Stereocomplex formation between poly(L-lactic acid) and poly(D-lactic acid) with disproportionately low and high molecular weights from the melt

2011 ◽  
Vol 61 (3) ◽  
pp. 442-450 ◽  
Author(s):  
Hideto Tsuji ◽  
Leevameng Bouapao
Keyword(s):  
Lactic Acid ◽  
Molecular Weights ◽  
Stereocomplex Formation

Click chemistry synthesis, stereocomplex formation, and enhanced thermal properties of well-defined poly(l-lactic acid)-b-poly(d-lactic acid) stereo diblock copolymers

2017 ◽  
Vol 8 (6) ◽  
pp. 1006-1016 ◽  
Author(s):  
Lili Han ◽  
Qing Xie ◽  
Jianna Bao ◽  
Guorong Shan ◽  
Yongzhong Bao ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Thermal Properties ◽  
Thermal Resistance ◽  
Click Chemistry ◽  
Diblock Copolymers ◽  
Molecular Weights ◽  
Stereocomplex Formation

PLLA-b-PDLAs with well-controlled molecular weights, compositions, highly enhanced stereocomplexation ability, and thermal resistance were synthesized by ROP and click chemistry.

scholarly journals Evaluation of the Efficiency of Ethanol Precipitation and Ultrafiltration on the Purification and Characteristics of Exopolysaccharides Produced by Three Lactic Acid Bacteria

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Manel Ziadi ◽  
Taroub Bouzaiene ◽  
Sana M’Hir ◽  
Kaouther Zaafouri ◽  
Ferid Mokhtar ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Lactobacillus Plantarum ◽  
Lactococcus Lactis ◽  
Leuconostoc Mesenteroides ◽  
Ftir Analysis ◽  
Molecular Weights ◽  
Molar Ratios ◽  
Monomer Composition ◽  
Ethanol Precipitation

Exopolysaccharides (EPS) produced by three Lactic Acid Bacteria strains,Lactococcus lactisSLT10,Lactobacillus plantarumC7, andLeuconostoc mesenteroidesB3, were isolated using two methods: ethanol precipitation (EPS-ETOH) and ultrafiltration (EPS-UF) through a 10 KDa cut-off membrane. EPS recovery by ultrafiltration was higher than ethanol precipitation forLactococcus lactisSLT10 andLactobacillus plantarumC7. However, it was similar with both methods forLeuconostoc mesenteroidesB3. The monomer composition of the EPS fractions revealed differences in structures and molar ratios between the two studied methods. EPS isolated fromLactococcus lactisSLT10 are composed of glucose and mannose for EPS-ETOH against glucose, mannose, and rhamnose for EPS-UF. EPS extracted fromLactobacillus plantarumC7 andLeuconostoc mesenteroidesB3 showed similar composition (glucose and mannose) but different molar ratios. The molecular weights of the different EPS fractions ranged from 11.6±1.83 to 62.4±2.94 kDa. Molecular weights of EPS-ETOH fractions were higher than those of EPS-UF fractions. Fourier transform infrared (FTIR) analysis revealed a similarity in the distribution of the functional groups (O-H, C-H, C=O, -COO, and C-O-C) between the EPS isolated from the three strains.

Biodegradable hydrogels based on stereocomplex formation between lactic acid oligomers grafted to dextran

2001 ◽  
Vol 72 (1-3) ◽  
pp. 47-56 ◽  
Author(s):  
S.J de Jong ◽  
S.C De Smedt ◽  
J Demeester ◽  
C.F van Nostrum ◽  
J.J Kettenes-van den Bosch ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Biodegradable Hydrogels ◽  
Stereocomplex Formation

Monodisperse Enantiomeric Lactic Acid Oligomers:  Preparation, Characterization, and Stereocomplex Formation

1998 ◽  
Vol 31 (19) ◽  
pp. 6397-6402 ◽  
Author(s):  
S. J. de Jong ◽  
W. N. E. van Dijk-Wolthuis ◽  
J. J. Kettenes-van den Bosch ◽  
P. J. W. Schuyl ◽  
W. E. Hennink
Keyword(s):  
Lactic Acid ◽  
Stereocomplex Formation

Synthesis and Characterization of Poly (L-Lactic acid) Containing the Azobenzene Mesogens

2011 ◽  
Vol 181-182 ◽  
pp. 185-188
Author(s):  
Run Tao Dong ◽  
Qing Bin Xue ◽  
Ling Min Sun ◽  
Quan Xuan Zhang
Keyword(s):  
Lactic Acid ◽  
Optical Rotation ◽  
Gel Permeation Chromatography ◽  
Helical Structure ◽  
Feed Ratio ◽  
Scanning Calorimetry ◽  
Molecular Weights ◽  
H Nmr ◽  
Azobenzene Mesogens

A series of azobenzene containing group Poly (L-lactic acid) (PLLA) were synthesized by Ring-Opening Polymerization of L-lactide (L-LA) catalysted by Sn (Oct)2initiated by alcohol-OH containing the azobenzene chromophores. Their molecular weights were well controlled by the feed ratio as characterized by Gel Permeation Chromatography (GPC) and1H NMR Spectrometry and agreed well with theoretical values. The thermal properties and liquid crystal phases were investigated by Differential Scanning Calorimetry (DSC), polarized optical microscopy (POM) and X-ray Diffraction (XRS) measurements. Cis-trans photoisomerization behavior of the polymers in the solutions and the films were studied with UV irradiation. By the Circular Dichroism Spectroscopy (CD) characterization of the solutions and films of the polymer, the PLLA segments show huge optical rotation power in helical structure.

Plasticizing effect of poly(ethylene glycol)s with different molecular weights in poly(lactic acid)/starch blends

2015 ◽  
Vol 132 (16) ◽  
pp. n/a-n/a ◽  
Author(s):  
Yunan Yu ◽  
Yan Cheng ◽  
Jiawei Ren ◽  
Erping Cao ◽  
Xiaowei Fu ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Ethylene Glycol ◽  
Poly Lactic Acid ◽  
Poly Ethylene Glycol ◽  
Molecular Weights ◽  
Starch Blends ◽  
Poly Ethylene

scholarly journals New Poly(Hydroxylauric-co-Lactic Acid) Liquid Polymer for Dissolving Lipophilic Drugs

KIMIKA ◽  
2017 ◽  
Vol 28 (1) ◽  
pp. 20-25
Author(s):  
Florentino C. Sumera ◽  
Shienna Marie A. Pontillas ◽  
Josanelle Angela V. Bilo ◽  
John Marty Mateo
Keyword(s):  
Lactic Acid ◽  
1H Nmr Spectroscopy ◽  
Controlled Drug Delivery ◽  
Gel Permeation Chromatography ◽  
Metal Catalyst ◽  
Pharmaceutical Companies ◽  
Molecular Weights ◽  
Liquid Polymer ◽  
Gel Permeation ◽  
Ft Ir

A liquid, biocompatible polyester based polymer, which could facilitate injectable formulations by simple mixing with the active substance (drug) is much needed by the pharmaceutical companies. A favourite candidate is polylactic acid (PLA) which is biocompatible and biodegradable. However PLA is solid with high crystallinity. Thus, in this research, hydroxylauric acid (HOLA) was copolymerized with lactic acid (LA) in different ratios by polycondensation technique at 180 °C, without a metal catalyst and avoiding the formation of interfering lactides, to provide a liquid polyester. The copolymers molecular weights were determined by Gel Permeation Chromatography (GPC) and their physical states indicated as solid or liquid were noted. The structures as polyesters were confirmed by FT-IR and 1H NMR spectroscopy. Poly(HOLA:LA)  products from reactant ratios 0:100 is solid, while ratios of 20:80, 40:60 are mixed (paste) and 60:40, 80:20 and 100:0 are liquids. Thus, the liquid polyesters from the polycondensation of HOLA and LA without catalyst  were picked as potential candidates for dissolving hydrophobic drugs that could be used as injectables in controlled drug delivery experiments.

Sign in / Sign up

Export Citation Format

Share Document