Soft, tough, and flexible curdlan hydrogels and organogels fabricated by covalent cross-linking

- Soft, tough, and flexible curdlan hydrogels were prepared by covalent cross-linking using ethylene glycol diglycidyl ether.
- CD hydrogels sustained compression to 90% strain and recovered original shape after compression.
- CD organogels were prepared by subsequent acetylation of CD hydrogels.
- CD organogels were resistant to repeating drying and swelling treatment in chloroform.

Soft, tough and flexible curdlan (CD) hydrogels were fabricated by covalent cross-linking of CD using ethylene glycol diglycidyl ether (EGDGE) as a cross-linker. The mechanical properties of the gels were investigated by uniaxial compression test. CD hydrogels showed non-linear elastic behavior. The elastic modulus of CD hydrogels was 0.004-0.011 kPa. CD hydrogels were highly tough and did not fracture under compression to 90% strain at the maximum. The gels could retain water during compression, and no water was squeezed out from the gel. In addition, CD hydrogel could recover the original shape and elastic modulus after 90% compression, indicating its high flexibility. Subsequently, hydroxyl groups of CD hydrogels were acetylated in acetic anhydride and pyridine system to give hydrophobic property, and novel CD organogels were obtained. CD organogel were swollen in chloroform and resistant to repeated drying and swelling treatment in chloroform.

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