nonionic dispersants or surfactants such as sodium dodecyl sulfate sodium dioctyl sulfosuccinate sodium dodecylbenzenesulfonate ethoxylated allkylphenols such as ethoxylated nonylphenols and ethoxylated fatty alcohols lauryl pyridinium bromide polyether phosphates and phosphate esters modified alcohol ethoxylates and combinations thereof the blocking agent for isocyanate groups may be either a monofunctional alcohol or a monofunctional amine the blocking agent may be added at any time prior to formation of the prepolymer during the formation of the prepolymer or after the formation of the prepolymer including before and after dispersing the prepolymer into an aqueous medium such as deionized water in some embodiments the blocking agent is optional or may be excluded in other embodiments based on the weight of the prepolymer the blocking agent may be included in an amount from about 0 05 to about 10 0 including about 0 1 to about 6 0 and about 1 0 to about 4 0 based on the weight of the final dispersion the blocking agent may be present in an amount from about 0 01 to about 6 0 including about 0 05 to about 3 and about 0 1 to about 1 0 the inclusion of a blocking agent permits control over the weight average molecular weight of the polymer in the dispersion as well as providing control over the polymer molecular weight distribution the effectiveness of the blocking agent to provide this control depends on the type of the blocking agent and when the blocking agent is added during the preparation of the dispersion for example a monofunctional alcohol may be added prior to the formation of the prepolymer during or after the formation of the.