stirring is heated to a temperature between about 80 u00b0 c and about 150 u00b0 c preferably about 114 u00b0 c and maintained at this temperature until ammonia gas is no longer emitted from the reaction mixture the reaction mixture comprising a copolymer composed of dimethylsilane and urea units has a viscous opaque appearence the mole ratio of urea to cyclosilazanes is generally between about 1 1 and about 2 1 preferably about 1 1 the amount of ammonium bromide catalyst that is used in this reaction is generally between about 0 1 and about 3 grams per 100 ml of reaction solution thereafter the reaction mixture is heated at constant temperature for an additional period of at least 15 minutes to ensure completion of the polymerization reaction then cooled to a temperature between about 50 u00b0 c and about 100 u00b0 c preferably about 80 u00b0 c prior to addition of the penicillin sulfoxide thereafter penicillin sulfoxide is added directly into the reaction flask containing the copolymer along with an organic ammonium salt catalyst the reaction was then heated to a temperature between about 80 u00b0 c and about 150 u00b0 c preferably about 114 u00b0 c for a period ranging between about 30 and about 60 minutes preferably about 30 minutes during which time the ring expansion reaction occurs the amount of organic ammonium salt catalyst that is employed in the ring expansion reaction is generally between about 1 and about.