Linked Life Data

18835487

Source:http://linkedlifedata.com/resource/pubmed/id/18835487

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
2008-10-22
pubmed:abstractText
Cononsolvency-induced micellization kinetics of a pyrene end-labeled diblock copolymer of N-isopropylacrylamide and oligo(ethylene glycol) methyl ether methacrylate, Py-PNIPAM-b-POEGMA, was investigated in detail via a combination of stopped-flow light-scattering and fluorescence techniques. Upon a stopped-flow jump from pure methanol to proper methanol/water mixtures, scattered light intensity exhibited an initial increase and then stabilized out; whereas the time-dependence of monomer to excimer fluorescence intensity ratios (I E/I M) revealed an abrupt increase followed by a gradual decrease to plateau values. The dynamic traces of scattered intensity can be well fitted by double exponential functions, the obtained tau 1, scat and tau 2, scat can be ascribed to processes of forming quasi-equilibrium micelles and their relaxation into final equilibrium states, respectively. On the other hand, a triple exponential function was needed to fit the dynamic traces of I E/I M, leading to three characteristic relaxation times (tau 1, fluo, tau 2, fluo, and tau 3, fluo). It was found that the time scales of tau 1, scat and tau 2, scat obtained from stopped-flow light scattering were in general agreement with tau 2, fluo and tau 3, fluo obtained from stopped-flow fluorescence. Considering that excimer fluorescence is extremely sensitive to small aggregates, the newly detected fast process (tau 1, fluo) approximately 10 ms) by stopped-flow fluorescence should be ascribed to the early stage of micellization, i.e., the burst formation of small transient micelles, in which light scattering detection was still not sensitive enough. These small transient micelles fused and grew into quasi-equilibrium micelles, which then slowly relaxed into the final equilibrium state.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
1095-7103
pubmed:author
pubmed:issnType
Electronic
pubmed:day
1
pubmed:volume
328
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
196-202
pubmed:dateRevised
2009-11-11
pubmed:meshHeading
pubmed:year
2008
pubmed:articleTitle
Cononsolvency-induced micellization kinetics of pyrene end-labeled diblock copolymer of N-isopropylacrylamide and oligo(ethylene glycol) methyl ether methacrylate studied by stopped-flow light-scattering and fluorescence.
pubmed:affiliation
Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui, China.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, Non-U.S. Gov't