Statistical copolymers of methacrylic acid derivatives with hydrophobic spacers and N,N'-dimethylaminoethylmethacrylate: New associating polyampholytes
Rosario Santos-Rosas1, Angel Licea-Claveríe*1 and Karl-Friedrich Arndt2
1 Centro de Graduados e Investigación, Instituto Tecnológico de Tijuana, A.P.1166, 22000 Tijuana, B.C.; México. Tel/Fax: (++52)-(664)-623-3772. E-mail: aliceac@tectijuana.mx, aliceac19@hotmail.com. Address for international Airmail: PO BOX 431461, San Ysidro, CA 92143, U.S.A.
2 Institut für Physikalische Chemie und Elektrochemie, Technische Universität Dresden, D-01062 Dresden, Germany.
]]> Recibido el 24 de julio del 2006.
Abstract
Two series of statistical copolymers containing N,N'-(dimethylamino)ethylmethacrylate (DMAEM) and comonomers derived from methacrylic acid with three and five methylene-units as spacers, were prepared by free radical-copolymerization followed by selective saponification. These statistical copolymers prepared showed strong self-associative properties as revealed by viscosity, static and dynamic light scattering studies. The aggregates formed in aqueous solution show classical ampholytic behaviour with aggregate expansion both in acid and alkaline conditions and aggregate contraction at intermediate pH-values, near the isoelectric point of the system. The contraction of aggregates is shifted to higher pH-values when the content on hydrophobic acid comonomer is increased. The aggregates formed are stable to sonication above a concentration of 0.9 g/L and merge to larger structures at very high or very low pH-values. A conceptual model is proposed that accounts for the observed association behaviour of the copolymers. The statistical ampholytic copolymers studied are an easy to prepare alternative to block-copolymers for the formation of nano-sized aggregates for different applications.
Keywords: Polyampholytes, macromolecular aggregates, hydrophobic self-association, pH-sensitive copolymers.
Resumen
Se prepararon dos series de copolímeros estadísticos conteniendo N,N'-dimetilaminoetil metacrilato (DMAEM) y comonómeros derivados del ácido metacrílico con tres y cinco metilenos como espaciadores, vía polimerización radicálica seguida de saponificación específica. Los copolímeros estadísticos obtenidos mostraron una fuerte tendencia a la autoasociación demostrada en experimentos de viscosidad y dispersión de luz estática y dinámica. Los agregados formados en solución acuosa mostraron comportamiento polianfolítico clásico, con expansión de agregados tanto en condiciones ácidas como en condiciones alcalinas y contracción de agregados a valores intermedios de pH, cercanos al punto isoeléctrico del sistema. La contracción de agregados se recorre a valores mayores de pH cuando se incrementa el contenido de comonómero hidrofóbico-ácido en el copolímero. Los agregados formados son estables al ultrasonido arriba de una concentración de 0.9 g/L y se agrupan en estructuras aun mayores a valores de pH muy altos o muy bajos. Se propone un modelo conceptual para explicar el comportamiento observado de autoasociación de los copolímeros. Los copolímeros anfolíticos estadísticos estudiados representan una alternativa fácil de preparar en comparación con los copolímeros en bloques para la formación de agregados nanométricos para aplicaciones diversas.
Palabras clave: Polianfolitos, agregados macromoleculares, autoasociación hidrofóbica, copolímeros sensibles al pH.
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Acknowledgements
The financial support of the following agencies is gratefully acknowledged: CONACYT-Mexico (Project Nr. 28022-U) and Volkswagen Foundation-Germany (Project Nr. I/76 065). We appreciate the valuable technical support of I.A. Rivero and R. Somanathan (200 MHz-NMR), A. Zizumbo (DSC), S. Richter (DLS) and C. Meissner (SLS). We thank specially IBMAlmaden Research Center for 400 MHz-NMR measurements.
References
1. Bekturov, E.A.; Bakauova, Z.K. Synthetic water-soluble polymers in solution. Hüthig & Wepf Verlag, Basel-Heidelberg-New York, 1986, p163. [ Links ]
2. Wen, S.; Stevenson, W.T.K. Colloid Polym. Sci. 1993, 271, 38-49. [ Links ]
3. Lowe, A.B.; Billingham, N.C.; Armes, S.P. Macromol. 1998, 51, 5991-5998. [ Links ]
4. Nonaka, T.; Matsumura, S.; Ogata, T.; Kurihara, S. J. Membr. Sci. 2003, 212, 39-53. [ Links ]
5. Corpart, J.M.; Candau, F. Macromol. 1993, 26, 1333-1343. [ Links ]
6. Kathmann, E.E.L.; White, L.A.; McCormick, C.L. Macromol. 1997, 30, 5297-5304. [ Links ]
7. Alfrey, T.Jr.; Fuoss, R.M.; Morawetz, H.M.; Pinner, H. J. Amer. Chem. Soc. 1952, 74, 438-441. [ Links ]
8. Ehrlich, G.; Dotty, P. J. Amer. Chem. Soc. 1954, 76, 3764-3777. [ Links ]
9. Patrickios, C.S.; Hertler, W.R.; Abbott, N.L.; Hatton, T.A. Macromol. 1994, 27, 930-937. [ Links ]
10. Nath, S.; Patrickios, C.S.; Hatton, T.A. Biotechnol. Prog. 1995, 11, 99-103. [ Links ]
11. Goloub, T.; de Keizer, A.; Cohen-Stuart, M.A. Macromol. 1999, 32, 8441-8446. [ Links ]
12. Gohy, J.F.; Creutz, S.; Garcia, M.; Mahltig, B.; Stamm, M.; Jérôme, R. Macromol. 2000, 33, 6378-6387. [ Links ]
13. Bütün, V.; Armes, S.P.; Billingham, N.C. Polymer 2001, 42, 5993-6008. [ Links ]
14. Hadjikallis, G.; Hadjiyannakou, S.C.; Vamvakaki, M.; Patrickios, C.S. Polymer 2002, 43, 7269-7273. [ Links ]
15. Bieringer. R.; Abetz, V.; Müller, A.H.E. Eur. Phys. Jnl. E 2001, 5, 5-12. [ Links ]
16. Shalaby, S.W.; McCormick, C.L.; Buttler, G.B. Water soluble polymers: Synthesis, solution properties and application. Amer. Chem. Soc., ACS Symp Ser 467, Washington DC, 1991. [ Links ]
17. Dubin, P.; Bock, J.; Davis, R.; Schulz, D.N.; Thies, C. Macromolecular complexes in chemistry and biology. Springerverlag, Berlin, 1994. [ Links ]
18. Morishima, Y. Trends Polym. Sci. 1994, 2, 31-36. [ Links ]
19. Yusa, S.; Kamachi, M.; Morishima, Y. Langmuir 1998, 14, 6059-6067. [ Links ]
20. Chang, Y.; McCormick, C.L. Macromol. 1993, 26, 6121-6126. [ Links ]
21. Noda, T.; Hashidzume, A.; Morishima, Y. Macromol. 2000, 55, 3694-3704. [ Links ]
22. Rogel-Hernández, E.; Licea-Claverie, A.; Cornejo-Bravo, J.M.; Arndt, K.F. Desig. Monom. Polym. 2001, 4, 343-356. [ Links ]
23. Creutz, S.; Teyssié, P.; Jérôme, R.; Macromol. 1997, 50, 6-9. [ Links ]
24. Arndt, K.F.; Müller, G. Polymer Charakterisierung. Carl Hanser Verlag, München-Wien, 1996, p182. [ Links ]
25. Arndt, K.F.; Müller, G. Polymer Charakterisierung. Carl Hanser Verlag, München-Wien, 1996, p142. [ Links ]
26. Fuoss, R.M.; Strauss, U.P. J. Polym. Sci. 1948, 5, 246- [ Links ] .
27. Förster, S.; Schmidt, M. Adv. Polym. Sci. 1995, 120, 51-133. [ Links ]
28. Bekturov, E.A.; Kudaibergenov, S.E.; Rafikov, S.R. J. Macromol. Sci., Rev. Macromol. Chem. Phys. 1990, C50, 233303. [ Links ]
29. Lowe, A.B.; McCormick, C.L. Chem. Rev. 2002, 102, 4177-4189. [ Links ]
30. Hadjichristidis, N.; Pispas, S.; Floudas, G.A. Block Copolymers: synthetic strategies, physical properties and applications. Wiley-Interscience, Hoboken, NJ, 2003, p. 204. [ Links ]
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