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In this study, we demonstrate the use of poly (ethylene oxide) (PEO) for in-situ modification of the inner surface of halloysite nanotubes (HNTs) with water molecules as the hydrogen bond forming medium, as well as the nano-confinement of PEO molecular chains within the nanotube. Before testing, the Soxhlet experiment of PEO/HNTs powder is applied in order to remove the physical adsorption of PEO molecules onto the outmost surface of HNTs. The crystal temperature of PEO changes sharply from 36.9 °C of neat PEO to −25 °C of PEO in the PEO/HNTs powder and the decomposed temperature of PEO in the PEO/HNTs powder is about 13.1 °C higher than that of neat PEO, which is mainly owing to the nano-confinement effect of PEO within the HNTs with a diameter of about 10 nm. From thermo-gravimetric (TG) analysis, about 7.71 % by weight of PEO has been chemically bonded to HNTs. The hydrogen bonds among PEO, HNTs, and water molecules are evidenced by FTIR and XPS performances. Meanwhile, the binding energy of Al2p in the innermost surface of HNTs shifts from 74.7 eV in the neat HNTs to 74.5 eV in the PEO/HNTs powder, while that of Si2p on the outmost surface of HNTs keeps almost constant, indicating that the hydrogen bonds only exists inner the nanotube and PEO molecular chains have been trapped in nano-scale within HNTs, which is in accordance with the DSC and TG observation.

Compatibility property, as well as crystalline morphology, of NBR/PEO blends has been investigated by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), X-ray diffraction (XRD), and polarized optical microscopy (POM) thoroughly. There is no apparent shift of nitrile or ether groups in the FTIR spectra of NBR/PEO blends. Based on the calculations from glass transition temperature, the maximum volume fraction of PEO dissolved in NBR phase is about 6.41 % in blend with 5 wt% PEO content (PEO-5), indicating a weak intermolecular interaction in the NBR/PEO blends. From the characteristic absorption bands in the FTIR spectra, XRD and POM graphs, the crystallinity ratio of NBR/PEO blends decreases as the NBR content increases, which is further proved by DSC measurement that the crystallinity ratio and crystal melting temperature of pure PEO are 82.6 %, 69.9 °C, and that of PEO-5 are 16.9 %, 59.5 °C. This illuminates that the weak intermolecular interaction will affect the crystallinity ratio and crystal melting temperature of the NBR/PEO blends.