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| PATENT EXAMPLES |
To prepare the CPP polymer 40 grams of CPP powder was added to 500 ml boiled acidic anhydride at approximately 130 degrees C. under dry nitrogen reflux. The reaction was stopped after 15 min. and the solution was filtered through a filter paper to another 1 liter round bottom flask. The solution was then concentrated to 150 ml by evaporation. The solution was allowed to crystallize which was then separated by filtration and transferred to 200 ml of anhydrous diethyl ether in an erlenmeyer flask and allowed to swirl for several hours at room temperature. The white crystals were separated by filtration and dried in a calcium chloride desicator under vacuum. It is essential that the degree of polymerization of the prepolymer not be greater than 4 by G.C.P. EXAMPLE III A high molecular weight copolymer of 1.3 bis (p-carboxyphenoxy)propane:dodecanedioic acid was prepared using the pure isolated CPP prepolymer as in Example I. A dodecandioic acid prepolymer was prepared by adding 5.0 grams of dodecanedioic acid to 250 ml boiling acetic anhydride under dry argon and refluxed for 60 minutes. The excess acetic anhydride was removed by an evaporator at 60 degrees C. to yield a white solid which was dissolved in 20 ml dry toluene and allowed to crystallize overnight at 0 degrees C. The crystals were separated by filtration and extracted with 200 ml methyl ether and petroleum ether 1:1 mixture for 5 hours at room temperature. The pure crystals were then dried under vacuum over calcium chloride to yield 47 grams of prepolymer with a melting point of 76 degrees C. A CPP:DD 20:80 polyanhydride copolymer was prepared by mixing 0.8 grams CPP prepolymer with 2.0 grams dodecanedioic acid prepolymer and polymerized at 180 degrees C. for 90 minutes under high vacuum (less than 10.sup.-2 mm Hg). The high molecular weight copolymer was purified as previously described and had a melting point of 70 to 76 degrees C., a weight average molecular weight of 125,900 and an intrinsic viscosity of 1.16 dl/g. |
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