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Pivot Concepts:
Gene/Protein
Disease
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Drug
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Target Concepts:
Gene/Protein
Disease
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Query: EC:2.3.1.177 (
BIS
)
957
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
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 theta-temperature of pure PNIPAM due to the association of methyl groups at the periphery of
PEO
shells.
...
PMID:Particle formation and aggregation-collapse behavior of poly(N-isopropylacrylamide) and poly(ethylene glycol) block copolymers in the presence of cross-linking agent. 1538 64
