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Author index ►Luigi Gentile, Giuseppina De Luca, Filipe E. Antunes, Cesare Oliviero Rossi, Giuseppe Antonio Ranieri
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Thermogelation Analysis Of F127-Water Mixtures By Physical Chemistry Techniques
Appl. Rheol. 20:5 (2010) 52081 (9 pages) ►
Aqueous solutions of F127 pluronic systems exhibit an interesting thermal gelation above a certain concentration. This phenomenon concerns the transition from a liquid-like behavior at low temperatures to a solid-like behavior at high temperatures, and it is due to different temperature responses from the different polymer segments, polypropylene oxide (PPO) and polyethylene oxide (PEO). Such property leads to a structural change in the self assembled macromolecule upon heating, from an isotropic micellar structure to an ordered cubic structure. These two types of assembly are clearly distinct with respect to their rheological behavior.This contribution emphasizes the rheological properties of the pluronic system in micellar and cubic phase, in combination with NMR, Dynamic Light Scattering and DSC information. The results emphasize the gelation process upon heating and a cubic phase characterized by higher storage modulus and higher A and z Weak Gel Model exponents than the micellar phase. Micellar growth upon heating was found within micellar phase. The presented data support the hypothesis that each polymer segment actively participates in the formation of the different phases: while PPO is responsible for micelle formation, PEO plays a dominating role in cubic phase formation. Finally, different stiffness between the core and the corona of the aggregates in the two phases is observed.► Cite this publication as follows:
Gentile L, DeLuca G, Antunes FE, OlivieroRossi C, Ranieri GA: Thermogelation Analysis Of F127-Water Mixtures By Physical Chemistry Techniques, Appl. Rheol. 20 (2010) 52081.
Filipe E. Antunes, Luigi Gentile, Lorena Tavano, Cesare Oliviero Rossi
Rheological characterization of the thermal gelation of poly(N-isopropylacrylamide) and poly(N-isopropylacrylamide)co-Acrylic Acid
Appl. Rheol. 19:4 (2009) 42064 (9 pages) ►
The combined effect of charged addition and molecular weight, Mw, on the thermal gelation and gel dissolution of poly(Nisopropylacrylamide) chains was explored by using Rheological techniques. The synthesized charged derivative is poly(N-isopropylacrylamide co-Acrylic acid). The rheological behavior of the two macromolecules is clearly different: the thermal gelation of the high Mw and charged macromolecule is much more accentuated. This suggests that the gelation at high temperatures only occurs when the inter polymer aggregate distance is sufficiently short to allow polymer bridging; this situation can be achieved by different approaches, such as increasing polymer concentration and increasing polymer persistence length and polymer Mw.► Cite this publication as follows:
Antunes FE, Gentile L, Tavano L, OlivieroRossi C: Rheological characterization of the thermal gelation of poly(N-isopropylacrylamide) and poly(N-isopropylacrylamide)co-Acrylic Acid, Appl. Rheol. 19 (2009) 42064.
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