PMID: 15386964Sep 25, 2004Paper

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
Peng-Wei Zhu

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, result...Continue Reading

Citations

Jul 10, 2019·Langmuir : the ACS Journal of Surfaces and Colloids·Kun YouShicheng Yang

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