Gelation Crystallization of Poly(L-Lactide) in Solvents of Varying Molecular Size

2007 ◽  
Vol 15 (5) ◽  
pp. 389-393
Author(s):  
Hong Hao ◽  
Guozheng Liang ◽  
Junmin Zhao
Keyword(s):  
Differential Scanning Calorimetry ◽  
Ethylene Glycol ◽  
Crystallization Rate ◽  
Molecular Size ◽  
Large Molecule ◽  
X Ray Diffraction ◽  
Poly Ethylene Glycol ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Poly Ethylene

The crystallization behaviour of poly(L-lactide) (PLLA) samples prepared in large-molecule solvents, such as poly(ethylene glycol) (PEG), was studied by differential scanning calorimetry (DSC) and X-ray diffraction. The results indicate that those samples recovered from large-molecule solvents exhibit higher crystallinity, non-isothermal crystallization temperature and faster crystallization rate than the ones crystallized in a small-molecule solvent. The crystallinity of samples from PLLA/PEG gel is about 73% measured by the DSC. The molar size of the solvent has a large influence on the formation of helical conformations and, thereby on the crystallization rate of PLLA in solution.

Plasticizer effect on melt blending of polylactide stereocomplex

e-Polymers ◽  
2017 ◽  
Vol 17 (5) ◽  
pp. 409-416 ◽  
Author(s):  
Yottha Srithep ◽  
Dutchanee Pholharn
Keyword(s):  
Thermal Stability ◽  
Differential Scanning Calorimetry ◽  
Crystallization Rate ◽  
Wide Angle ◽  
Melt Blending ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Neat Plla ◽  
Internal Mixer

AbstractPoly(l-lactide) (PLLA)/poly(d-lactide) (50/50) with plasticizer contents ranging from 2% to 16% w/w were prepared by melt blending using an internal mixer. Wide-angle X-ray diffraction, Fourier transform infrared spectroscopy and differential scanning calorimetry results confirmed that complete stereocomplex polylactide crystallites without any homocrystallites were produced. Compared to neat PLLA, the melting temperature of the stereocomplex polylactide and its plasticized samples was approximately 55°C higher. Higher plasticizer contents decreased glass transition temperature of the stereocomplex, which implied higher flexibility and enhanced the crystallization rate. However, the plasticizer in the stereocomplex reduced the thermal stability.

Thermo-Responsive Supramolecular Hybrid Hydrogels Formed by Graphene Oxide-Grafted-Poly(Ethylene Glycol) and α-Cyclodextrin

2013 ◽  
Vol 718-720 ◽  
pp. 172-175
Author(s):  
Song Hua Kong ◽  
Mi Zhou ◽  
Xiao Feng Ye ◽  
Xin Qian
Keyword(s):  
Graphene Oxide ◽  
Ethylene Glycol ◽  
Coupling Reaction ◽  
X Ray Diffraction ◽  
Poly Ethylene Glycol ◽  
Hydrogen Bond Interaction ◽  
X Ray ◽  
Hybrid Hydrogels ◽  
Poly Ethylene ◽  
Glycol Methyl Ether

Poly(ethylene glycol) methyl ether-grafted-graphene oxide (GO) was synthesized by a coupling reaction and formed inclusion complexes (ICs) after selective threading of the mPEG segments of the GO-mPEG through the cavities of α-cyclodextrins (α-CDs) units. The polypseudorotaxane structures of the as-obtained hydrogels were confirmed by X-ray diffraction, TGA, DSC, and SEM. The complexation of the mPEG segments with α-CDs and the hydrogen-bond interaction between CDs resulted in the formation of supramolecular hybrid hydrogels with a strong network. The resultant hybrid hydrogels were found to be thermo-responsive, and could be applied as a promising drug delivery system.

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