867 Full Paper Macromolecular Chemistry and Physics wileyonlinelibrary.com DOI: 10.1002/macp.201400029 Melting of Gelatin Gels Containing Laponite, Montmorillonite, and Chitosan Particles J. Rachel Prado, Sergey Vyazovkin* This research examines the effect of the addition of laponite, montmorillonite, and chitosan particles on the melting of gelatin gels. The effect is probed by combining calorimetric meas- urements with isoconversional kinetic analysis. It is found that the addition of the particles tends to increase the heat of melting and decrease the melting temperature. Although the addition of the particles results in a raising of the energy bar- rier to melting, the pre-exponential factors increase as well, causing acceleration of the melting process and decreasing the thermal stability of the gels. The observed effects are explained in terms of the gel structure. J. R. Prado, S. Vyazovkin Department of Chemistry University of Alabama at Birmingham 901 S. 14 th Street, Birmingham, AL 35294, USA E-mail: vyazovkin@uab.edu montmorillonite clay. [18–26] Introduction of solid particles into gelatin is thought to promote additional crosslinks in gelatin through its interaction with the solid surfaces, thus enhancing its mechanical and thermal stability. If interaction between gelatin and solid surfaces affects the gel structure (e.g., the total number crosslinks and the number of crosslinks per individual junction point (knot)), it should be manifested in the process of gel melting. It has been shown [27] that a combination of calorimetric measurements with isoconversional kinetic analysis [28] of gel melting allows one to obtain physical insights into the structure of neat gelatin gels. In the present paper, we extend this approach to explore more complex gelatin gels that include solid particles. 2. Experimental Section Type B gelatin, derived from bovine skin, was purchased from Sigma. According to the manufacturer, this gelatin has the Bloom number 225, the average molecular weight ≈ 50 000 g mol -1 , and the isoelectric point 4.7–5.2. A 40 wt% gelatin gel was cre- ated by heating nanopure water in a water bath at 60 °C then adding powdered gelatin. The sample was stirred and cooled to 1. Introduction Gelatin hydrogels have been used traditionally in food, pharmaceutics, cosmetics, photography, and other indus- tries. Over the past decade, gelatin gels have attracted a great deal of attention as biomedical materials that can be used for tissue engineering and drug delivery. Because gelatin is denatured (unfolded or coiled) form of col- lagen, which is an animal connective tissue protein, it has excellent biocompatibility. It is also inexpensive, bio- degradable, renewable, and environmentally benign. One major disadvantage of gelatin materials is their structural weakness. This problem is addressed by making gelatin- based composite materials that include particulate mate- rials such as hydroxyapatite, [1–9] siloxane, [10–14] layered double hydroxides, [15] silver [16,17] as well as chitosan and Macromol. Chem. Phys. 2014, 215, 867−872 © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim