Film Morphology, Orientation And Structure-Activity Relationship Of Amino Polysiloxanes

Amino polysiloxanes are special materials that impart desired mechanical performance properties of fabrics such as softness,smoothness,bounciness and antiwrinkle properties.This paper researched on the surface morphologies,orientation and structure-activity relationship of amino polysiloxanes.Amino polysiloxanes were synthesized byα,ω-dihydroxypolydimethylsiloxane and five kinds of amino silane coupling agent under alkaline catalysts.The amino values were controlled by adjusting the amount of silane coupling agents,and the chemical structures were determined through ¹H-NMR spectrograms.The orientation model of amino polysiloxane molecule was proposed that the amino functional groups adsorb onto the cellulose interface while the main polymer chains and the hydrophobic Si-CH₃ groups extend toward the air.A series of amino polysiloxanes with different amino values were adsorbed onto surfaces of cotton fibers and cellulose substrates.The film morphologies were investigated by field emission scanning electron microscope(FESEM) and atomic force microscope(AFM).The results indicated that the amino polysiloxane can form a hydrophobic film on both cotton fibers and cellulose substrates and the surface roughness decreased from 4.771nm to 1.876nm.Furthermore,the roughness becomes smaller with an increase in the amino value.The surface compositions of the amino polysiloxanes were characterized by X-ray photoelectron spectroscopy(XPS) and attenuated total reflectance infrared(ATR-IR). The results further verified the orientation model of amino polysiloxane.The relationships between amino polysiloxanes' structure and their performance were researched and the results indicated that amino values and amino types of the amino polysiloxanes have significant impacts on fabric performance.Amino polysiloxanes with moderate amino values exhibit excellent softening property.For amino polysiloxanes with two amino groups on one coupling agent,the moderate amino value is 0.6mmol/g.For amino polysiloxanes with only one amino group on one coupling agent,the moderate amino value is 0.4mmol/g.The amino polysiloxanes with relatively high amino values exhibit superior smoothening property.The order of fabric handle imparted by amino polysiloxanes with different amino types,from most to least satisfactory,is:tertiary amino,secondary amino,primary amino.The amino polysiloxanes with high steric hindrance give unsatisfactory fabric performance while the amino polysiloxanes with smooth surface morphologies exhibit superior smoothening property.