Grafting of sodium alginate with poly (N-isopropylacrylamide) chains. Study of the thermothickening behavior

• Κύριος συγγραφέας: Ciocoiu, Oana Nicoleta
• Άλλοι συγγραφείς: Στάικος, Γεώργιος
• Μορφή: Thesis
• Γλώσσα: English
• Έκδοση: 2010
• Θέματα: Sodium alginate; Thermothickening; PNIPAM; Αλγινικό οξύ; Μελέτη θερμικής συμπεριφοράς; Πολυ (Ν -ισοπροπυλακρυλαμίδιο); 547.782

Designing new materials with improved or tailored properties is one of the main goals of the chemists. Two common ways are mainly used to get a material with improved or new properties: blending or chemical synthesis. Chemical synthesis is an unlimited method to get new substances with well-defined properties even it is often time consuming and not seldom costly.A rheology study has shown a considerable increase in viscosity of 1% aqueous solutions, 40 and 120 times at 550C, for the graft copolymers with a composition 67 and 80% in PNIPAM respectively as temperature increases above 350C. This behaviour is also related with a critical concentration that has been found around 0.6% for the same copolymers. Fluorescence measurements have shown that this behavior is related with the hydrophobic character and aggregation of PNIPAM chains by increasing temperature over 350C. A dynamic light scattering study in dilute aqueous solutions by varying temperature could provide more information on the kind of the transition taking place and the nature of the particles formed as temperature increases.