Hydrophobically Modified Alginate for Enhancing the Dispersibility of SDS to CuPc Pigment Colorant in Water

In this research, sodium alginate (SA) was first oxidized by sodium periodate to convert its 1,2-hydroxyl into aldehyde groups. Then, the cinnamamide was grafted with it through a mild Schiff reaction to get the hydrophobically modified SA (HMSA). The structure of HMSA was determined by FT-IR, 1H-NMR, and XPS analysis. Subsequently, it was utilized to improve the dispersibility of sodium dodecyl sulfate (SDS) to copper phthalocyanine pigment (CuPc) in aqueous medium. It was found that when the addition amount accounted for 30% of SDS, HMSA could make the dispersion obtain the best settlement stability. In addition, the addition of HMSA could significantly improve the dispersion stability to different pH and temperatures. The results of Turbiscan Stability Index (TSI) measurement directly indicated that the TSI index of the CuPc dispersion by SDS/HMSA was lower than that by SDS alone. SDS and HMSA could form an SDS/HMSA composite through hydrophobic interactions or hydrogen bond forces to produce both steric and electric repulsive forces for better stability of CuPc dispersion.