p selected from the group consisting of an aromatic group, an aliphatic group, a cyclic aliphatic group, and a combination of the aromatic group and the aliphatic group, or substituents thereof, R4 is a tetravalent group selected from the group consisting of an aromatic group, an aliphatic group, a cyclic aliphatic group, and a combination of the aromatic group an the aliphatic group, or substitue