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Luigi Gentile, Giuseppina De Luca, Filipe E. Antunes, Cesare Oliviero Rossi, Giuseppe Antonio Ranieri
Thermogelation Analysis Of F127-Water Mixtures By Physical Chemistry Techniques
Appl. Rheol. 20:5 (2010) 52081 (9 pages)
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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)
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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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