Enhancing hydrophilicity of polyethylene terephthalate surface through melt blending

Abstract

In many industrial sectors, the surface properties of polymers are of particular importance. This applies, for instance, to painting, printing, and any coating on surface of polymeric objects. Hydrophilicity and wettability characteristics are known to be determined by the chemical makeup of the polymer surface. Blending with an additive or a polymer containing high-energy functional groups is widely recognized as a potential technique to overcome disadvantages of low surface energy of polymers due to its convenient processing. Surface migration of polyethylene glycol (PEG) in Polyethylene Terephthalate (PET) host was investigated using a low-molecular-weight PEG (8 kDa) because of its good hydrophilicity, low toxicity, biocompatibility, and chain mobility. A twin-screw extruder was used to blend the materials and prepare the polymer blend films. The results of surface characterizations showed that PEG renders the PET surface more hydrophilic, but not high enough for many applications. In a second approach, the addition of a third component, polystyrene (PS), to the blend in a small amount resulted in a remarkable surface enrichment of PEG at the polymer/air interface for the ternary polymer blend (PET-PEG-PS). Surface analysis revealed that the surface concentration of PEG in the ternary polymer blend film was significantly larger than that of the binary one. POLYM. ENG. SCI., 55:349–358, 2015. © 2014 Society of Plastics Engineers