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Gelation of charged bio-nanocompartments induced by associative and non-associa...
Antunes, Filipe E.; Coppola, Luigi; Rossi, Cesare Oliviero; Ranieri, Giuseppe AntonioVesicles composed of sodium oleate (NaO) and monoolein (MO) are adequate candidates for drug nanoencapsulation and controlled release due to their stability and perceived biocompatibility. The object of the present study is to design hydrogels based on those anionic vesicles and polymers of both non-associative and associative type. The selected macromolecules were k-carrageenan (KC), carboxymethyl cellulose (C...
How does a non-ionic hydrophobically modified telechelic polymer interact with ...
Santos, Tiago dos; Medronho, Bruno; Antunes, Filipe E.; Lindman, Björn; Miguel, MariaThe association between hydrophobically modified polyethylene glycol, HM-PEG, and non-ionic vesicles of tetraethylene glycol monododecyl ether, C12E4, was investigated. HM-PEG is in a triblock form, with an alkyl chain attached to each hydrophilic polymer-end. Such polymer structure is denoted as telechelic. The vesicle average radius was measured by self-diffusion measurements. The system exhibits both a monop...
Aggregation and gelation in hydroxypropylmethyl cellulose aqueous solutions
Silva, Sérgio M. C.; Pinto, Fátima V.; Antunes, Filipe E.; Miguel, Maria G.; Sousa, João J. S.; Pais, Alberto A. C. C.http://www.sciencedirect.com/science/article/B6WHR-4TC923M-1/2/012a59092ead1ce270813efcf98c1fb2
Polymer-vesicle association
Antunes, Filipe E.; Marques, Eduardo F.; Miguel, Maria G.; Lindman, BjörnMixed polymer-surfactant systems have been intensively investigated in the last two decades, with the main focus on surfactant micelles as the surfactant aggregate in interaction. The main types of phase behavior, driving forces and structural/rheological effects at stake are now fairly well understood. Polymer-vesicle systems, on the other hand, have received comparatively less attention from a physico-chemica...
Shear rheology and phase behaviour of sodium oleate/water mixtures
Antunes, Filipe E.; Coppola, Luigi; Gaudio, Danilo; Nicotera, Isabella; Oliviero, CesareThe knowledge of structural and dynamical properties in binary sodium oleate (NaO)/water mixtures represents a first step for studying new biocompatible structures. In addition, a deeper understanding of their flow behaviour is crucial to control their mechanical properties. The purpose of this investigation was to revisit the binary NaO/water phase diagram through a combined effort of shear-rheology, NMR-diffu...
Mechanisms behind the Faceting of Catanionic Vesicles by Polycations: Chain Cry...
Antunes, Filipe E.; Brito, Rodrigo O.; Marques, Eduardo F.; Lindman, Björn; Miguel, MariaVesicles composed of an anionic and a cationic surfactant, with a net negative charge, associate strongly with a hydrophobically modified polycation (LM200) and with an unmodified polycation with higher charge density (JR400), forming viscoelastic gel-like structures. Calorimetric results show that in these gels, LM200 induces a rise of the chain melting temperature (Tm) of the vesicles, whereas JR400 has the o...
Mixed Systems of Hydrophobically Modified Polyelectrolytes: Controlling Rheolo...
Antunes, Filipe E.; Lindman, Björn; Miguel, Maria G.Rheology and phase separation were investigated for aqueous mixtures of two oppositely charged hydrophobically modified polyelectrolytes. The typical phase separation, normally seen for oppositely charged polymer mixtures, is dramatically reduced by the presence of hydrophobic modification, and phase separation is only detected close to the point of charge neutralization. While the two polyelectrolytes separate...
Network Formation of Catanionic Vesicles and Oppositely Charged Polyelectrolyte...
Antunes, Filipe E.; Marques, Eduardo F.; Gomes, Ricardo; Thuresson, Krister; Lindman, Björn; Miguel, Maria G.In nonequimolar solutions of a cationic and an anionic surfactant, vesicles bearing a net charge can be spontaneously formed and apparently exist as thermodynamically stable aggregates. These vesicles can associate strongly with polymers in solution by means of hydrophobic and/or electrostatic interactions. In the current work, we have investigated the rheological and microstructural properties of mixtures of c...
A rheological investigation of the association between a non-ionic microemulsio...
Antunes, Filipe E.; Thuresson, Krister; Lindman, Björn; Miguel, Maria G.Hydrophobically modified polymers (HM-P) typically behave as thickeners in a wide range of systems. The thickening effect in an aqueous solution of this kind of polymer depends on intermolecular hydrophobic associations and also on chain entanglements if the polymer concentration is significantly above the overlap concentration. In the present investigation a rather short end-capped polymer has been investigate...
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