Chain Extension of Poly(butylene adipate) with 2,2’-(1,4- Phenylene)-bis(2-oxazoline)

Low molecular weight poly(butylene adipate) (PBA) was synthesized by melt polycondensation. The chain extension of the prepolymers was carried out using 2,2’-(1,4-phenylene)-bis(2-oxazoline) (PBOX) as chain-extender. The influencing factors including reaction temperature, oxazoline/-COOH molar ratio, and the molecular weight of prepolymers were studied. At the optimal chain-extending condition, PBA with Mn of 38583 and Mw of 125497 was prepared. The structure of the chain-extended PBA was also characterized by the FTIR and 1H NMR.

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Poly(lactic Acid): A Versatile Biobased Polymer for the Future with Multifunctional Properties—From Monomer Synthesis, Polymerization Techniques and Molecular Weight Increase to PLA Applications

Polymers ◽

10.3390/polym13111822 ◽

2021 ◽

Vol 13 (11) ◽

pp. 1822

Author(s):

Evangelia Balla ◽

Vasileios Daniilidis ◽

Georgia Karlioti ◽

Theocharis Kalamas ◽

Myrika Stefanidou ◽

...

Keyword(s):

Molecular Weight ◽

Lactic Acid ◽

Chain Extension ◽

Poly Lactic Acid ◽

Plastic Pollution ◽

Practical Applications ◽

Decomposition Reactions ◽

Melt Polycondensation ◽

Polymerization Conditions ◽

Molecular Weight Increase

Environmental problems, such as global warming and plastic pollution have forced researchers to investigate alternatives for conventional plastics. Poly(lactic acid) (PLA), one of the well-known eco-friendly biodegradables and biobased polyesters, has been studied extensively and is considered to be a promising substitute to petroleum-based polymers. This review gives an inclusive overview of the current research of lactic acid and lactide dimer techniques along with the production of PLA from its monomers. Melt polycondensation as well as ring opening polymerization techniques are discussed, and the effect of various catalysts and polymerization conditions is thoroughly presented. Reaction mechanisms are also reviewed. However, due to the competitive decomposition reactions, in the most cases low or medium molecular weight (MW) of PLA, not exceeding 20,000–50,000 g/mol, are prepared. For this reason, additional procedures such as solid state polycondensation (SSP) and chain extension (CE) reaching MW ranging from 80,000 up to 250,000 g/mol are extensively investigated here. Lastly, numerous practical applications of PLA in various fields of industry, technical challenges and limitations of PLA use as well as its future perspectives are also reported in this review.

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Low-Molecular-Weight Polyethyleneimine Grafted Polythiophene for Efficient siRNA Delivery

BioMed Research International ◽

10.1155/2015/406389 ◽

2015 ◽

Vol 2015 ◽

pp. 1-9 ◽

Cited By ~ 4

Author(s):

Pan He ◽

Kyoji Hagiwara ◽

Hui Chong ◽

Hsiao-hua Yu ◽

Yoshihiro Ito

Keyword(s):

Molecular Weight ◽

Sirna Delivery ◽

Fluorescent Microscopy ◽

Molar Ratio ◽

Low Molecular Weight ◽

Label Free ◽

Endosomal Membrane ◽

Cationic Copolymers ◽

Interfering Rna

Owing to its hydrophilicity, negative charge, small size, and labile degradation by endogenous nucleases, small interfering RNA (siRNA) delivery must be achieved by a carrier system. In this study, cationic copolymers composed of low-molecular-weight polyethylenimine and polythiophenes were synthesized and evaluated as novel self-tracking siRNA delivery vectors. The concept underlying the design of these copolymers is that hydrophobicity and rigidity of polythiophenes should enhance the transport of siRNA across the cell membrane and endosomal membrane. A gel retardation assay showed that the nanosized complexes formed between the copolymers and siRNA were stable even at a molar ratio of 1 : 2. The high cellular uptake (>80%) and localization of the copolymer vectors inside the cells were easily analyzed by tracking the fluorescence of polythiophene using fluorescent microscopy and cytometry. Anin vitroluciferase knockdown (KD) assay in A549-luc cells demonstrated that the siRNA complexes with more hydrophobic copolymers achieved a higher KD efficiency of 52.8% without notable cytotoxicity, indicating protein-specific KD activity rather than solely the cytotoxicity of the materials. Our polythiophene copolymers should serve as novel, efficient, low cell toxicity, and label-free siRNA delivery systems.

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Synthesis of polylactic acid-diol (PLA-diol) from lactic acid and 1,4-butanediol

Science and Technology Development Journal ◽

10.32508/stdj.v19i4.593 ◽

2016 ◽

Vol 19 (4) ◽

pp. 58-65

Author(s):

Ha Thi Thai La

Keyword(s):

Molecular Weight ◽

Lactic Acid ◽

Polyethylene Glycol ◽

1H Nmr ◽

Biodegradable Polymer ◽

Average Molecular Weight ◽

Chain Extension ◽

Structure And Properties ◽

Chain Reaction ◽

A Chain

In this research, the PLA-diol were synthesized from lactic acid (LA) and 1.4 butanediols (BD) with a tin octoate Sn(Oct)2 catalyst at a temperature of 180 °C and the pressure 5 mmHg. The structure and properties of PLA-diol are analyzed by the following methods: GPC, 1H-NMR and DSC. As a result, with the change in the content of Sn (Oct)2 from 0.1 to 1.0%, the molecular weight Mn of PLA - diol increased gradually from 4.119,2 to 7.359,6 g / mol . In addition, the BD content increased from 2.0% to 5.0%, the average molecular weight of the product decreased gradually from 7.536,9 g / mol to 4.735 g / mol, respectively. This change will affect the ability to use PLA-diol in the next denaturation research to apply in the field of biodegradable polymer such as copolymer with polyurethane, copolymer with polyethylene glycol diacid, or chain extension with other polymer in a chain reaction,...

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Biodiesel fuel synthesis by interesterification of triglycerides with carboxylate esters of low molecular weight

Reviews in Chemical Engineering ◽

10.1515/revce-2018-0083 ◽

2019 ◽

Vol 0 (0) ◽

Author(s):

Egle Sendzikiene ◽

Violeta Makareviciene

Keyword(s):

Molecular Weight ◽

Raw Materials ◽

Fatty Acid Esters ◽

Biodiesel Production ◽

Molar Ratio ◽

Transport Sector ◽

Biodiesel Fuel ◽

Low Molecular Weight ◽

Raw Glycerol ◽

Biodiesel Synthesis

Abstract The ever-increasing environmental pollution from greenhouse gases motivates the search for methods to reduce it. One such method is the use of biodiesel fuels in the transport sector. Conventional biodiesel production generates up to 10% of a by-product, raw glycerol, whose amount continues to increase as biodiesel production volumes expand, but its demand remains limited. Recently, options have been analysed to replace the triglyceride transesterification process generally used in biodiesel production with an interesterification process that does not generate raw glycerol, instead yielding triacylglycerol that can be directly used as fuel for diesel engines by mixing with fatty acid esters. Additionally, triacylglycerol improves the low-temperature properties of fuel. The present article discusses triglyceride interesterification processes using various carboxylate esters of low molecular weight. Information is provided on raw materials that can be subjected to interesterification for biodiesel synthesis. The possible applications of chemical and enzymatic catalysis for triglyceride interesterification are discussed, and the influence of the catalyst amount, molar ratio of reactants, temperature and process duration on the effectiveness of interesterification is examined. The conditions and effectiveness of noncatalytic interesterification are also discussed in the article. Qualitative indicators of the products obtained and their conformity to the requirements of the European standard for biodiesel fuel are discussed.

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Effect of reaction temperature and reaction time on the preparation of low-molecular-weight chitosan using phosphoric acid

Carbohydrate Polymers ◽

10.1016/s0144-8617(02)00026-7 ◽

2002 ◽

Vol 49 (4) ◽

pp. 393-396 ◽

Cited By ~ 68

Author(s):

Z Jia

Keyword(s):

Molecular Weight ◽

Reaction Time ◽

Phosphoric Acid ◽

Reaction Temperature ◽

Low Molecular Weight ◽

Low Molecular Weight Chitosan

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Study on Mechanical Properties of Polyurethane Elastomers for Drum Scraper

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.284-286.2384 ◽

2011 ◽

Vol 284-286 ◽

pp. 2384-2387

Author(s):

Jin Cui Zhang ◽

Xi Jun Liu ◽

Tie Ning Ma

Keyword(s):

Mechanical Properties ◽

Chain Extender ◽

Glycol Ether ◽

Toluene Diisocyanate ◽

Chain Extension ◽

Molar Ratio ◽

Casting Method ◽

Polyurethane Elastomers ◽

Application Requirements

Polyurethane elastomers (PUE) were prepared by casting method using the prepolymer and the chain extender. In here, the prepolymer synthesized by using poly(tetramethylene glycol ether) (PTMG) and toluene diisocyanate (TDI), the chain extender was a mixture of 3,5-dimetylthio toluene diamine (E-300) and triethanolamine. The effects of the NCO concentration in prepolymer, the molar ratio of E-300/triethanolamine, and the chain extension coefficient of NCO/NH2 on the mechanical properties of the prepared PUE were studied. The results showed that the prepared PUE possesses excellent mechanical properties which can meet the drum scraper’s application requirements when the NCO concentration in prepolymer was 5.06% and the molar ratio of composite chain extender was 0.92/0.08.

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Living free radical polymerization of styrene with 2-cyanoprop-2-yl dithionaphthalate as RAFT agent

e-Polymers ◽

10.1515/epoly.2003.3.1.576 ◽

2003 ◽

Vol 3 (1) ◽

Author(s):

Zhu Jian ◽

Zhu Xiulin ◽

Zhou Di ◽

Chen Jianying

Keyword(s):

Molecular Weight ◽

Reaction Temperature ◽

Raft Polymerization ◽

Monomer Concentration ◽

Gel Permeation Chromatography ◽

Monomer Conversion ◽

Bulk Polymerization ◽

Polymerization Rate ◽

Chain Extension ◽

Raft Agent

Abstract The reversible addition-fragmentation chain transfer (RAFT) bulk polymerization of styrene was studied using 2-cyanoprop-2-yl dithionaphthalate (CPDN) as RAFT agent in the presence or absence of 2,2’-azoisobutyronitrile (AIBN). The results of both thermally and AIBN-initiated styrene (St) polymerizations show that St can be polymerized in a controlled way using CPDN as RAFT agent; i.e., the polymerization rate is first order with respect to monomer concentration, and molecular weight increases linearly with monomer conversion. The molecular weights obtained from gel permeation chromatography are close to the theoretical values and molecular weight distributions are relatively narrow (Mw/Mn < 1.2). It is confirmed by chain extension reaction that the polymer prepared via RAFT polymerization can be used as a macroRAFT agent. The effects of reaction temperature and mole ratios [St]0/[CPDN]0/[AIBN]0 on the polymerization were investigated. The results indicate that the reaction temperature has a positive effect on the polymerization rate, but little effect on molecular weight and molecular weight distribution, and the optimum mole ratios were found to be [CPDN]0/[AIBN]0 > 4/3 and [St]0/[CPDN]0 < 800.

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Synthesis and Application of a Modifier to Enhance General Properties of the Polar Wood

Materials Science Forum ◽

10.4028/www.scientific.net/msf.675-677.399 ◽

2011 ◽

Vol 675-677 ◽

pp. 399-402

Author(s):

Yi Fei Jiang ◽

Guo Feng Wu ◽

Hao Zhang ◽

Ping Qu ◽

Jun Wen Pu

Keyword(s):

Molecular Weight ◽

Bending Strength ◽

Treated Wood ◽

High Strength ◽

High Reactivity ◽

Degree Of Crystallinity ◽

Molar Ratio ◽

Low Molecular Weight ◽

Impregnation Method ◽

Resin Impregnation

A preparation method of modifier with low molecular weight and high reactivity is presented. This modifier （called KFK in lab）can impregnate into polar wood along trachea from the ends with pressurized impregnation method. In the following heating and pressing processes of the polar wood, the KFK polymerizes, and it enhances stability and strength of the wood. It showed that the favorable conditions for synthetic reaction of the KFK are: molar ratio of U and F, 1:1; reaction temperature, 20°C; reaction time, 3 hours; dosage of ignition primer A: 5%. Results from test showed the degree of crystallinity tested by XRD were 30%, 32% in different dosage of the modifier. Utilizing a combination of low molecular weight resin impregnation and pressing resulted in a density increase of KFK resin-treated wood from 0.214 to 0.268g/cm3. At the same time, the Young’s modulus and bending strength increased from 1.407GPa to 1.759GPa and 64MPa to 74.5MPa, respectively. It can be concluded that the effective utilization of KFK resin impregnated in polar wood is a promising technique for the production of high-strength in the drying and pressing processing.

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