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The thermosensitive hydrogels are widely used in tissue engineering due to their non-invasive application. Special interest of researchers, due to the specific characteristics of both materials, is aimed at composites of natural origin obtained from chitosan hydrogels combined with collagen. The mechanical properties of the thermosensitive chitosan-fish collagen hydrogels and the sol-gel phase transition parameters were determined by the rotational rheometry measurement techniques. Based on comparison of the obtained storage modulus G' curves, it was found that the addition of collagen negatively affects the mechanical properties of composite scaffolds. The addition of this protein substance decreases their elasticity. Only the smallest concentration (0.25g collagen/1 g chitosan) of collagen improves the mechanical properties of composite hydrogels, from 56 kPa to 61 kPa. Conducted non-isothermal studies allowed to conclude that the addition of collagen causes an increasing temperature of sol-gel phase transition. However, the observed changes are not a monotone function of the biopolymer concentration.

Aqueous solutions that undergo reversible thermosensitive gelation around body temperature were developed based on hydrophobically-modified methyl cellulose (HMMC). The approach involved HMMC as the main component of aqueous compositions to provide a system with fast gelling properties, which has not been accomplished with aqueous solutions of unmodified methyl cellulose (MC). MC was modified with the stearyl group as a hydrophobic modifier by controlling the degree of modification. The gelation rate of aqueous solutions containing identical amounts of HMMC and NaCl increased as the temperature increased. The HMMC solutions gelled at a fixed temperature and concentration range, while the unmodified MC solutions did not show sol-to-gel transition. In addition, HMMC solutions exhibited much faster gelation than MC solutions at given polymer and NaCl concentrations. The HMMC/NaCl solutions exhibited the reversible gel-to-sol transition upon cooling below 25°C. The rate of sol-to-gel transition at body temperature, and the reversible gel-to-sol transition at room temperature, were modulated by adjusting the concentration of HMMC and NaCl, respectively. The HMMC/NaCl compositions provided a simple system for accurate control of the thermogelling temperature and the thermogelation rates.

Cholesterol derivatives containing an azobenzene moiety coupled to C3 of a steroidal moiety showed the reversible sol-gel phase transition in certain organic solvents. Strong ICD spectra appeared in the gel phase, but the ICD disappeared in the sol phase. The sol-gel phase transition which accompanies the drastic ICD spectral change was synchronously induced by light-mediated cis-trans isomerism of the azobenzene moiety.

The controlled colour generation and colour erasing phenomena of alkylammonium polyoxomolybdate complexes were first observed in the trans-(1R,2R)-1,2-bis(undecylcarbonylamino)cyclohexane organogel system using the sol-gel phase transition.

Ethyl carbamylated polyrotaxane (ECPR) and propyl carbamylated polyrotaxane (PCPR) were prepared based on the reactions between ethyl/propyl isocyanate and polyrotaxane (PR) in anhydrous DMSO under an argon atmosphere. By changing the alkyl type and substitution ratio, the PR derivative with good water-solubility was obtained and its solutions showed reversible sol–gel phase transition. During the heating process, transition temperature from sol to gel decreased from 32 °C to 18 °C with increasing the solution concentration from 2.44% to 13.5%, while in the cooling process, all the gels with various concentration did not turn into sols until the temperature decreased to 1 °C, exhibiting large hysteresis between heating and cooling.