Linked Life Data

17243742

Source:http://linkedlifedata.com/resource/pubmed/id/17243742

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
5
pubmed:dateCreated
2007-2-20
pubmed:abstractText
Ring-opening polymerization of D,L-lactide was carried out in the presence of monohydroxylated poly(ethylene glycol) (PEG) with Mn of 2000 and 5000, using zinc powder as catalyst. The resulting PEG-b-polylactide (PEG-PLA) diblocks with various ethylene oxide/lactyl (EO/LA) ratios were coupled with adipoyl chloride to yield PEG-PLA-PEG triblock copolymers. N-Dimethylaminopyridine (DMAP) was used as catalyst. The obtained PEG-PLA-PEG triblock copolymers were characterized by various analytical techniques such as IR, 1H NMR, size exclusion chromatography, X-ray diffraction, and differential scanning calorimetry. Data showed that all the copolymers were semicrystalline with the PEG-type crystalline structure, the crystallinity decreasing with increasing PLA block length. Bioresorbable hydrogels were prepared from the water-soluble triblock copolymers. Rheological measurements showed a gel-sol transition with increasing temperature and gelation was found to be thermoreversible. The copolymer solution behaves like a viscoelastic liquid above the gel point and like a viscoelastic solid below the gel point. The critical gelation concentration, the gel-sol transition temperature at a given concentration, and corresponding moduli depend on both the EO/LA ratio and the molecular weight of the copolymers. It is assumed that gelation results from interactions between PEG blocks at low temperatures and that these interactions are disrupted as the temperature is elevated. The shrinking of PEG blocks with increasing temperature seems to be in agreement with the variation of the gel-sol transition temperatures.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0743-7463
pubmed:author
pubmed:issnType
Print
pubmed:day
27
pubmed:volume
23
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
2778-83
pubmed:meshHeading
pubmed:year
2007
pubmed:articleTitle
Synthesis and gelation properties of PEG-PLA-PEG triblock copolymers obtained by coupling monohydroxylated PEG-PLA with adipoyl chloride.
pubmed:affiliation
Centre de Recherche sur les biopolymères Artificiels, Faculté de Pharmachie, University Montpellier I, 34060 Montpellier, France.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't