Is heat capacity larger for polymers?
Yes, because polymers are covalently bonded material, and metals are metallic bonded material.
Covalent bonds do not let atoms exchange electrons like metallic bonds do. The highest heat capacity values are found in linear and branched polymers because the secondary intermolecular bonds are weak, and there is a minimum of cross-linking. With increased cross-linking, the magnitude of the expansion coefﬁcient diminishes; the lowest coefﬁcients are found in thermosetting network polymers
such as phenol-formaldehyde, in which the bonding is almost entirely covalent.