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PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
31
pubmed:dateCreated
2009-9-1
pubmed:abstractText
Low-molecular-weight cationic surfactants, dodecyltrimethylammonium bromide (DTAB) and cetyltrimethylammonium bromide (CTAB), were introduced to dilute aqueous solutions of thermosensitive poly(ethylene oxide)-b-poly(N-isopropylacrylamide) (PEO-b-PNIPAM) block copolymers at concentrations (C(s)) either lower or higher than the critical micelle concentrations (cmc) of the surfactants. The copolymer/surfactant mixtures were investigated by dynamic and static light scattering at different temperatures. At temperature lower than the aggregation temperature (T(agg)), the disaggregation of the copolymers from the loose associations was observed upon addition of the surfactants(.) The thermo-induced aggregation behavior was found to be profoundly influenced with the cooperation of cationic surfactants in terms of T(agg) and the structural characteristics of the aggregates formed at high temperature. In general, T(agg) was increased together with the decrease in the size and molecular weight of the aggregates. These were attributed to the copolymer/surfactant interactions and the electrostatic repulsion coming from the ionic head groups of the surfactants within the mixed aggregates. These changes were much more pronounced at higher C(s). CTAB, which has a longer hydrophobic tail, displayed higher influences compared to DTAB. The formation of vesicles, by one of the copolymers, was suppressed in the presence of CTAB. At the higher CTAB concentration, only small mixed aggregates with very low mass were observed even at the highest temperature investigated.
pubmed:language
eng
pubmed:journal
pubmed:status
PubMed-not-MEDLINE
pubmed:month
Aug
pubmed:issn
1520-6106
pubmed:author
pubmed:issnType
Print
pubmed:day
6
pubmed:volume
113
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
10600-6
pubmed:year
2009
pubmed:articleTitle
Thermo-induced aggregation behavior of poly(ethylene oxide)-b-poly(N-isopropylacrylamide) block copolymers in the presence of cationic surfactants.
pubmed:affiliation
Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui, China.
pubmed:publicationType
Journal Article