{HEAD ~ Another example} is {TAIL ~ condensation polymers} having covalently bonded as repeating units in the polymer chain, aromatic tetracarbonylbisimide groups of the formula II and III 
is
{ HEAD ~ Another example } is { TAIL ~ condensation polymers } having covalently bonded as repeating units in the polymer chain , aromatic tetracarbonylbisimide groups of the formula II and III
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