The reaction is preferably carried out at temperatures less than about 60??? C. Typical water soluble initiators that can provide radicals at such temperatures include thermal initiators, including persulfates, such as potassium persulfate, and 2,2'-azobis (2-amidinopropane) dihydrochloride, redox couples, including persulfate and silver salt couples such as potassium persulfate and silver nitrate