Study On The Intercalation And Interaction Of Gelatin-montmorillonite

Gelatin is a kind of protein extracted from animal tissues, which consists of 18kinds of amino acids. There are many kinds of functional groups on the chains ofgelatin, especially —OH, —NH2 and —COOH. Montmorillonite (MMT) is a kind ofnatural layered silicate. The ions and groups of layers and interlayers are also complex,and MMT has many reactive sites. So, many reactions will take place during theintercalation of gelatin-MMT, such as ionic bond, coordination, Van der Waals andhydrophobic interactions. In this paper, the intercalative interaction of —OH,—NH2 and —COOH withMMT were simulated by monofunctional low molecules, such as lauryl alcohol,laurylamine and lauric acid. With the aid of XRD, FTIR and TEM, the interactivestrengths of the three groups with MMT were studied. Meanwhile, polymers that haveonly one functional group were intercalated with MMT to investigate the effect offunctional numbers. The adsorption of gelatin on MMT was investigated underdifferent conditions (such as reactive time, reactive temperature, ultrasonic dispersal,concentration, ionic strength, alcohol and pH). The intercalation effected by thesefactors was also studied. And the thermodynamic process of gelatin-MMTintercalation was analyzed. The optimum intercalative conditions were determined.Finally, the effect of the modification of gelatin or MMT on intercalation wasdiscussed. The results indicated that interaction followed the sequence:—COO－>—NH3 > +—OH >—COOH. That poly(vinyl alcohol) and sodium poly(acrylic acid) did notintercalate into MMT interlayers, suggesting excessive one functional group is notbeneficial for intercalation. The intercalation effected by the factors except fortemperature accorded to that of adsorption. The maximum of gelatin adsorbed wasobtained at isoelectric point (IEP) of gelatin, and interlayer spacing of MMT is thelargest. But gelatin macromolecules could still intercalate into MMT at pH above IEP.The adsorption amount decreased with the temperature raising, but interlayer spacingof MMT enlarged gradually. The intercalative process was considerated by control ofentropy mainly and influenced by temperature notablely. Gelatin modified bysalicylaldehyde and/or methanol could still intercalate into MMT interlayers. Theintercalative spacings are all above 3nm. Gelatin could intercalate into MMT that wasmodified by sodium dodecyl sulfate or lysine, but the intercalative effect is not asgood as unmodified MMT, suggesting that MMT modified by low molecules is notsuitable for the system of gelatin-MMT intercalation.