RADICAL METHYL-METHACRYLATE METHACRYLIC-ACID COPOLYMERIZATION IN ISOPROPYL-ALCOHOL, ACETONE, AND THEIR MIXTURES - APPLICATION OF THE COPOLYMER PRODUCTS FOR MICROENCAPSULATION OF AMPICYLLINE TRIHYDRATE

The copolymerization ratios of radical methyl methacrylate (MMA) metha crylic acid (MA) copolymerization in mixtures of isopropyl alcohol (IP A) with acetone (A), xylene (X), and water (W) are determined. Their v alues and those in IPA are smaller than unity. The established alterna ting tendency of the monomer parts in the obtained copolymers is somew hat larger than the theoretically expected one and this is explained b y the donor-acceptor interaction either between comonomers or between them and the propagating radicals. It is suggested that the reason for this tendency is the difference in H-bond formation between comonomer s and solvents used. The dependencies of the apparent mass average mol ecular weight of the copolymers (M(w,ap)BAR on their composition are a lso determined as well as the theta-composition of the A-heptane (H) m ixture for these copolymers. These data are used for ampicylline trihy drate (AT) microencapsulation by phase separation of the AT suspension in copolymer solutions in A after H addition. The AT microencapsulati on characteristics (yield, degree and efficiency) as dependent on the copolymer composition as well as the influence of this composition on the solution kinetics of the microencapsulated AT at pH = 4.5 and 6.5 and temperature of 37-degrees-C are established.