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Cutter, L. A. in U.S. Pat. No. 4,145,375 presents a process for copolymerizing styrene and maleic anhydride which involves a sequence of operations in which maleic anhydride is first gradually admixed with styrene in a mass stage under polymerizing conditions to rapidly form styrene-maleic anhydride polymer. The styrene-rich mixture is then suspended in water and the styrene polymerization completed as in a conventional mass/suspension polymerization system. The suspension step further modifies the polymer by opening the anhydride group to form free carboxylic acid groups on the polymer chain. Following the heating period, the polymerization mixture is cooled; the polymer beads are separated from the water by a solid-bowl centrifuge, and dried in a rotary air drier. The polymers resulted have Mw=100,000-500,000, and the content of residual styrene is between 0.02 and 0.1% by weight. A disadvantage of this process is that the final product is a blend of polystyrene and SMA copolymer, the polystyrene being a major contaminant, with multiple implications making it unfavorable for bio-applications. Similar problems exist for front polymerization which uses excess of styrene. Szalay, J. et al., Macromol. Rapid Commun. 1999, 20, 315-318.