Modified Polyurethanes With Synthetic Organosilicon Bi-quaternary Ammonium

Organosilicon bi-quaternary ammonium is a new class of surfactants from developed materials, which combines the advantages of traditional Gemini surfactants and organosilicon surfactants. Therefore, it has higher surfactivity, wettability and antimicrobial properties than traditional surfactants. Although cationic waterborne polyurethane (WPU) inherited waterborne polyurethane the advantages of non-flammable, non-toxic, anti-bacterial, dust-free, environment-friendly properties, the thermodynamic stability, water resistance and mechanical properties of its film is very poor. Those properties can be improved by using modifying agent of polysiloxane.A series of organosilicon bi-quaternary ammonium amphiphiles, [OHsC3(C2H5)2 N+-(CH2)3-Si(CH2)3-O-(Si(CH3)2O)n-Si(CH2)3-(CH2)3-N+(C2H5)2C3H5O].Cl2- and [HO-H6C3(C2H5)2N+-(CH2)3-Si(CH2)3-O-(Si(CH3)2O)n-Si(CH2)3-(CH2)3-N+(C2H5)2C3H6.OH] Cl2-, 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< SioN2Cl2. At the same time, thermodynamic parameters (△G0m, △H0m, △S0m) of micellization were calcμlated 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 molecμlar 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.A series of cationic waterborne polyurethane modified by above organosilicon bi-quaternary ammonium has been synthesized. And the influence of various facors in the process has been detailed dicussed. Studies have shown that with the increase of the content of the weight of organosilicon quaternary ammonium Gemini, the stability of emμlsion will be enhanced firstly, and then weaken, but the thermodynamic stability,surface hydrophobic and antimicrobial property of its film will be will be always enhanced. Its antimicrobial property of Gram-positive is superior to the antibacterial properties of Gram-negative bacteria. Besides, the water resistance can be improved to an extent.