Ink-Jet Printing of High-Molecular-Weight Polymers in Oil-in-Water Emulsions

Ink-jet printing of high-molecular-weight polymers is inhibited by the extensional elasticity of the polymer chains. This article describes how emulsions can be used to print high-molecular-weight polymers at much higher concentrations than is possible in a binary solution. The polymers are dissolved in the dispersed phase of an oil-in-water emulsion. The surface tension of the oil-water interface opposes deformation of the oil droplets during ejection from the nozzle and leads to the extensional strain occurring in the polymer-free continuous phase. We show that a solution of polystyrene (PS) (M_n = 419 kDa, polydispersity index = 1.21) can be printed at an overall concentration of 3.8 wt % in a sodium dodecyl sulfate-stabilized emulsion of methyl benzoate in water, an order of magnitude higher in concentration than previously reported for PS dissolved in binary solutions [ Hoath , S. D. , Harlen , O. G. , and Hutchings , I. M. J. Rheol. 2012 , 56 ( 5 ), 1109 - 1127 ]. Factors influencing the formulation of emulsions for ink-jet printing of polymers are discussed.