caa a22 4500 463192486 CHVBK 20180406164913.0 cr unu---uuuuu 170326e20070101xx s 000 0 eng 10.1007/s10973-006-7834-5 doi (NATIONALLICENCE)springer-10.1007/s10973-006-7834-5 Calorimetricapproach to tetronic/water interactions [Elektronische Daten] [Marta Fernandez-Tarrio, Carmen Alvarez-Lorenzo, A. Concheiro] Tetronic® comprises X-shaped copolymers formed by four poly(propylene oxide) (PPO) and poly(ethylene oxide) (PEO) block chains bonded to an ethylene diamine central group. Micellization behaviour of three representative Tetronics (T304, T904 and T1307) was characterized to gain an insight into the interactions between the copolymer unimers and the state of water in their solutions. The enthalpy of demicellization, recorded at 37°C in an isoperibol microcalorimeter, indicated that the process was in all cases exothermic and the enthalpy ranked in the order T1307≥T904>>T304. Micellization is entropy-driven owing to hydrophobic interactions between the PPO chains. DSC analysis showed that the crystallization and melting peaks of the free water remaining in T304 and T904 solutions were progressively shifted toward lower temperatures as the surfactant proportion increased, owing to a colligative effect. Bound water corresponded to 3 water molecules per EO repeating unit. In the case of T1307, which has longer PEO chains, a splitting of the melting peak was observed, one peak appearing around 0°C due to free water and another at -15°C due to interfacial water. As T1307 proportion raised, the enthalpy of the former decreased, whilst the enthalpy of the latter increased. In 40% T1307 solutions, interfacial water overcame the proportion of free water; there being 1 interfacial and 3 bound water molecules per EO repeating unit. Gaussian deconvolution of FTIR spectra also enabled to characterize the evolution of free water as a function of Tetronic proportion. The dependence of micellization and water interaction behaviour on Tetronics structure should be taken into account to use these copolymers as drug solubilizers and micellar carriers. Springer-Verlag, 2007 bound water nationallicence DSC nationallicence free water nationallicence FTIR nationallicence interfacial water nationallicence isoperibol calorimetry nationallicence micellization enthalpy nationallicence poloxamine surfactants nationallicence poly(propylene oxide)-poly(ethylene oxide) block copolymers nationallicence Fernandez-Tarrio Marta Departamento de Farmacia y Tecnología Farmacéutica, Facultad de Farmacia, Universidad de Santiago de Compostela, 15782, Santiago de Compostela, Spain aut Alvarez-Lorenzo Carmen Departamento de Farmacia y Tecnología Farmacéutica, Facultad de Farmacia, Universidad de Santiago de Compostela, 15782, Santiago de Compostela, Spain aut Concheiro A. Departamento de Farmacia y Tecnología Farmacéutica, Facultad de Farmacia, Universidad de Santiago de Compostela, 15782, Santiago de Compostela, Spain aut Journal of Thermal Analysis and Calorimetry Kluwer Academic Publishers 87/1(2007-01-01), 171-178 1388-6150 87:1<171 2007 87 10973 https://doi.org/10.1007/s10973-006-7834-5 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10973-006-7834-5 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Fernandez-Tarrio Marta Departamento de Farmacia y Tecnología Farmacéutica, Facultad de Farmacia, Universidad de Santiago de Compostela, 15782, Santiago de Compostela, Spain aut NATIONALLICENCE 700 1- Alvarez-Lorenzo Carmen Departamento de Farmacia y Tecnología Farmacéutica, Facultad de Farmacia, Universidad de Santiago de Compostela, 15782, Santiago de Compostela, Spain aut NATIONALLICENCE 700 1- Concheiro A. Departamento de Farmacia y Tecnología Farmacéutica, Facultad de Farmacia, Universidad de Santiago de Compostela, 15782, Santiago de Compostela, Spain aut NATIONALLICENCE 773 0- Journal of Thermal Analysis and Calorimetry Kluwer Academic Publishers 87/1(2007-01-01), 171-178 1388-6150 87:1<171 2007 87 10973 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer