Synthesis and Thermal Responses of Polygonal Poly(ethylene glycol) Analogues |
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| Authors: | Shunichi Kawasaki Dr. Takahiro Muraoka Prof. Tsutomu Hamada Kazuki Shigyou Prof. Fumi Nagatsugi Prof. Kazushi Kinbara |
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| Affiliation: | 1. Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Midori-ku, Yokohama, Japan;2. Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Aoba-ku, Sendai, Japan;3. Precursory Research for Embryonic Science and Technology, Japan Science and Technology Agency, Kawaguchi, Saitama, Japan;4. School of Materials Science, Japan Advanced Institute of Science and Technology, Nomi, Ishikawa, Japan;5. (+81)?45‐924‐5836 |
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| Abstract: | As a new type of topological poly(ethylene glycol) (PEG) analogue, a series of polygonal PEGs with digonal to hexagonal structures were developed. Polygonal PEGs with structures between the digonal and tetragonal types showed molecular‐level dispersion in water at 20 °C, whereas the pentagonal and hexagonal PEGs aggregated, which is suggestive of enhanced hydrophobicity by ring expansion. Heating induced conformational changes in the polygonal PEGs and increased their hydrophobicity. Among the polygonal PEGs, only the trigonal and hexagonal PEGs showed a distinct thermal response to form and increase the size of the aggregates, respectively. Given that tetragonal and pentagonal PEGs only marginally responded to heat treatment, the thermal responses are likely due to a topological effect. At low temperatures, the larger polygonal PEGs are more restricted despite the expanded rings. The trigonal PEG showed the largest change in mobility, whereas the tetragonal PEG exhibited the smallest change. Hence, the topology of the polygonal PEGs influences the intramolecular packing and the local dynamics. |
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| Keywords: | aggregation conformational changes macrocycles poly(ethylene glycol) topology |
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