Effects of lithium perchlorate on the nucleation and crystallization of poly(ethylene oxide) and poly(ε-caprolactone) in the poly(ethylene oxide)–poly(ε-caprolactone)–lithium perchlorate ternary blend

Abstract

The effects of lithium perchlorate (LiClO4) on the nucleation and crystallization of poly(ethylene oxide) (PEO) and poly(ε-caprolactone) (PCL) in the PEO–PCL–LiClO4 ternary blend were studied by using a polarizing optical microscope (POM), differential scanning calorimetry (DSC) and Fourier transformation infrared spectroscopy (FTIR). LiClO4 has a heterogeneous nucleation effect on PEO in the blend, irrespective of the presence of PCL. The coordination interaction between PEO and LiClO4 decreases with the increase of the PCL content, so the heterogeneous nucleation ability of LiClO4 on PEO decreases with the increase of the PCL content in the ternary blends. LiClO4 has no heterogeneous nucleation effect on PCL. In the ternary blend, the heterogeneous nucleation effect of PEO on PCL is remarkably promoted with the addition of LiClO4. POM observations show that the miscibility of PEO and PCL improves after the addition of LiClO4, leading to an increase in the interface volume of PEO and PCL phase domains. The increased concentration-fluctuation at the interface promotes the interfacial nucleation of PCL in the ternary blend. The combination of “fluctuation-assisted crystallization” and “interface-assisted crystallization” mechanisms of the interfacial nucleation of PCL in the PEO–PCL binary blend is also suitable for the interfacial nucleation of PCL in the PEO–PCL–LiClO4 ternary blend.