Hard-to-soft transition of transparent shape memory gels and the first observation of their critical temperature studied with scanning microscopic light scattering

• Novel transparent shape memory gels (SMGs) are prepared by the bulk polymerization technique.
• It can memorize an original shape that has occurred during the gelation process.
• SMGs are transparent both at room and high temperatures, elastic and thermoresponsive.
• This is the first observation of SMGs by dynamic light scattering.
• The SMGs are showing a critical slowing down around the critical temperature.

The novel transparent shape memory gels (SMGs) have been developed by simple bulk polymerization technique, while the previous SMGs are opaque and whitish ones. It has the ability to memorize an original shape that occurs during the gelation process. It is found that the SMGs are transparent both at room and at high temperature, mechanically elastic as well as thermoresponsive despite the high water contents. By virtue of the transparency of the SMGs, we observe the mesh size of the internal network structure in nanometer scales and the phase transition of the SMGs by dynamic light scattering. This is the first observation of SMGs by light scattering as far as we know. The SMGs show a critical slowing down around the critical temperature where they change the state of phase.

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