scholarly journals A Complexed Initiating System AlCl3·Phenetole/TiCl4·H2O with Dominant Synergistic Effect for Efficient Synthesis of High Molecular Weight Polyisobutylene

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2121
Author(s):  
Yulong Jin ◽  
Liang Chen ◽  
Xing Guo ◽  
Linfeng Xu ◽  
Zhihua Zhu ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Synergistic Effect ◽  
High Molecular Weight ◽  
Monomer Concentration ◽  
Catalyst System ◽  
Polymerization Temperature ◽  
Simple Preparation ◽  
Order Of Magnitude ◽  
Unique Approach ◽  
High Molecular Weight Polyisobutylene

A complexed initiating system AlCl3·phenetole/TiCl4·H2O was prepared by simply compounding AlCl3/phenetole and TiCl4/H2O and used for cationic polymerization of isobutylene. It was found AlCl3·phenetole/TiCl4·H2O exhibited activities 1.2–3 times higher than those of AlCl3/phenetole, and more than an order of magnitude higher than those of TiCl4/H2O, which indicated a notable synergistic effect produced in the complexed system. In addition, due to the higher activity of AlCl3·phenetole/TiCl4·H2O, lower coinitiator concentration and polymerization temperature, as well as higher monomer concentration were more favored for this complexed initiating system to produce polyisobutylene (PIB) with reasonable molecular weight (Mw) and molecular weight distribution (MWD). Furthermore, high molecular weight polyisobutylene (HPIB) with Mw = 1–3 × 105 g·mol−1 could be successfully produced by the complexed catalyst system at Tp = −60 to −40 °C. As a whole, the high activity as well as the simple preparation procedures of the complexed initiating system offer us a unique approach for the production of HPIB with improved efficiency.

An HF-Nickel-R3Al Catalyst System for Producing High Cis-1,4-Polybutadiene

1972 ◽  
Vol 45 (1) ◽  
pp. 268-277 ◽  
Author(s):  
M. C. Throckmorton ◽  
F. S. Farson
Keyword(s):  
Molecular Weight ◽  
Carbon Black ◽  
High Molecular Weight ◽  
Catalyst Concentration ◽  
Dynamic Properties ◽  
Catalyst System ◽  
Polymerization Temperature

Abstract A relatively new, high cis-1,4-polybutadiene and a novel trialkylaluminumnickel-HF catalyst system have been described. This polybutadiene is unique in that it possesses high tack and has exceptionally good processing qualities; the carbon black-loaded and cured rubber possesses good static and dynamic properties. The catalyst system is very effective for producing high molecular weight rubber, suitable for oil extension, and the molecular weight can be controlled by adjusting 1) HF to R3Al ratio, 2) total catalyst concentration and/or 3) polymerization temperature.

ATRP Synthesis and Characterization of μ,αω-allyl-terminated Macromonomers as Precursors for End-linked Gels and Hydrogels

2003 ◽  
Vol 774 ◽  
Author(s):  
Lucy Vojtova ◽  
Nicholas J. Turro ◽  
Jeffrey T. Koberstein
Keyword(s):  
Molecular Weight ◽  
Monomer Concentration ◽  
Monomer Conversion ◽  
Catalyst System ◽  
Linear Increase ◽  
Butyl Methacrylate ◽  
First Order Kinetics ◽  
Significant Difference ◽  
Ft Ir

AbstractSynthesis of α,ω-allyl-terminated telechelic macromonomers based on poly(tert-butyl methacrylate) (poly(t-BMA)) and poly(methacrylic acid) (poly(MAA)) was studied with the aim of preparing end-linked gels and hydrogels. Low molecular weight α-allyl-terminated poly(t-BMA) macromonomers with narrow polydispersities (Mw/Mn = 1.16) were synthesized via controlled atom transfer radical polymerization (ATRP) using a Cu(I)Br/N,N,N',N',N',N'-hexamethyltriethylenetetraamine catalyst system in conjunction with an allyl-2-bromoisobutyrate as the functional initiator. The polymerizations exhibited a linear increase of molecular weight in direct proportion to the monomer conversion and first-order kinetics with respect to monomer concentration. No significant difference was found between using polar or non-polar solvents (tetrahydrofuran or benzene, respectively). Optimization of reaction conditions to obtain the highest degree of active terminal bromine is discussed. Quenching the ATRP reaction with allyltributyltin yielded α,ω-allyl-terminated poly(t-BMA) macromonomers by replacing the terminal bromine with ω-allyl functional group. Poly(MAA) macromonomers were prepared by deprotection of the tert-butyl group from α,ω-allyl-terminated poly(t-BMA) macromonomers using concentrated trifluoroacetic acid at room temperature. Successful synthetic steps were confirmed by 1H NMR, FT-IR and MALDI-TOF MS analyses. The α,ω-allyl-terminated macromonomers were proven to be candidates for further polymerization by forming end-linked, non-soluble gels.

Polymerization of n-butyl methylacrylate using bis(β- ketoamino)nickel(II)/MAO catalytic systems

e-Polymers ◽  
2008 ◽  
Vol 8 (1) ◽  
Author(s):  
Xiaohui He ◽  
Yiwang Chen ◽  
Yongming Liu ◽  
Muqing Chen ◽  
Shuxian Yu ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Monomer Concentration ◽  
Polymerization Temperature ◽  
Moderate Activity ◽  
Polymerization Time ◽  
Catalytic Systems ◽  
Molecular Weights ◽  
Molar Ratios ◽  
Broad Molecular Weight Distribution ◽  
C Nmr

AbstractThe polymerizations of n-butyl methylacrylate (nBMA) were carried out using bis(β-ketoamino)nickel(II) complexes (Ni[CH3C(O)CHC(NR)CH3]2: R = phenyl, 1; R = naphthyl, 2) in combination with methylaluminoxane (MAO) in toluene. The effect of parameters such as polymerization temperature, Al/Ni molar ratios, polymerization time, and monomer concentration, on catalytic polymerization activity and polymer molecular weights, were examined in detail. Both of the nickel(II) catalytic systems exhibited moderate activity, and produced P(nBMA) with high molecular weight and relatively broad molecular weight distribution (Mw/Mn=2.0~3.0. The obtained polymer has been characterized by means of FTIR, 1H NMR, 13C NMR, DSC, and WAXD technique and was confirmed to be syndio-rich stereospecific P(nBMA).

scholarly journals High Molecular Weight Kininogen Peptides Inhibit the Formation of Kallikrein on Endothelial Cell Surfaces and Subsequent Urokinase-Dependent Plasmin Formation

Blood ◽  
1997 ◽  
Vol 90 (2) ◽  
pp. 690-697 ◽  
Author(s):  
Yingzhang Lin ◽  
Robert B. Harris ◽  
Wuyi Yan ◽  
Keith R. McCrae ◽  
Hong Zhang ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Structural Information ◽  
Umbilical Vein ◽  
High Molecular Weight Kininogen ◽  
Cell Surfaces ◽  
Free System ◽  
Order Of Magnitude ◽  
A Cell ◽  
Umbilical Vein Endothelial Cells

A sequence of 31 amino acids (S565-K595) in domain 6 of the light chain of high molecular weight kininogen (HK) has previously been shown to be responsible for the binding of plasma prekallikrein (PK) or kallikrein. To find effective peptides that might block binding between HK and PK on cell surfaces, a new series of synthetic peptides has now been prepared that incorporates portions of this binding domain sequence. For mapping the minimal sequence within HK, these new peptides were tested for their ability to compete with HK for binding PK in a cell-free system and on human umbilical vein endothelial cells (HUVEC). In the former, at pH 7.4, the kds for binding between kallikrein and either D567-K595, S565-P594, D567-S593, or D567-T591 were all similar to that for the binding of S565-K595 (0.2 to 0.4 μmol/L), but those for the binding of D568-K595, W569-K595, and D567-P589 were an order of magnitude greater (kd = 2 to 5 μmol/L). D567-S586, the shortest chain length of the N- and C-terminal truncation sequences tested, does not effectively compete with kininogen for kallikrein binding (kd = 100 μmol/L). These results imply that D567-T591, a 25-residue peptide (HK25c), contains sufficient structural information for binding kallikrein in solution. D567-T591 also is the minimum structural sequence to block binding of kallikrein to HUVEC-bound HK (IC50 = 50 nmol/L) and to inhibit PK activation to kallikrein on the cell surface (IC50 = 80 nmol/L). In addition, D567-T591 also inhibits the generation of kallikrein-activated urokinase, which activates plasminogen to plasmin (IC50 = 100 nmol/L). Thus, HK-derived peptides may be useful compounds for modulating excessive fibrinolysis and hypotension in sepsis and multiple trauma.

The Effects of Initiating Systems on CPAM Relative Molecular Weight and Strength Properties of Paperboard

2013 ◽  
Vol 821-822 ◽  
pp. 945-948
Author(s):  
Hui Rong Yang ◽  
Chuan Shan Zhao ◽  
Xue Zhang ◽  
Wen Jia Han
Keyword(s):  
Molecular Weight ◽  
Monomer Concentration ◽  
Strength Properties ◽  
Polymerization Temperature ◽  
Initiator Concentration ◽  
Redox Systems ◽  
Aqueous Polymerization ◽  
Relative Molecular Weight

initiator is one of the most important conditions of synthesizing efficient strength agent CPAM. To begin with initiating mechanism, three redox systems of acrylamide aqueous polymerization (NH4)2S2O8/ Na2SO3, K2S2O8/NaHSO3and K2S2O8/Na2S2O4have been studied. The effects of different kinds of initiator, initiator concentration, and monomer concentration as well as polymerization temperature on relative molecular weight and strength effects of CPAM have been investigated. K2S2O8/Na2SO3is the most useful system in synthesizing efficient strength agents.

scholarly journals Ein makroporöses Polyacrylamid für immunologische Diffusionstechniken / Macroporous Polyacrylamide, its Use for Immunological Diffusion Techniques

1972 ◽  
Vol 27 (6) ◽  
pp. 683-688 ◽  
Author(s):  
Helmut Determann ◽  
Axel Walch
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Monomer Concentration ◽  
Agarose Gels ◽  
Γ Globulins ◽  
Sample Application ◽  
Total Monomer Concentration ◽  
High Molecular Weight Proteins ◽  
High Concentrations

Gel layers of crosslinked polyacrylamide with different porosities were synthesized and their properties compared. At high concentrations of bifunctional monomers macroporous gels were formed, one of which (total monomer concentration 14%, methylene-bis-acrylamide 40%) permitted even high molecular weight proteins (e. g. γ-globulins) to diffuse more readily than in 2 per cent agar or agarose gels. Different immunological techniques were modified for application with this polymer. It offers advantages especially with respect to porosity, storability and sample application for quantitative diffusion techniques.

Synthesis of Ultra-High Molecular Weight Polyacrylonitrile (UHMWPAN) by Aqueous Suspension Polymerization

2015 ◽  
Vol 1120-1121 ◽  
pp. 615-619
Author(s):  
Hui Yu Jiang ◽  
Mei Hua Zhou ◽  
Ding Pan
Keyword(s):  
Molecular Weight ◽  
Suspension Polymerization ◽  
Aqueous Suspension ◽  
Average Molecular Weight ◽  
Monomer Concentration ◽  
Polymerization Process ◽  
Polymerization Temperature ◽  
Different Temperatures ◽  
Total Monomer Concentration ◽  
Ultra High Molecular Weight

Acrylonitrile (AN) and itaconic acid (IA) were used to synthesize UHMWPAN by aqueous suspension method with 2,2’-azobisisobutyronitrile (AIBN) as the initiator and polyvinylalcohol (PVA) as the disperser at different temperatures (55°C~75°C) for different timings (1.0h~3.0h). The usage amounts of AN, IA, AIBN and PVA were also technical polymerization parameters used to obtain the optimal polymerization process. We found that the conversion and the viscosity average molecular weight both achieved the optimum levels when the conditions were as follows: the total monomer concentration (21wt%), the monomer ratio (AN: IA=98:2), the usage amount of the initiator (AIBN, 0.01wt%), the usage amount of the disperser (PVA, 0.1wt%), the polymerization temperature (70°C) and the polymerization time (2h).

Sign in / Sign up

Export Citation Format

Share Document