Use of viscosity as an in-line diagnostic for high internal phase emulsion generation

A process for the preparation of a porous cross-linked polymeric material comprising the steps of:

• (a) providing a water phase comprising water and an electrolyte;
• (b) providing an oil phase comprising a mixture of polymerizable monomers comprising at least one vinyl monomer and a crosslinker;
• (c) providing a surfactant to the water phase, the oil phase, or both the water and the oil phases;
• (d) combining and mixing said water phase and said oil phase in a mixer under conditions effective to produce an emulsion having at least 90 weight percent, based on the emulsion, of water as the internal phase;
• (e) providing a capillary for receiving the emulsion output of said mixer, said capillary having segments of different diameters;
• (f) maintaining said emulsion at a preselected temperature as it flows through said capillary to a capillary output;
• (g) measuring the pressure drop across selected lengths of each of said different diameter segments;
• (h) utilizing the pressure drop to adjust operating conditions to produce a porous cross-linked polymeric material;
• (i) adding to at least a portion of said oil phase, water phase or emulsion, an effective amount of a polymerization catalyst to cure the polymerizable monomers;
• (j) polymerizing said emulsion from said capillary output under conditions effective to cure the polymerizable monomers;
• and
• (k) removing at least a portion of the water from said cured emulsion.