scholarly journals Hydrolytic Degradation of Comb-Like Graft Poly (Lactide-co-Trimethylene Carbonate): The Role of Comonomer Compositions and Sequences

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2024
Author(s):  
Xuefei Leng ◽  
Wenwen Zhang ◽  
Yiying Wang ◽  
Yanshai Wang ◽  
Xiaoqing Li ◽  
...  
Keyword(s):  
Block Copolymers ◽  
Hydrolytic Degradation ◽  
Gel Permeation Chromatography ◽  
Random Copolymers ◽  
Degradation Behavior ◽  
Weight Retention ◽  
Trimethylene Carbonate ◽  
Degradation Rates ◽  
Degradation Behaviors ◽  
Property Changes

The effect of sequence on copolymer properties is rarely studied, especially the degradation behavior of the biomaterials. A series of linear-comb block, gradient, random copolymers were successfully achieved using hydroxylated polybutadiene as the macroinitiator by simple ring-opening polymerization of l-lactide (l-LA) and 1,3-trimethylene carbonate (TMC). The hydrolytic degradation behaviors of the copolymers were systemically evaluated by using nuclear magnetic resonance (NMR), gel permeation chromatography (GPC), differential scanning calorimeter (DSC), and scanning electron microscopy (SEM) to illustrate the influences of comonomer compositions and sequence structures. The linear-comb block copolymers (lcP(TMC-b-LLA)) with different compositions had different degradation rates, which increased with l-LA content. Thermal property changes were observed with decreased Tm and increased ΔHm in all block copolymers during the degradation. To combine different sequence structures, unique degradation behaviors were observed for the linear-comb block, gradient and random copolymers even with similar comonomer composition. The degradation rates of linear-comb PLLA-gradient-PTMC (lcP(LLA-grad-TMC)) and linear-comb PLLA-random-PTMC (lcP(LLA-ran-TMC)) were accelerated due to the loss of regularity and crystallinity, resulting in a remarkable decrease on weight retention and molar mass. The hydrolysis degradation rate increased in the order lcP(TMC-b-LLA), lcP(LLA-ran-TMC), lcP(LLA-grad-TMC). Therefore, the hydrolytic degradation behavior of comb-like graft copolymers depends on both the compositions and the sequences dramatically.

scholarly journals Synthesis, Properties, and In Vitro Hydrolytic Degradation of Poly(d,l-lactide-co-glycolide-co-ε-caprolactone)

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Yixiu Liu ◽  
Xizhuang Bai ◽  
A. Liang
Keyword(s):  
Ring Opening ◽  
Degradation Products ◽  
Hydrolytic Degradation ◽  
Ring Opening Polymerization ◽  
Random Copolymers ◽  
Thermal And Mechanical Properties ◽  
Degradation Rates ◽  
Synthesis Properties ◽  
Acidic Degradation

Random copolymers of poly(d,l-lactide-co-glycolide-co-ε-caprolactone) (PLGC) were synthesized by the ring-opening polymerization of d,l-lactide (DLLA), glycolide (GA), andε-caprolactone (CL). The effects of CL on the copolymers were evaluated to prepare suitable copolymers with controlled properties. Our results showed that the CL content significantly influenced the thermal and mechanical properties of the copolymers and that the CL content in compositions could be altered to control properties of random copolymers. The in vitro hydrolytic degradation of the resulting implants showed that the degradation rate of PLGC was lower than that of PLGA, which could markedly reduce acidic degradation products. Finally, we demonstrated that higher CL contents in compositions slowed degradation rates.

scholarly journals Synthetic Approaches for Poly(Phenylene) Block Copolymers via Nickel Coupling Reaction for Fuel Cell Applications

Polymers ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1614 ◽  
Author(s):  
Adam F. Nugraha ◽  
Songmi Kim ◽  
Farid Wijaya ◽  
Byungchan Bae ◽  
Dongwon Shin
Keyword(s):  
Block Copolymers ◽  
Cost Savings ◽  
Coupling Reaction ◽  
Chloride Ion ◽  
Gel Permeation Chromatography ◽  
Nickel Catalysts ◽  
Degree Of Polymerization ◽  
Random Copolymers ◽  
High Molecular Weight Polymer ◽  
Molecular Weight Polymer

Several methods to synthesize poly(phenylene) block copolymers through the nickel coupling reaction were attempted to reduce the use of expensive nickel catalysts in polymerization. The model reaction for poly(phenylene) having different types of dichlorobenzene derivative monomers illustrated the potential use of cost-effective catalysts, such as NiBr2 and NiCl2, as alternatives to more expensive catalysts (e.g., bis(1,5-cyclooctadiene)nickel(0) (Ni(COD)2)). By catalyzing the polymerization of multi-block poly(phenylene) with NiBr2 and NiCl2, random copolymers with similar molecular weights could be prepared. However, these catalysts did not result in a high-molecular-weight polymer, limiting their wide scale application. Further, the amount of Ni(COD)2 could be reduced in this study by approximately 50% to synthesize poly(phenylene) multi-block copolymers, representing significant cost savings. Gel permeation chromatography and nuclear magnetic resonance results showed that the degree of polymerization and ion exchange capacity of the copolymers were almost the same as those achieved through conventional polymerization using 2.5 times as much Ni(COD)2. The flexible quaternized membrane showed higher chloride ion conductivity than commercial Fumatech membranes with comparable water uptake and promising chemical stability.

Redox-active polymer-nanoparticle hybrid materials

2000 ◽  
Vol 72 (1-2) ◽  
pp. 67-72 ◽  
Author(s):  
Keith J. Watson ◽  
Jin Zhu ◽  
SonBinh T. Nguyen ◽  
Chad A. Mirkin
Keyword(s):  
Gold Nanoparticles ◽  
Block Copolymers ◽  
Hybrid Materials ◽  
Ring Opening ◽  
Gel Permeation Chromatography ◽  
Polymer Chains ◽  
Electrochemical Studies ◽  
Redox Active ◽  
Gel Permeation ◽  
Current Rectification

Ring-opening metathesis polymerization was used to modify organic soluble gold nanoparticles with redox-active polymers. A gel-permeation chromatography study revealed that each nanoparticle is modified with approximately 11 polymer chains. Electrochemical studies of nanoparticles modified with block copolymers of two different redox-active groups revealed that each monomer is electrochemically accessible, while no current rectification was observed.

Study of block copolymers by gel-permeation chromatography

1982 ◽  
Vol 24 (6) ◽  
pp. 1512-1517 ◽  
Author(s):  
V.V. Nesterov ◽  
V.D. Krasikov ◽  
Ye.V. Chubarova ◽  
B.G. Belen'kii
Keyword(s):  
Block Copolymers ◽  
Gel Permeation Chromatography ◽  
Gel Permeation

scholarly journals Synthesis of Poly(methyl methacrylate)-b-poly(N-isopropylacrylamide) Block Copolymer by Redox Polymerization and Atom Transfer Radical Polymerization

2018 ◽  
Vol 18 (3) ◽  
pp. 537 ◽  
Author(s):  
Melahat Göktaş ◽  
Guodong Deng
Keyword(s):  
Block Copolymers ◽  
Methyl Methacrylate ◽  
Atom Transfer Radical Polymerization ◽  
Radical Polymerization ◽  
Gel Permeation Chromatography ◽  
High Yield ◽  
Resonance Spectroscopy ◽  
Atom Transfer ◽  
Poly Methyl Methacrylate ◽  
Redox Polymerization

Poly(methyl methacrylate)-b-poly(N-isopropylacrylamide) [PMMA-b-PNIPAM] block copolymers were obtained by a combination of redox polymerization and atom transfer radical polymerization (ATRP) methods in two steps. For this purpose, PMMA macroinitator (ATRP-macroinitiator) was synthesized by redox polymerization of methyl methacrylate and 3-bromo-1-propanol using Ce(NH4)2(NO3)6 as a catalyst. The synthesis of PMMA-b-PNIPAM block copolymers was carried out by means of ATRP of ATRP-macroinitiator and NIPAM at 60 °C. The block copolymers were obtained in high yield and high molecular weight. The characterization of products was accomplished by using multi instruments and methods such as nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, gel permeation chromatography, and thermogravimetric analysis.

scholarly journals Thermoreversible poly(trimethylene carbonate)-based block copolymers containing reactive furfuryl groups via sequential ROP and ATRP

2021 ◽  
pp. 110873
Author(s):  
Aarón Pérez ◽  
Gerard Lligadas ◽  
Juan Carlos Ronda ◽  
Marina Galià ◽  
Virginia Cádiz
Keyword(s):  
Block Copolymers ◽  
Trimethylene Carbonate

Microporous Bio-Membrane Materials Based on High Molecular Weight Polylactide and Low Molecular Weight Poly(ethylene glycol)

2012 ◽  
Vol 567 ◽  
pp. 123-126
Author(s):  
Teng Fei Shen ◽  
Man Geng Lu ◽  
Li Yan Liang
Keyword(s):  
Molecular Weight ◽  
Ethylene Glycol ◽  
High Weight ◽  
Low Molecular Weight ◽  
Poly Ethylene Glycol ◽  
Degradation Rates ◽  
Degradation Behaviors ◽  
The Mean ◽  
Poly Ethylene ◽  
Lower Glass Transition Temperature

In this work, microporous membrane biomaterials based on high weight molecular polylactide (PLA) and low molecular weight poly(ethylene glycol) (PEG) using rapid solvent evaporation method were prepared and investigated. The effect of PEG segments added on the thermal and degradation behaviors was studied. According to the results, produced PLA/PEG biomaterial has lower glass transition temperature (Tg)in comparison with neat PLA. It was also found that the degradation rates of the PLA/PEG biomaterials were significantly increased with adding of PEG, which explained by increasing hydrophilic groups. For better porous fixation, CL-blocked polyisocyanate (CL-bp), which was synthesized from reaction of isophorone diisocyanate (IPDI) with dimethylol propionic acid (DMPA) and Trimethylolpropane (TMP) followed by addition of caprolactam (CL), were introduced. The microporous forms were observed by the scanning electron microscope (SEM), which showed the mean diameters of prepared PLA/PEG microporous were around 10μm.

Research on Degradation Behavior of Airborne Rubber Products

2012 ◽  
Vol 466-467 ◽  
pp. 127-131
Author(s):  
Xiao Jie Zhang ◽  
Tong Min Jiang ◽  
Hua Luo ◽  
Xiao Rui Zhang
Keyword(s):  
Detailed Analysis ◽  
Failure Mechanism ◽  
Aging Process ◽  
Degradation Behavior ◽  
Degradation Model ◽  
Electronic Products ◽  
Rubber Seal ◽  
Degradation Behaviors ◽  
Conducting Research ◽  
And Storage

Due to the complex working and storage environment for airplanes, the consumptive failures of airborne products are unavoidable. Aiming at the problem that degradation behaviors that cause this kind of failures are frequently neglected, based on the concept of degradation for airborne products, a new method of conducting research that treats aging process as a critical degradation behavior is presented. According to the characteristics of airborne mechano-electronic products, steering engine is defined as a critical airplane airborne mechano-electronic product. Through detailed analysis of the vulnerable area of steering engine, the failure mechanism of aging of steering engine rubber seal is discussed. The degradation model of steering engine rubber seal is presented. Finally, feasibility of the method that replaces the research of degradation behavior of the airborne mechano-electronic products with that of aging is verified.

scholarly journals Synthesis of Fluorinated Amphiphilic Block Copolymers Based on PEGMA, HEMA, and MMA via ATRP and CuAAC Click Chemistry

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Fatime Eren Erol ◽  
Deniz Sinirlioglu ◽  
Sedat Cosgun ◽  
Ali Ekrem Muftuoglu
Keyword(s):  
Block Copolymer ◽  
Block Copolymers ◽  
Amphiphilic Block Copolymers ◽  
Random Copolymers ◽  
Side Chain ◽  
Dipolar Cycloaddition ◽  
Controlled Synthesis ◽  
H Nmr ◽  
Ft Ir ◽  
Click Coupling

Synthesis of fluorinated amphiphilic block copolymers via atom transfer radical polymerization (ATRP) and Cu(I) catalyzed Huisgen 1,3-dipolar cycloaddition (CuAAC) was demonstrated. First, a PEGMA and MMA based block copolymer carrying multiple side-chain acetylene moieties on the hydrophobic segment for postfunctionalization was carried out. This involves the synthesis of a series of P(HEMA-co-MMA) random copolymers to be employed as macroinitiators in the controlled synthesis of P(HEMA-co-MMA)-block-PPEGMA block copolymers by using ATRP, followed by a modification step on the hydroxyl side groups of HEMA via Steglich esterification to afford propargyl side-functional polymer, alkyne-P(HEMA-co-MMA)-block-PPEGMA. Finally, click coupling between side-chain acetylene functionalities and 2,3,4,5,6-pentafluorobenzyl azide yielded fluorinated amphiphilic block copolymers. The obtained polymers were structurally characterized by1H-NMR,19F-NMR, FT-IR, and GPC. Their thermal characterizations were performed using DSC and TGA.

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