title: Effect of siloxane spacer length on organosilicon bi-quaternary ammonium amphiphiles.
abstract: A series of organosilicon Bola-form bi-quaternary ammonium amphiphiles, [OH5C3(C2H5)2N+-(CH2)3-Si(CH2)3-O-(Si(CH3)2O)n-Si(CH2)3⋯(CH2)3-N+(C2H5)2C3H5O]Cl2- (SinN2Cl2, n=0, 4, 6, 8), with the same headgroups and different length of hydrophobic linkage has been synthesized. The critical micelle concentration (CMC) of each amphiphiles was determined by equilibrium surface tension. With the increased length of hydrophobic siloxane spacer, the CMC values follow the order of Si8N2Cl2<Si6N2Cl2<Si4N2Cl2<Si0N2Cl2. At the same time, thermodynamic parameters (ΔGm0, ΔHm0, ΔSm0) of micellization were calculated by Gibbs equation under the mass action model. It indicates that the micellization of the amphiphiles in aqueous solution is entropy-driven. Especially, the surface area (Amin) of Si4N2Cl2 is the largest attributing to the interaction of free-rotated siloxane spacer and its internal oxygen atom, which make the molecular stretch free. The antimicrobial property of Si4N2Cl2 is more effective than others below the concentration of CMC, while the antimicrobial property of Si8N2Cl2 is more effective above the concentration of CMC, which indicated that both the adsorbability in formation of micellar and the hydrophobicity arising from the different length of siloxane spacer are important to inhibit microbe. Moreover, their wetting ability has been characterized by contact angles on various material surfaces. It shows that the higher weight of lipophilic siloxane spacer leads to lower contact angels.
authors: Shandong Provincial Key Laboratory of Fine Chemicals, Qilu University of Technology, Jinan 250353, China.
authors: Chuanming
authors: C
authors: Hao
authors: Shandong Provincial Key Laboratory of Fine Chemicals, Qilu University of Technology, Jinan 250353, China.
authors: Yuezhi
authors: Y
authors: Cui
authors: Shandong Provincial Key Laboratory of Fine Chemicals, Qilu University of Technology, Jinan 250353, China.
authors: Pengfei
authors: P
authors: Yang
authors: Shandong Provincial Key Laboratory of Fine Chemicals, Qilu University of Technology, Jinan 250353, China.
authors: Huayong
authors: H
authors: Zhang
authors: School of Food & Bioengineering, Qilu University of Technology, Jinan 250353, China.
authors: Dejiang
authors: D
authors: Mao
authors: Shandong Provincial Key Laboratory of Fine Chemicals, Qilu University of Technology, Jinan 250353, China.
authors: Xiao
authors: X
authors: Cui
authors: Shandong Provincial Key Laboratory of Fine Chemicals, Qilu University of Technology, Jinan 250353, China; School of Marine Science and Engineering, Tianjin University of Science and Technology, Tianjin 300457, China. Electronic address: xiaozhexie@163.com.
authors: Junying
authors: J
authors: Li
mesh_terms: D000890:Anti-Infective Agents / Q000138:chemical synthesis* / Q000494:pharmacology; D001412:Bacillus subtilis / Q000187:drug effects / Q000254:growth & development; D004553:Electric Conductivity; D004926:Escherichia coli / Q000187:drug effects / Q000254:growth & development; D057927:Hydrophobic and Hydrophilic Interactions; D008823:Micelles; D008826:Microbial Sensitivity Tests; D020075:Phanerochaete / Q000187:drug effects / Q000254:growth & development; D000644:Quaternary Ammonium Compounds / Q000138:chemical synthesis* / Q000494:pharmacology; D012833:Siloxanes / Q000737:chemistry*; D013211:Staphylococcus aureus / Q000187:drug effects / Q000254:growth & development; D013329:Structure-Activity Relationship; D013500:Surface Tension; D013501:Surface-Active Agents / Q000138:chemical synthesis* / Q000494:pharmacology; D013816:Thermodynamics; D017155:Wettability
chemical_list: D000890:Anti-Infective Agents; D008823:Micelles; D000644:Quaternary Ammonium Compounds; D012833:Siloxanes; D013501:Surface-Active Agents
keywords: Bi-quaternary; Bola amphiphiles; Organosilicon surfactants