YANG+Chao

【Abstract】We added Cellulase into the SDS solution for enhancing its dispersion ability to CuPc in terms of their synergistic actions.The optimal mass ratio of SDS/cellulase was determined to be 9：1 by dispersibility measurement. The surface modification of CuPc of SDS/cellulase was confirmed by TG analysis.

【Key words】SDS；Cellulase；CuPc pigment

0 Introduction

Phthalocyanine pigment has a larger particle size and strong hydrophobicity so that it has to be properly surface modified with a dispersant when dispersed into the aqueous phase[1-2].Anionic surfactant is an amphipathic small molecule substance that can significantly reduce the surface tension of water and change the surface or interface state of the system to produce many functions such as wetting. Cellulose enzyme molecules have separated hydrophobic and hydrophilic regions in the molecule， thus it could exhibit unique colloidal properties which provide adequate stabilization of static electricity and sterically to pigments[3-4].

Anionic surfactants could cooperate with cellulases and the sizes of the two molecular are synergistic. They can play a synergistic role in the dispersion of organic pigments， and the overall performance of them exceeded single using of each other.

1 Materials and methods

1.1 Materials

SDS， cellulase and CuPc pigments were purchased from Aladdin Reagent Co.， Ltd.

1.2 Synergistic dispersion of CuPc pigment with SDS / cellulase

Prepared 6g/L SDS/cellulase solution， adjust the mass ratio of anionic surfactant and cellulase， then added 60g / L CuPc， then dispersed solution in ultrasonic crusher for 20min.

1.3 Measurements

Centrifugal stability of pigment： dispersion and stability of CuPc dispersion was measured with spectrophotometric.

TG： The pigment to be measured was heated from 25°C to 600°C at a rate of 20°C/min in a N2 atmosphere.

2 Results

2.1 Synergistic dispersing CuPc pigment by SDS / cellulase

The effect of the mass ratio of SDS/cellulase on the dispersibility of CuPc was shown in Fig1.As we could see， when the mass ratio of SDS to cellulase was 9：1， the absorbance of the pigment dispersion reaches the highest0.448，which indicated that the dispersibility of the pigment is best at this time.As a biomacromolecule polyelectrolyte，cellulases have hydrophobic groups that bind tightly to organic pigments and their hydrophilic groups provide steric hindrance to dispersed pigments. At the same time， the hydrophobic residues of the protein and the surfactant would bond and act after the combination of cellulase and SDS，which promoting the ionization of the amino and carboxyl groups of the peptide chain.endprint

Fig1 Effect of SDS / cellulase on the dispersivity of CuPc

Stability is also an important mark to measure dispersibility of pigment， and we used centrifugal stability to characterize. As we can see in Fig 2， with the speed of centrifugation increased， the absorbance of both SDS system and SDS / cellulase system decreases， but the absorbance of SDS / cellulose dispersion liquid is always higher than pure SDS system. The reason of the results was that the presence of the protein not only enhanced the steric effect but also introduced an electrostatic effect which prevented aggregation of the pigment particles so that they were retained by the small-sized particles and the dispersion was more stable.

Fig2 Centrifugal stability of CuPc dispersion

—SDS-based pigment；—SDS/ cellulase-based pigment

2.2 Thermogravimetric analysis

To sum up， the dispersibility of SDS/cellulase-based pigment was better than SDS-based pigment. Modification of pigment particles by dispersants can be analyzed by thermogravimetric measurement. Fig3 shows that the original pigment had no significant weight loss before 200 ° C， indicating that the sample does not already contain absorbed water and bound water. There was no significant loss of weight before 425°Cindicated that original pigment showed better thermal stability. The SDS/cellulase-based pigment started to lose weight significantly at 200°C， which caused by pyrolysis of SDS and Proteolysis. The phenomenon proved that SDS/Cellulose have combined with CuPc pigments， and attached to the pigment particle surface.

Fig3 Thermogravimetric curves of CuPc pigments

1—Original pigment；2—SDS / cellulase-based pigment

3 conclusion

Synergistic dispersing CuPc pigment using SDS/cellulase has a better synergistic effect.The optimal mass ratio was 9：1 at which pigment had the best dispersion and centrifugal stability.

【References】

[1]ERK P.Crystal design of organic pigments-a prototype discipline of materials science[J].Current Opinion in Solid State and Materials Science， 2001，5（2）：155-160.

[2]SIS H， BIRINCI M. Wetting and rheological characteristics of hydrophobic organic pigments in water in the presence of non-ionic surfactants[J].Colloids and Surfaces A： Physicochemical and Engineering Aspects，2014，455：58-66.

[3]GELAMO E L，TABAK M. Spectroscopic studies on the interaction of bovine （BSA） and human （HSA） serum albumins with ionic surfactants[J].Spectrochimica Acta Part A：Molecular and Biomolecular Spectroscopy， 2000，56（11）：2255-2271.

[4]FOLMER B，HOLMBERG K，SVENSSON M.Interaction of Rhizomucor miehei lipase with an amphoteric surfactant at different pH values[J].Langmuir，1997，13（22）：5864-5869.endprint