstly, the styrene monomer was initiated by n-butyllithium (Li) utilizing anionic polymerization at 50 °C, which resulted in a macromolecular alkylating initiator (PSLi). Secondly, PSLi was aged with nickel naphthenate (Ni) and boron trifluoride etherate (B) for obtaining a complex catalyst system (Ni/PSLi/B). Then, Ni/PSLi/B was applied to initiate the butadiene (Bd) polymerization. Following this new strategy, a series of PS-b-PBs were successfully synthesized. The experimental results indicated that under the molar ratio combination of [Li]/[Ni] = 5 and [B]/[Li] = 1, styrene-butadiene di-block copolymers could be easily achieved with high cis-1,4 unit content (>97%) and controlled molecular weight as well as narrow molecular weight distribution (Mw/Mn < 1.5). Furthermore, the copolymer’s block ratio could also be effectively controlled by controlling the two components’ monomer feed ratio.

scholarly journals In-Situ Rheological Studies of Cationic Lignin Polymerization in an Acidic Aqueous System

Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 2982
Author(s):  
Samira Gharehkhani ◽  
Weijue Gao ◽  
Pedram Fatehi
Keyword(s):  
Molecular Weight ◽  
Reaction Time ◽  
Reaction System ◽  
Reaction Medium ◽  
Molar Ratio ◽  
Process Conditions ◽  
Trimethylammonium Chloride ◽  
Tan Δ ◽  
Lignin Polymerization

The chemistry of lignin polymerization was studied in the past. Insights into the rheological behavior of the lignin polymerization system would provide crucial information required for tailoring lignin polymers with desired properties. The in-situ rheological attributes of lignin polymerization with a cationic monomer, [2-(methacryloyloxy)ethyl] trimethylammonium chloride (METAC), were studied in detail in this work. The influences of process conditions, e.g., temperature, component concentrations, and shear rates, on the viscosity variations of the reaction systems during the polymerization were studied in detail. Temperature, METAC/lignin molar ratio, and shear rate increases led to the enhanced viscosity of the reaction medium and lignin polymer with a higher degree of polymerization. The extended reaction time enhanced the viscosity attributing to the larger molecular weight of the lignin polymer. Additionally, the size of particles in the reaction system dropped as reaction time was extended. The lignin polymer with a larger molecular weight and Rg behaved mainly as a viscose (tan δ > 1 or G″ > G′) material, while the lignin polymer generated with smaller molecular weight and shorter Rg demonstrated strong elastic characteristics with a tan (δ) lower than unity over the frequency range of 0.1−10 rad/s.

Study on Synthesis of Epoxy Resin Modified with Polysiloxane

2014 ◽  
Vol 496-500 ◽  
pp. 193-197
Author(s):  
Jiang Ling Han ◽  
Hui Lu Li ◽  
Kang Chen Shao ◽  
Wen Liu
Keyword(s):  
Molecular Weight ◽  
Reaction Time ◽  
Epoxy Resin ◽  
Reaction Temperature ◽  
Silicone Oil ◽  
Glycidyl Ether ◽  
Molar Ratio ◽  
Allyl Glycidyl Ether ◽  
Modified Epoxy ◽  
Epoxy Value

With allyl glycidyl ether and terminal hydrogen silicone oil, in certain conditions, the silicone-modified epoxy resin synthesized by the hydrosilylation reaction. This study discuss the effect of the structure and properties on the synthesized product, such as the catalyst, reaction time, reaction temperature and the C = C/Si-H molar ratio of allyl glycidyl ether and terminal hydrogen silicone oil. Infrared spectroscopy, gel permeation chromatography (GPC), epoxy value and hydrolysis chlorine of the polysiloxane-modified epoxy resin were characterized and analysized. The results show that the terminal hydrogen silicone oil-modified epoxy resin has balanced epoxy value, molecular weight and molecular weight distribution, the conversion of reactive hydrogen is the highest when the dosage of H2PtCl66H2O is 0.01% to 0.02% of reactant in weight, the molar ratio of C=C /Si-H in AGE (allyl glycidyl ether) and the terminal of hydrogen silicone oil is 4.28:1, the reaction temperature is 80°C to 85°C, reaction time is controlled in 6 hours.

Metathesis Polymerization of Phenylacetylene by Tungsten Aryloxo Complexes

1995 ◽  
Vol 60 (3) ◽  
pp. 489-497 ◽  
Author(s):  
Hynek Balcar ◽  
Jan Sedláček ◽  
Marta Pacovská ◽  
Vratislav Blechta
Keyword(s):  
Molecular Weight ◽  
Catalytic Activity ◽  
Induction Period ◽  
Average Molecular Weight ◽  
Molar Fraction ◽  
Molar Ratio ◽  
Weight Average Molecular Weight ◽  
Polymer Yield ◽  
Positive Effect ◽  
Ligand Addition

Catalytic activity of the tungsten aryloxo complexes WCl5(OAr) and WOCl3(OAr), where Ar = 4-t-C4H9C6H4, 2,6-(t-C4H9)2C6H3, 2,6-Cl2C6H3, 2,4,6-Cl3C6H2, and 2,4,6-Br3C6H2 in polymerization of phenylacetylene (20 °C, monomer to catalyst molar ratio = 1 000) was studied. The activity of WCl5(OAr) as unicomponent catalysts increases with increasing electron withdrawing character of the -OAr ligand. Addition of two equivalents of organotin cocatalysts (Me4Sn, Bu4Sn, Ph4Sn, Bu3SnH) to WCl5(O-C6H2Cl3-2,4 ,6) has only slight positive effect (slightly higher polymer yield and/or molecular weight of poly(phenylacetylene)s was achieved). However, in the case of WOCl3(O-C6H3Cl2-2, 6) catalyst, it enhances the activity considerably by eliminating the induction period. Poly(phenylacetylene)s prepared with the catalysts studied have weight-average molecular weight ranging from 100 000 to 200 000. They are trans-prevailing and have relatively low molar fraction of monomer units comprised in cyclohexadiene sequences (about 6%).

scholarly journals Highly Efficient MOF Catalyst Systems for CO2 Conversion to Bis-Cyclic Carbonates as Building Blocks for NIPHUs (Non-Isocyanate Polyhydroxyurethanes) Synthesis

Catalysts ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 628
Author(s):  
Adolfo Benedito ◽  
Eider Acarreta ◽  
Enrique Giménez
Keyword(s):  
Molar Mass ◽  
Cycloaddition Reaction ◽  
Building Blocks ◽  
Catalyst System ◽  
Cyclic Carbonate ◽  
Ammonium Bromide ◽  
Cyclic Carbonates ◽  
High Molar Mass ◽  
Highly Efficient ◽  
Free Process

The present paper describes a greener sustainable route toward the synthesis of NIPHUs. We report a highly efficient solvent-free process to produce [4,4′-bi(1,3-dioxolane)]-2,2′-dione (BDC), involving CO2, as renewable feedstock, and bis-epoxide (1,3-butadiendiepoxide) using only metal–organic frameworks (MOFs) as catalysts and cetyltrimethyl-ammonium bromide (CTAB) as a co-catalyst. This synthetic procedure is evaluated in the context of reducing global emissions of waste CO2 and converting CO2 into useful chemical feedstocks. The reaction was carried out in a pressurized reactor at pressures of 30 bars and controlled temperatures of around 120–130 °C. This study examines how reaction parameters such as catalyst used, temperature, or reaction time can influence the molar mass, yield, or reactivity of BDC. High BDC reactivity is essential for producing high molar mass linear non-isocyanate polyhydroxyurethane (NIPHU) via melt-phase polyaddition with aliphatic diamines. The optimized Al-OH-fumarate catalyst system described in this paper exhibited a 78% GC-MS conversion for the desired cyclic carbonates, in the absence of a solvent and a 50 wt % chemically fixed CO2. The cycloaddition reaction could also be carried out in the absence of CTAB, although lower cyclic carbonate yields were observed.

Sign in / Sign up

Export Citation Format

Share Document