Effect of ester side chains on the aggregation state and surface properties of poly(dialkylfumarate)s

The aggregation state and surface properties of poly(dialkylfumarate)s (PDAFs) with various alkyl ester groups have been studied by X-ray diffraction, dynamic viscoelastic measurements, contact angle analysis, and X-ray photoelectron spectroscopy (XPS). PDAFs in the rigid rod-like molecular structure showed the mechanical α-absorption behavior in a temperature range above 450 K, which was attributed to the glassy-rubbery phase transition. The β-absorption behavior was apparently dependent on the bulkiness of the ester side chain. The intermolecular distance of rigid rod like molecules increased with the number of carbon atoms in the bulky ester group. The angular dependent XPS and contact angle measurements revealed that the polymers have low surface free energy due to the orientation of hydrophobic alkyl chains around the core composed of backbone chain.