Maleic anhydride copolymers base hydrolysis

Scheme 6.4 Base-catalyzed hydrolysis reactions of an anhydride group in a copolymer of styrene and maleic anhydride, which renders the latter soluble in water.

To synthesize polynucleotide analogues closely resembling natural polymers, we have synthesized several new monomers such as dihydrofuran and dihydropyran derivatives which contained nucleic acid bases (Scheme 1). Copolymerization of the monomers either with maleic anhydride or with vinylene carbonate resulted in the alternating copolymers as shown in Scheme 2. Hydrolysis of the products gave the polymers which were optically active and soluble in water and had alternating sequences along the polymer chain. In this paper we will report synthesis of monomers, their copolymerization either with maleic anhydride or with vinylene carbonate, hydrolysis of the copolymers, and the physicochemical properties of the anhydride and hydrolyzed polymers. 

Polymeric films based on maleic copolymers are used for enteric, ocular, and trans-dermal drug delivery (Table 10.5) because they were proved to be bioadhesive and mucoadhesive [151-153], Loaded films can be prepared by dissolving the drug and the copolymer in anhydride form in organic solvents (acetone-water mixture, isopropanol, 2-butanol) and casting [139,154-159]. Water can also be a solvent for the formation of the films/hydrogels, but in this case the hydrolysis of the maleic copolymer takes place before the contact with the body [151-153,160-162]. 

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