Summary
Turbidity and rheological features during gelation of semidilute solutions of pectin via the Ugi multicomponent condensation reaction have been investigated at different polymer and cross-linker concentrations at ambient temperature. The gelation time of the system decreased with increasing polymer and cross-linker concentrations. At the gel point, a power law frequency dependence of the dynamic storage modulus (G’∼ωn’) and loss modulus (G”∼ωn”) was observed with n’=n”=n. The value of the power law exponent is about 0.6∼0.7 for all the gelling systems, which is close to that predicted (0.7) from the percolation model. The elastic properties of the gels continue to grow over a long time in the post-gel region, and a solidlike response is observed at later stages during the gelation process. The turbidity of the gelling system is higher as the polymer and cross-linker concentrations rise, but the turbidity is virtually unaffected during an extended time after the formation of the incipient gel. It was demonstrated that polymer and cross-linker concentrations could be utilized to tune the physical properties, such as transparency and viscoelasticity, of the Ugi hydrogels.
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Werner, B., Bu, H., Kjøniksen, AL. et al. Characterization of Gelation of Aqueous Pectin via the Ugi Multicomponent Condensation Reaction. Polym. Bull. 56, 579–589 (2006). https://doi.org/10.1007/s00289-006-0522-6
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DOI: https://doi.org/10.1007/s00289-006-0522-6