Role of emulsifier on the particle size and polymer particle size distribution using multiwavelength spectroscopy measurements

ABSTRACT

Latex emulsions depend strongly on the polymer composition, and particle size distribution, which in turn, is a function of the preparation of the latex and on the formulation and composition variables. This study reports measurements of particle size and particle size distribution of latex emulsions as function of the reaction time and the type and concentration of emulsifier by using the multiwavelength spectroscopy technique. Results show changes in the particle size of latex emulsions with the reaction time, obtaining larger particles and broader distributions with increasing of Tween 80 ratio. The steric stabilization provides the sole nonionic emulsifier is not enough to protect the polymer particle, causing the flocculation among the interactive particles, resulting in unstable latex. However, latex emulsions prepared with Tween 80 ratio <70 wt.% can stabilize efficiently the nucleated particles, probably due to the effects provided by both, the electrostatic and steric stabilization mechanisms. The same effect is shown in the curves of conversion (%) as a function of reaction time, resulting in slower polymerization rate for Tween 80 ratio >70 wt.%. On the other hand, smaller polymer particles, in all range of emulsifier mixture, have been obtained to higher emulsifier concentration.

GRAPHICAL ABSTRACT

KEYWORDS:

• Emulsion polymerization
• emulsions
• multiwavelength spectroscopy
• particle characterization
• polymer particle size

Abbreviations:

• Au, absorbance units
• UV-Vis, ultraviolet-visible
• cmc, critical micellar concentration
• PSD, particle size distribution
• SDBS, sodium dodecyl benzene sulfonate
• Np, number of particles

Acknowledgments

The authors thank to the Universidad de Los Andes Research Council (CDCHTA- Grant N° I-1319-12-08A) for sponsoring the research program at the POLYCOL (Polymers and Colloids) laboratory.