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Updated: Jan 26, 2026

Author Spotlight: Unveiling the Structural and Dynamic Aspects of Glycan Molecular Recognition
Published on: May 17, 2024
Solid-State Nuclear Magnetic Resonance (NMR) and Nuclear Magnetic Relaxation Time Analyses of Molecular Mobility and
Masakazu Nishida1, Tomoko Tanaka2, Yoshio Hayakawa3
1National Institute of Advanced Industrial Science and Technology (AIST), Shimoshidami 2266-98, Moriyama-ku, Nagoya 463-8560, Japan. m-nishida@aist.go.jp.
Abstract:
The molecular mobility and compatibility of plasticized polyhydroxyalkanoates (PHA) were investigated, focusing on changes due to copolymerization using either flexible poly (butylene succinate) (PBS) or rigid poly(lactic acid) (PLA) units. For the case of a poly(3-hydroxybutyrate) (PHB) unit in plasticized PHA, copolymerization of either PBS or PLA decreased ¹H and 13C spin-lattice relaxation times in the laboratory frame (T₁H and T₁C) in the same manner, while PBS produced a lower ¹H spin-lattice relaxation time in the rotating frame (T₁ρH) than PLA. Both the signals of ¹H MAS (magic-angle spinning) and 13C PST (pulse saturation transfer) MAS nuclear magnetic resonance (NMR) spectra were sharpened and increased by copolymerization with PBS. A variable temperature relaxation time analysis showed that the decrease of T₁H values was dominated by the ¹H spin diffusion via the interface between PHB and the added polyester because of the good compatibility. Meanwhile, the decrease of T₁C values was dominated by increasingly rapid molecular motions of PHB because of the lowered crystallinity due to the plasticization. Slow molecular motions (kHz order) were enhanced more by the addition of PBS than PLA, although rapid molecular motions (MHz order) were enhanced by either polyester. Several NMR parameters were beneficial for analyzing the manufacturing process as the indexes of polymer compatibility and molecular motions.
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