title: Effect of aggregation behavior of gelatin in aqueous solution on the grafting density of gelatin modified with glycidol.
abstract: The effect of aggregation behavior of gelatin in aqueous solution on the grafting density of glycidol grafted gelatin polymers (GGG polymers) was investigated. The grafting density was measured using the Van Slyke method by calculating the conversion rate of free - NH(2) groups of gelatin. The conversion rate reached peak values at 6% and 14% of the gelatin aqueous solution. SEM micrographs displayed a series of structural transitions (i.e., spherical, spindle, butterfly, irregular and dendritic aggregates) at varying concentrations from 2% to 16% (w/w) at an interval of 2% (w/w). The spindle aggregates reappeared at the concentrations of 6% and 14%. Viscosity measurements indicated that the physicochemical properties of the gelatin solution had changed with increasing concentration. UV and CD analysis indicated that hydrophobic interactions competed with hydrogen bonding, and the random coils partly transformed to β-sheet structure by changing the concentration. Zeta potential and pH data confirmed the increasing electrostatic repulsion associated with increasing the hydrophobic region. XPS analysis revealed that the elemental composition of the gelatin particle surface changed with variation in the aggregate structure, determining the monotonic variation of the grafting density with increasing concentration. Results demonstrate that aggregation behavior of gelatin in aqueous solution plays a crucial role in deciding the grafting density of gelatin modified products.
authors.affiliation: School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122, PR China.
authors.forename: Jing
authors.initials: J
authors.lastname: Xu
authors.forename: Tian-Duo
authors.initials: TD
authors.lastname: Li
authors.forename: Xiao-Long
authors.initials: XL
authors.lastname: Tang
authors.forename: Cong-De
authors.initials: CD
authors.lastname: Qiao
authors.forename: Qing-Wei
authors.initials: QW
authors.lastname: Jiang
mesh_terms: D004852:Epoxy Compounds / Q000737:chemistry*; D005780:Gelatin / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D010316:Particle Size; D011108:Polymers / Q000737:chemistry*; D020005:Propanols / Q000737:chemistry*; D012996:Solutions; D013499:Surface Properties; D014867:Water / Q000737:chemistry
chemical_list: D004852:Epoxy Compounds; D011108:Polymers; D020005:Propanols; D012996:Solutions; D014867:Water; D005780:Gelatin; C004312:glycidol