Abstract
The effect of feed molar ratio of N-isopropylacrylamide (NIPAM) to poly(ethylene oxide) (PEO) on the particle formation of poly(N-isopropylacrylamide) (PNIPAM) and PEO block copolymers (PNIPAM-b-PEO) and their aggregation–collapse behavior have been studied in aqueous solutions. It is found that in the presence of cross-linking agent N,N′-methylenebisacryla-mide (BIS), different morphologies of PNIPAM-b-PEO copolymers can be obtained, including a grafting-like structure, a hemispherical core-shell structure and a well-defined core-shell nanoparticle, as the feed molar amount of NIPAM in the copolymerization is increased. The increase in temperature causes the self-aggregation of grafting-like copolymers and hemispherical particles due to the hydrophobic interaction between locally unshielded PNIPAM blocks prior to the conformational transition of PNIPAM. When the feed molar ratio of NIPAM to PEO exceeds a certain value, a well-defined core-shell nanoparticle can be produced during the copolymerization. At low concentrations, PNIPAM cores of single core-shell nanoparticles can undergo the conformational transition without aggregation. The increase in the concentration of the well-defined core-shell nanoparticles, however, results in a week aggregation at temperatures lower than the Θ-temperature of pure PNIPAM due to the association of methyl groups at the periphery of PEO shells.
Similar content being viewed by others
References
B. Jeong, Y. H. Bae, D. S. Lee and W. Kim, Nature 388 (1997) 860.
T. Miyata, N. Asami and T. Uragami, ibid. 399 (1999) 766.
M. Yamato, O. H. Kwon, M. Hirose, M. Kikuchi and T. Okanok, Biomed. Mater. Res. 55 (2000) 137.
D. Liang, S. Zhiu, L. Song, V. Zaitsev and B. Chu, Macromolecules 32 (1999) 6326.
M. Shibayama and T. Tanaka, Adv. Polym. Sci. 109 (1993) 1.
H. G. Schild, Prog. Polym. Sci. 17 (1992) 163.
E. I. Tiktopulo, V. N. Uversky, V. B. Lushchik, S. I. Klenin, V. E. Bychkova and O. B. Ptitsyn, Macromolecules 28 (1995) 7519.
G. Chen and A. S. Hoffman, Nature 373 (1995) 49.
M. Annaka and T. Tanaka, ibid. 355 (1992) 430.
E. Kokufuta, Y. O. Zhang and T. Tanaka, ibid. 351 (1991) 302.
Z. Hu, X. Zhang and Y. Li, Science 269 (1995) 525.
G. P. Chen, Y. Ito and Y. Imanish, Biotechnol. Bioeng. 53 (1997) 339.
S. Juodkazis, N. Mukai, R. Wakaki, A. Yamaguchi, S. Matsuo and H. Misawa, Nature 408 (2000) 178.
M. D. C. Topp, P. J. Dijkstra, H. Talsma and J. Feijen, Macromolecules 30 (1997) 8518.
P. W. Zhu and D. H. Napper, ibid. 32 (1999) 2068.
R. Pelton, Adv. Colloid Interf. Sci. 85 (2000) 1.
W. F. Polik and W. Burchard, Macromolecules 16 (1983) 978.
M. Polverari and T. G. M. Van Der Ven, J. Phys. Chem. 100 (1996) 13687.
A. Faraone, S. Magazu, G. Maisano, P. Migliardo, E. Tettamanti and V. Villar, J. Chem. Phys. 110 (1999) 1801.
X. Qiu and C. Wu, Macromolecules 30 (1997) 7921.
J. Virtanen and H. Tenhu, ibid. 33 (2000) 5970.
D. H. Napper, in “Polymeric Stabilization of Colloidal Dispersions” (Academic, New York, 1983).
P. W. Zhu and D. H. Napper, Colloids Surf. A113 (1996) 145.
V. A. Baulin and A. Halperin, Macromolecules 35 (2002) 6432.
A. Yekta, B. Xu, J. Duhamel, H. Adiwidjaja and M. A. Winnik, ibid. 28 (1995) 956.
E. Beaudoin, O. Borisov, A. Lapp, L. Billon, R. C. Hiorns and J. Francois, ibid. 35 (2002) 7436.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Zhu, PW. Particle formation and aggregation–collapse behavior of poly(N-isopropylacrylamide) and poly(ethylene glycol) block copolymers in the presence of cross-linking agent. Journal of Materials Science: Materials in Medicine 15, 567–573 (2004). https://doi.org/10.1023/B:JMSM.0000026378.24285.f9
Issue Date:
DOI: https://doi.org/10.1023/B:JMSM.0000026378.24285.f9