Hydrophilicity modification of polyphenylene sulfide: A comparative study on the introduction of Zr by physical blending and copolymerization

Abstract

Polyphenylene sulfide (PPS) is widely used in auto components, machinery parts, electrical accessories, and anti-corrosion coatings, but its hydrophobicity restricts its application in biomaterials, medical equipment, battery separators, and oil pollution separation membranes. To improve the hydrophilicity of PPS, zirconium oxynitrate reacted with 3,5-dichlorosalicylic acid (SA) to generate zirconium-carboxylate (ZrSA). ZrSA was then incorporated into the main chain of PPS through copolymerization to yield hydrophilic copolymers (ZrSA-PPS). Meanwhile, SA was copolymerized into the main chain of the PPS to produce SA-PPS. Next, SA-PPS and ZrO2 were physically blended to obtain hydrophilic composites (ZrO2/SA-PPS). The melting point of ZrSA-PPS ranged from 278.19 to 281.16 °C, which was slightly higher than that of ZrO2/SA-PPS (278.39–279.95 °C), but its crystallinity (34.3–41.2 %) was lower than that of ZrO2/SA-PPS (42.2–51.6 %). The maximum decomposition temperatures of ZrSA-PPS and ZrO2/SA-PPS were increased by about 10 °C, indicating that the Zr–O bonds obstruct the thermally induced movements of the molecular chain. The ZrSA-PPS possessed a tensile strength of 40.8–70.5 MPa and a flexural strength of 46.4–103.4 MPa. The tensile and flexural strengths of ZrO2/SA-PPS (14.6–65.1 Mpa and 23.1–100.3 Mpa) were significantly inferior to that of ZrSA-PPS. This revealed that the ZrSA cross-linked structure can prevent crack propagation. The water contact angle of ZrSA-PPS and ZrO2/SA-PPS were ranged from 59.0° to 76.5° and 61.6°–78.5° (Neat-PPS, ∼87.9°), respectively. The agglomeration of ZrO2 resulted in a slightly higher water contact angle for ZrO2/SA-PPS than for ZrSA-PPS. The enhanced hydrophilicity of ZrSA-PPS benefited from the formation of large chain spacing, strong polar groups, and hydrogen bonds. Our study may shed light on the hydrophilic modification of PPS, which should offer a valuable guide and option for PPS in hydrophilic applications.