title: Aggregation behaviors of gelatin with cationic gemini surfactant at air/water interface.
abstract: The dilational rheological properties of gelatin with cationic gemini surfactant 1,2-ethane bis(dimethyl dodecyl ammonium bromide) (C(12)C(2)C(12)) at air/water interface were investigated using oscillating barriers method at low frequency (0.005-0.1 Hz), which was compared with single-chain surfactant dodecyltrimethyl ammonium bromide (DTAB). The results indicate that the maximum dilational modulus and the film stability of gelatin-C(12)C(2)C(12) are higher than those of gelatin-DTAB. At high concentration of C(12)C(2)C(12) or DTAB, the dilational modulus of gelatin-surfactant system becomes close to that corresponding to pure surfactant, suggesting gelatin at interface is replaced by surfactant. This replacement is also observed by surface tension measurement. However, it is found that gelatin-C(12)C(2)C(12) system has two obvious breaks but gelatin-DTAB has not in surface tension isotherms. These phenomena are ascribed to the double charges and strong hydrophobicity of C(12)C(2)C(12). Based on these experimental results, a mechanism of gelatin-surfactant interaction at air/water interface is proposed.
authors.affiliation: Key Laboratory of Colloid & Interface Chemistry (Shandong University), Education Ministry, Jinan 250100, PR China.
authors.forename: Dan
authors.initials: D
authors.lastname: Wu
authors.forename: Guiying
authors.initials: G
authors.lastname: Xu
authors.forename: Yujun
authors.initials: Y
authors.lastname: Feng
authors.forename: Yiming
authors.initials: Y
authors.lastname: Li
mesh_terms: D000388:Air; D002412:Cations / Q000737:chemistry; D004548:Elasticity; D005780:Gelatin / Q000737:chemistry*; D020836:Protein Structure, Quaternary; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D012996:Solutions; D013500:Surface Tension; D013501:Surface-Active Agents / Q000737:chemistry*; D014783:Viscosity; D014867:Water / Q000737:chemistry*
chemical_list: D002412:Cations; D000644:Quaternary Ammonium Compounds; D012996:Solutions; D013501:Surface-Active Agents; D014867:Water; C013912:decyltrimethylammonium; C031848:N,N'-bis(dodecyldimethyl)-1,2-ethanediammonium; D005780:Gelatin