Many important biochemical compounds, such as proteins and DNA, are actually polymers composed of amino acids or nucleic acids.  Gelatin is an amino acid peptide polymer with a molecular weight between 30,000 and 100,000.  Its gelling action arises from the hydrogen bonding crosslinking between gelatin strands.  As the crosslinking per unit volume of the material increases, the stiffness increases. If a series of gelatin solutions is prepared, the Young's Modulus for each solution can be measured, and the amount of crosslinking determined from the Young's Modulus. The molecular weight of the gelatin is determined by measuring the viscosity of a series of dilute gelatin solutions.  To facilitate the viscosity measurements for large classes, the viscosity can be corrected for temperature.  A series of normal gelatin solutions is prepared with the gelatin concentrations ranging from 0.5 to 3.0 times that of normal Jell-O.  The Young's Modulus is determined by depression measurements, and crosslinking density calculated.

Gelatin as a polymer for physical chemistry experiments

245th National Meeting (2013)

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