Polymerization of Lactide Catalyzed by Diketiminato Iron (II) Alkoxide Complex

2011 ◽  
Vol 393-395 ◽  
pp. 1346-1349
Author(s):  
Yong Fei Li ◽  
Qin Wu ◽  
Mei Li Gao
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Reaction Temperature ◽  
Iron Complex ◽  
Feed Ratio ◽  
Moderate Activity ◽  
Monomer Feed ◽  
Monomer Feed Ratio ◽  
Lactide Polymerization

Lactide polymerization were carried out by using diketiminato iron (II) alkoxide complexes HC(C(CH3)N-2,6-iPr2C6H3)2FeOiPr as catalyst. The iron (II) alkoxide complex bearing bulky isopropyl ortho substituents showed moderate activity for the rac-lactide polymerization, and gave the polylactide (PLA) with high molecular weight. In the microstructures of polymers generated with the iron (II) catalyst, no stereoslective polymerization of rac-lactide has been detected. Results have shown that the conversion of lactide depend on the iron complex/monomer feed ratio and the reaction temperature.

Synthesis of Stereoregular Polylactide

2011 ◽  
Vol 391-392 ◽  
pp. 107-110
Author(s):  
Yong Fei Li ◽  
Qin Wu ◽  
Mei Li Gao
Keyword(s):  
Reaction Temperature ◽  
Feed Ratio ◽  
Moderate Activity ◽  
Microstructural Study ◽  
Aluminum Alkoxide ◽  
Lactide Polymerization

The paper studied polymerization of rac-lactide catalyzed by a diketiminato aluminum alkoxide complex. The aluminum alkoxide complex bearing bulky isopropyl ortho substituents showed moderate activity for the rac-lactide polymerization. Microstructural study of polymer generated with the aluminum catalyst reveals that syndiotactic polylactide were produced. Results have shown that the conversion of lactide depend on the monomer/catalyst feed ratio and the reaction temperature.

Synthesis, characterisation and properties of aramid copolymers prepared from AB and AB2 monomers

e-Polymers ◽  
2003 ◽  
Vol 3 (1) ◽  
Author(s):  
Orietta Monticelli ◽  
Stefano Fiori ◽  
Alberto Mariani ◽  
Saverio Russo ◽  
Hartmut Komber
Keyword(s):  
Liquid Crystalline ◽  
Reaction Medium ◽  
Aromatic Polyamide ◽  
Degree Of Crystallinity ◽  
Feed Ratio ◽  
Structure Evolution ◽  
Monomer Composition ◽  
Degradation Temperature ◽  
Monomer Feed ◽  
Monomer Feed Ratio

Abstract Aromatic polyamide (aramid) copolymers having a highly branched architecture were prepared by direct polycondensation of an AB2 monomer (5-(4-aminobenzoylamino) isophthalic acid) with an AB monomer (N-(4-aminophenyl)terephthalamic acid). Two synthetic routes have been followed for copolymer preparation, differing from each other in the overall monomer content and the type of salts added to the reaction medium (LiCl or LiCl + CaCl2). Otherwise, both methods used the same conditions and the same condensing agent (triphenyl phosphite). The feed ratio of the monomers affected the copolymer solubility in aprotic polar solvents such as N,N-dimethylformamide, N-methylpyrrolidone and dimethyl sulfoxide. Only high AB2/AB monomer ratios allowed obtaining completely soluble polymers in the above media. Also copolymer intrinsic viscosity was influenced by that ratio as well as by the polymerisation routes. IR measurements gave an indication of polymer structure evolution as a function of the monomer feed ratio, while 1H NMR experiments verified the actual monomer composition in the synthesized polymers. The monomer feed ratio turned out to influence polymer properties, such as degree of crystallinity, thermal degradation temperature and liquid crystalline behaviour. Some of the characterisation techniques we used (1H and 31P NMR, IR, SEM-EDS) revealed the presence of phosphorus derivatives in the copolymers, despite extensive sample purification. This presence is coming from derivatives of the condensing agent, and is directly related to the content of AB2-type structures present in the copolymers.

scholarly journals Catalytic Degradation of Chitosan by Supported Heteropoly Acids in Heterogeneous Systems

Catalysts ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1078
Author(s):  
Hang Zhang ◽  
Zhipeng Ma ◽  
Yunpeng Min ◽  
Huiru Wang ◽  
Ru Zhang ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Molecular Weight ◽  
Catalytic Activity ◽  
Activated Carbon ◽  
Reaction Time ◽  
High Molecular Weight ◽  
Reaction Temperature ◽  
Water Soluble ◽  
High Catalytic Activity ◽  
High Molecular Weight Chitosan

Several kinds of composite materials with phosphotungstic acid (PTA) as the catalyst were prepared with activated carbon as support, and their structures were characterized. According to the Box–Behnken central combination principle, the mathematical model of the heterogeneous system is established. Based on the single-factor experiments, the reaction temperature, the reaction time, the amount of hydrogen peroxide and the loading capacity of PTA were selected as the influencing factors to study the catalyzed oxidation of hydrogen peroxide and degradation of high molecular weight chitosan. The results of IR showed that the catalyst had a Keggin structure. The results of the mercury intrusion test showed that the pore structure of the supported PTA catalyst did not change significantly, and with the increase of PTA loading, the porosity and pore volume decreased regularly, which indicated that PTA molecules had been absorbed and filled into the pore of activated carbon. The results of Response Surface Design (RSD) showed that the optimum reaction conditions of supported PTA catalysts for oxidative degradation of high molecular weight chitosan by hydrogen peroxide were as follows: reaction temperature was 70 ℃, reaction time was 3.0 h, the ratio of hydrogen peroxide to chitosan was 2.4 and the catalyst loading was 30%. Under these conditions, the yield and molecular weight of water-soluble chitosan were 62.8% and 1290 Da, respectively. The supported PTA catalyst maintained high catalytic activity after three reuses, which indicated that the supported PTA catalyst had excellent catalytic activity and stable performance compared with the PTA catalyst.

The growth and chemical structure of thin photonic films formed from plasma copolymerization: I. Effect of monomer feed ratio

Polymer ◽  
2004 ◽  
Vol 45 (25) ◽  
pp. 8475-8483 ◽  
Author(s):  
H. Jiang ◽  
J.T. Grant ◽  
S. Tullis ◽  
K. Eyink ◽  
P. Fleitz ◽  
...  
Keyword(s):  
Chemical Structure ◽  
Feed Ratio ◽  
Monomer Feed ◽  
Plasma Copolymerization ◽  
Monomer Feed Ratio

Self-doped N-4-sulfopropylaniline–3, 4-ethylenedioxythiophene copolymers

2016 ◽  
Vol 29 (8) ◽  
pp. 976-983 ◽  
Author(s):  
Isao Yamaguchi ◽  
Masaru Ito
Keyword(s):  
Electrical Conductivity ◽  
Electrochemical Oxidation ◽  
Visible Spectrum ◽  
Ammonium Persulfate ◽  
Feed Ratio ◽  
Molar Ratios ◽  
Monomer Feed ◽  
Monomer Feed Ratio

Polymerization of N-4-sulfopropylaniline with 3,4-ethylenedioxythiophene (EDOT) in several molar ratios using ammonium persulfate yielded copolymers (PPrSO3H) consisting of N-4-sulfopropylaminophenylene (unit A) and 3,4-ethylenedioxythiophene-2,5-diyl (unit B). The corresponding copolymers (PBu) consisting of N-butylaminophenylene (unit C) and unit B were synthesized by the reaction of N-butylaniline and EDOT. The content of units A, B, and C in the copolymers depended on the monomer feed ratio. The ultraviolet–visible spectrum of PPrSO3H exhibited absorption peaks at approximately 420 nm and above 850 nm assignable, respectively, to polaron and bipolaron bands. The copolymers were subjected to electrochemical oxidation, which was dependent on the contents of units A and C. The electrical conductivity of PPrSO3H was found to be higher than that of PBu.

scholarly journals The First Synthesis of Periodic and Alternating Glycopolymers by RAFT Polymerization: A Novel Synthetic Pathway for Glycosaminoglycan Mimics

Polymers ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 70 ◽  
Author(s):  
Masahiko Minoda ◽  
Tomomi Otsubo ◽  
Yohei Yamamoto ◽  
Jianxin Zhao ◽  
Yoshitomo Honda ◽  
...  
Keyword(s):  
Chain Transfer ◽  
Binding Assay ◽  
Raft Polymerization ◽  
Lectin Binding ◽  
Feed Ratio ◽  
Controlled Synthesis ◽  
Reversible Addition ◽  
Monomer Feed ◽  
Polymerization Condition ◽  
Monomer Feed Ratio

This study concerned the controlled synthesis of periodic glycopolymers by reversible addition-fragmentation chain transfer (RAFT) copolymerization. To this end, maltose- and lactose-substituted vinyl ethers (MalVE and LacVE, respectively) and maltose-substituted maleimide (MalMI) were newly synthesized. RAFT copolymerization of MalVE and ethyl maleimide (EtMI) (monomer feed ratio: MalVE:EtMI = 1:1) afforded periodic glycopolymers (poly(MalVE-co-EtMI)) consisting of major parts of alternating structure (-(MalVE-EtMI)n-) and a small part of consecutive sequences of EtMI (–EtMI-EtMI-). Occurrence of the latter sequences was caused by the homopolymerizability of maleimide under the present polymerization condition, and the formation of the consecutive sequences of EtMI was successfully suppressed by varying the monomer feed ratio. RAFT copolymerization of LacVE and EtMI was also found to proceed and similarly yielded periodic glycopolymers (poly(LacVE-co-EtMI)). Moreover, RAFT copolymerization of LacVE and MalMI (monomer feed ratio: LacVE:MalMI = 1:1) was performed to give copolymers (poly(LacVE-co-MalMI)) having composition ratio of LacVE/MalMI ≈ 36/64. The resultant periodic glycopolymers poly(MalVE-co-EtMI) and poly(LacVE-co-EtMI) were subjected to lectin binding assay using concanavalin A and peanut agglutinin, exhibiting the glycocluster effect. Moreover, these glycopolymers obtained from the copolymerization of VE and MI were found to be non-cytotoxic.

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