INVESTIGADORES
KOLENDER Adriana Andrea
congresos y reuniones científicas
Título:
Synthesis of stereoregular poly-O-methyl-[m,n]-polyurethanes derived from D-mannitol
Autor/es:
KOLENDER, ADRIANA A.; FIDALGO, DANIELA M.; VARELA, OSCAR
Lugar:
Madrid
Reunión:
Simposio; 26th International Carbohydrate Symposium; 2012
Institución organizadora:
International Carbohydrate Organization
Resumen:
The design of new polymers with enhanced hydrophilicity and biodegradability starting from carbohydrate-derived monomers has attracted considerable attention. Carbohydrates are massive renewable resources able to provide monomers suitable for the synthesis of polycondensates. The inclusion of hydrophilic monomers into the polymer chain facilitates water attack, increasing the hydrolytic degradation of the material. Polyurethanes are useful materials with wide industrial and biomedical applications. To increase the biodegradability of these polymers, selectively protected derivatives of carbohydrates have been employed as starting materials. Thus, linear [m,n]-polyurethanes were synthesized by reaction of diisocianates with benzyl derivatives of alditols.1 In addition, to avoid the use of toxic diisocyanates, the polycondensation of alkyl diamines with 1,6-bis-O-phenoxycarbonyl derivatives of galactitol (meso form) was employed to afford polyurethanes with pendant hydroxy groups.2 Recently, we have developed a polymerization method to yield [n]-polyurethanes, in the absence of metal catalysts, which involves -amino--phenylcarbonate derivatives of alkanes or alditols as monomers.3 We report here the polycondensation of 2,3,4,5-tetra-O-methyl-1,6-di-O-phenyloxycarbonyl-D-mannitol (2) with several ,-diamines (3, 5-7) of different chain lengths, including the per-O-methyl derivative of 1,6-diamino-1,6-dideoxy-D-mannitol (3). The reaction afforded successfully the linear and stereoregular [m,n]-polyurethanes 4, 8-10. In particular, the stereoregularity of polymer 4 relies on the C2 symmetry of the chiral sugar-based comonomers 2 and 3. The reaction conditions for the polymerization were optimized, in order to improve the yields and increase the molecular weights of the isolated polymers. The [m,n]-polyurethanes obtained posses constitutionally uniform structures, free of urea linkages. The molecular weights were estimated by NMR spectroscopy and GPC (Mn 10400-17500). Themogravimetric analysis of the polymers indicated that decomposition starts above 250 ºC. The thermal behavior was also studied by DSC, which indicated that all of the polyurethanes were amorphous materials with glass transition temperatures (Tg) in the range 39-62 ºC. These thermal transitions were detected during repeated heating and cooling cycles.