A stable concentrated inverse polymer emulsion (CIPE) was prepared using ternary monomers of acrylic acid

acrylamide and 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS)

with Span-80 and Tween-60 as complex emulsifiers in the presence of a redox initiator system at room temperature.As a control

a common emulsion with a low volume fraction of dispersed phase and a pseudo CIPE obtained from the centrifuge of the common emulsion were also prepared.The morphology of latex particles was observed under an optic microscope and the size and its distribution were statistically figured out.Images show CIPE has smaller particles entrapped among the larger ones

and the characteristic analysis of CIPE exhibits a dual peak distribution of latex sizes

as sharp contrast to the single peak distribution for both the other emulsions.It was proposed that these small particles functioned as a wedge

effectively reducing the stress exerted on the large particles and enhancing the CIPE stability.A series of experiments testified the wedge effect.The apparent complex modulus of CIPE is 3-fold higher than that of the pseudo CIPE in terms of a dynamic rheological technique though both the emulsions have the same volume fractions.Furthermore

CIPE demonstrates high stability under hyperacoustic and thermal treatment compared with both the pseudo CIPE and the common emulsion.These observations provide a proof that CIPE displays a high stability with the characteristic structure of dual peak and the wedge effect thereof.