Synthesis of High Molecular Weight Poly(L-Lactic Acid)s by Direct Polycondensation with Organic Acids as Catalyst

2018 ◽  
Vol 773 ◽  
pp. 25-29
Author(s):  
Sung Yeon Hwang ◽  
Dong Yeop X. Oh ◽  
Je Young Park
Keyword(s):  
Molecular Weight ◽  
Lactic Acid ◽  
Organic Acids ◽  
Organic Acid ◽  
High Molecular Weight ◽  
Acid Catalyst ◽  
Gel Permeation Chromatography ◽  
Controlled Environment ◽  
Direct Polycondensation ◽  
Melt Polycondensation

In this study, high molecular weight (HMW) poly (l-lactic acid)s (PLLAs) were synthesized by direct polycondensation using organic acid catalysts alone in a nitrogen-controlled environment. The melting point and enthalpy of the pre-polymer produced by melt polycondensation increased as molecular weight grew during solid-state polycondensation. It was observed that the nitrogen-controlled external environment had lower molecular weight than air, but the low molecular weight tail was significantly reduced, as indicated by gel permeation chromatography. This is because it inhibited the reverse reaction by preventing the penetration of water inside the reactor. Also, the control of moisture improved the color of PLLA. The amount of organic acid catalyst used was 1 wt%, which was favorable for achieving HMW. Both p-toluenesulfonic acid and 4-ethylbenzenesulfonic acid are examples of organic acids that were able to produce HMW PLLA.

scholarly journals 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 ◽  
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.

Stereocomplex electrospun fibers from high molecular weight of poly(L-lactic acid) and poly(D-lactic acid)

2020 ◽  
Vol 40 (2) ◽  
pp. 136-142 ◽  
Author(s):  
Homa Maleki ◽  
Hossein Barani
Keyword(s):  
Molecular Weight ◽  
Lactic Acid ◽  
Thermal Properties ◽  
High Molecular Weight ◽  
Chemical Properties ◽  
Electrospun Fibers ◽  
Scanning Calorimetry ◽  
Force Microscopy ◽  
Atomic Force ◽  
Electrospinning Method

AbstractThe stereocomplex formation is a promising method to improve the properties of poly(lactide) (PLA)-based products due to the strong interaction of the side-by-side arrangement of the molecular chains. Recently, electrospinning method has been applied to prepare PLA stereocomplex, which is more convenient. The objective of the current study is to make stereocomplexed PLA nanofibers using electrospinning method and compare their properties and structures with pure poly(l-lactide) (PLLA) fibers. The stereocomplexed fibers were electrospun from a blend solution of high molecular weight PLLA and poly(d-lactide) (1:1 ratio). The morphology of the obtained electrospun fibers was examined by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Differential scanning calorimetry was applied to study their thermal properties and crystallinity. Fourier transform infrared spectroscopy (FTIR) test was conducted on the samples to characterize their chemical properties. The SEM and AFM images indicated that smooth uniform fibers with a cylindrical structure were produced. Besides, the FTIR results and thermal properties confirmed that only stereocomplex crystallites formed in the resulting fibers via the electrospinning method.

scholarly journals Biosynthesis of glycoproteins by membranes of Acer pseudoplatanus. Incorporation of mannose and N-acetylglucosamine

1980 ◽  
Vol 192 (2) ◽  
pp. 569-577 ◽  
Author(s):  
J Barr ◽  
P Nordin
Keyword(s):  
Molecular Weight ◽  
Amino Acid ◽  
High Molecular Weight ◽  
Gel Permeation Chromatography ◽  
Monosaccharide Composition ◽  
Paper Electrophoresis ◽  
Acer Pseudoplatanus ◽  
Gel Permeation ◽  
Chloroform Methanol ◽  
Insoluble Pellet

Membrane preparations from Acer pseudoplatanus suspension cultures were demonstrated to incorporate radioactivity from GDP-[U-14C]mannose and UDP-N-acetyl-[6-(3)H]glucosamine into high-molecular-weight polymers characterized as glycoprotein. From 20 to 25% of the 14C was incorporated as fucose with the remainder as mannose, whereas 90% of the 3H was incorporated as N-acetylglucosamine with the remainder as N-acetylgalactosamine. Pronase digestion yielded radioactive glycopeptides that were separated into four fractions by gel-permeation chromatography and paper electrophoresis. The isolated glycopeptides differed in molecular weight and isotopes incorporated, as well as in amino-acid and monosaccharide composition. The membrane preparation also incorporated radioactivity from the added nucleotides into chloroform/methanol (2:1, v/v)- and chloroform/methanol/water (10:10:3, by vol.)-soluble lipids, and into an insoluble pellet.

Gel permeation chromatography of high molecular weight cellulose trinitrate

Polymer ◽  
1978 ◽  
Vol 19 (12) ◽  
pp. 1421-1426 ◽  
Author(s):  
C. Holt ◽  
W. Mackie ◽  
D.B. Sellen
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Gel Permeation Chromatography ◽  
Gel Permeation

Synthesis of Poly(D,L-Lactic Acid-Co-Glucose) via Direct Polycondensation and its Characterization

2011 ◽  
Vol 80-81 ◽  
pp. 370-374 ◽  
Author(s):  
Shi He Luo ◽  
Zhao Yang Wang ◽  
Dong Na Huang ◽  
Chao Xu Mao ◽  
Jin Feng Xiong
Keyword(s):  
Drug Delivery ◽  
Lactic Acid ◽  
Polylactic Acid ◽  
1H Nmr ◽  
Biodegradable Material ◽  
Direct Polycondensation ◽  
Carrier Material ◽  
Melt Polymerization ◽  
Drug Delivery Carrier ◽  
Melt Polycondensation

Directly using cheap D,L-lactic acid (D,L-LA) and glucose (Glu) as starting materials, biodegradable material poly(D,L-lactic acid-co-Glucose) [P(D,L-LA-co-Glu)] was synthesized via melt polycondensation. When n(Glu) : n(D,L-LA) = 1:200, the appropriate synthetic condition is that: after 120 °C prepolymerization for 5 h, 160 °C melt polymerization catalyzed by w(SnCl2) = 0.5% for 5 h. P(D,L-LA-co-Glu) with different molar feed ratios were synthesized and characterized with [η], FTIR, 1H NMR, GPC and XRD. The Tg of all copolymer P(D,L-LA-co-Glu) was lower than that of homopolymer polylactic acid directly synthesized via melt polycondensation. The copolymers with Mw from 2,100 Da to 5,100 Da could meet the demand of drug delivery carrier material.

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