posted on 2024-02-19, 07:04authored byHikaru Higuchi, Tomoko Ikeda-Fukazawa
To
investigate the mechanisms of interactions between a hydrophobic
polymer and water, molecular dynamics calculations and Raman spectroscopic
measurements of cis-1,4-polyisoprene (PI)-water systems
were performed. The results show that PI in water undergoes a coil–globule
transition at around 248 K. The transition is attributed to changes
in the density and diffusivity of water. The volume expansion of the
supercooled liquid water induces the coil structure of PI. The phase
separation of PI from water with an increase in the self-diffusion
coefficient of water molecules results in the globule structure of
PI. The self-diffusion coefficient of free water with PI is larger
than that of pure water because PI has an effect to decrease the hydrogen-bonding
strength of water. The result suggests that the effects of the coexisting
water are important factors governing the physical and chemical properties
of hydrophobic polymers.