Surface hydrophilicity and the inherent washing force are two crucial factors for constructing an underwater self-cleaning surface. Following this self-cleaning mechanism, we fabricated thermosensitive copolymer brushes of N-isopropylacrylamide (NIPAAm) and poly(ethylene glycol) methacrylate (PEGMA) on the polypropylene (PP) surface. Benefiting from the hydrophilic poly(ethylene glycol) (PEG) side chains, the copolymer brushes with the PEGMA content exceeding 5 mol % exhibited good surface hydrophilicity, whenever at temperatures below or above the lower critical solution temperatures (LCST). Hence their underwater oleophobicity was greatly improved with oil contact angles higher than 141° and oil adhesive forces lower than 20 μN. In addition, the sharp volume-phase transition feature was reserved in their copolymer backbones, as proved by the AFM result. Self-cleaning evaluation of the modified surfaces was performed by a simple temperature-change water cleaning method, after which only 0.2 wt % of oil residues remained on the brush surface of P(NIPAAm-5PEGMA) (with 5 mol % of PEGMA contents). The excellent self-cleaning capability is believed to be ascribed to its balanced surface features in hydrophilicity and the sharper volume-phase transition, when a hydrophilic surface can facilitate oil desorption and an intense conformation change of chain stretching and shrinking can offer the strong washing force to assist oil detachment. This study contributes to development of the underwater self-cleaning surface based on a hydrophilic surface with the chain motion.

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Synthesis of a Ti-incorporated zeolite using a simple and economical method has recently become a focus of attention. The direct hydrothermal synthesis of Ti-MWW is most commonly applied; however, it is challenging to perform and exhibits low titanium utilization. An innovative strategy of synthesizing Ti-MWW is proposed in the present study by simply treating the ERB-1 precursor of an MWW-type boron silicate with a H2TiF6/HNO3 solution. This significantly shortens the Ti grafting process from 5 days to only a few hours and reduces the use of the structure-directing agent hexamethyleneimine (HMI); furthermore, no extraframework Ti is observed in the precursor, indicating good atomic economy. Typically, a piperidine (PI)-treated sample Ti-MWW2–1‑PI exhibits a higher conversion (76.6%) than the original Ti-MWW (44.8%) in the epoxidation of 1-hexene. X-ray diffraction (XRD), inductively coupled plasma (ICP), and transmission electron microscopy (TEM) techniques are used to explain in detail the probable mechanism underlying the incorporation of Ti species into the MWW framework. X-ray photoelectron spectroscopy (XPS) is employed to study the coordinate state of the Ti and F species in the samples after treatment with a piperidine solution. This method can be applied to synthesize other kinds of lamellar-structured zeolites with heteroatoms.

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