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In the case of a monomer having a hydroxyl group, the hydroxyl group may be replaced by an acetal group suscep- tible to deprotection with acid, typically ethoxyethoxy, prior to polymerization, and the polymerization be followed by deprotection with weak acid and water. Alternatively, the hydroxyl group may be replaced by an acetyl, formyl, pivaloyl or similar group prior to polymerization, and the polymerization be followed by alkaline hydrolysis. 

The polymer may further comprise recurring units of at least one type selected from recurring units having the formula (dl), recurring units having the formula (d2), and recurring units having the formula (d3). These recurring units are referred to as recurring to units (dl), (d2) and (d3), respectively. 

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