Hailin Cong

Current status and future developments in preparation and application of colloidal crystals

Colloidal crystals (CCs) are ordered arrays of monodisperse colloidal particles. Because of the presence of a periodic superlattice of colloids and voids, CCs bear many unique structures and fascinating properties which are distinctly different from those of standard crystals with atoms, ions or molecules as repeating subunits. The research on CCs has surprisingly blossomed during recent decades, and many practical materials based on CCs with potential applications in photonic devices, material science and biomedical engineering have been generated. In this review, we give a systematic, balanced and comprehensive summary of the main aspects of CCs related to their preparation and application, and propose perspectives for the future developments of CCs.

Preparation of a highly permeable ordered porous microfiltration membrane of brominated poly(phenylene oxide) on an ice substrate by the breath figure method

A highly permeable ordered porous microfiltration membrane of brominated poly(phenylene oxide) (BPPO) was prepared successfully on an ice substrate using the breath figure method. The effects of polymer concentration and substrate material on the formed porous structures were studied. As the polymer concentration in the casting solution increased, the pore size in the formed membrane decreased. The permeability of the membrane cast on the ice substrate was much higher than that of the membrane cast on a glass substrate, because the formed ice/water interface not only sped up condensation of water droplets, but also helped the water droplets run through the BPPO casting solution under gravity. The ordered porous BPPO membrane with high permeability was not only used for microfiltration, but also used for fabrication of functional microstructures.

Enhanced efficiency of polymer solar cells by incorporated Ag–SiO2 core–shell nanoparticles in the active layer

In this article, we creatively incorporated Ag–SiO2 core–shell nanoparticles (Ag–SiO2-NPs) into photo-/electro-active layers consisting of poly(3-hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) in polymer solar cells (PSCs). By this way, the photovoltaic performances of PSCs have largely been enhanced. The results demonstrate a 13.50% enhancement of short-circuit photocurrent density (Jsc) and a 15.11% enhancement of power conversion efficiency (PCE) as the weight percent of doped Ag–SiO2-NPs is 1.5 wt% in the active layer of corresponding PSCs. We attribute the enhancement to the localized surface plasmon resonance (LSPR) effect of Ag–SiO2-NPs, by which the incident light harvesting is enlarged. Whereas, the incorporated bare Ag nanoparticles (Ag-NPs) in the active layer of PSCs decreases the PCE, which is ascribed to the quenching of excitons at the surface of Ag-NPs and the poor dispersion of Ag-NPs in the active layer. Importantly, this work provides a new approach to enhance the performance of PSCs via the LSPR effect of Ag–SiO2-NPs other than via non-circular nanometals.

Preparation of iridescent colloidal crystal coatings with variable structural colors

Iridescent colloidal crystal coatings with variable structural colors were fabricated by incorporating carbon black nanoparticles (CB-NPs) into the voids of polystyrene (PS) colloidal crystals. The structural color of the colloid crystal coatings was not only greatly enhanced after the composition but also varied with observation angles. By changing the diameter of monodisperse PS colloids in the composites, colloidal crystal coatings with three primary colors for additive or subtractive combination were obtained. After incorporation of the PS/CB-NPs hybrid coatings into polydimethylsiloxane (PDMS) matrix, manmade opal jewelry with variable iridescent colors was made facilely.

Novel covalently coated diazoresin/polyvinyl alcohol capillary column for the analysis of proteins by capillary electrophoresis.

A novel method for the preparation of covalently linked capillary coatings of PVA was demonstrated using photosensitive diazoresin (DR) as coupling agents. Layer‐by‐layer self‐assembly film of DR and PVA based on hydrogen bonding was first fabricated on the inner wall of capillary, then the hydrogen bonding was converted into covalent bonding after treatment with UV light through the unique photochemistry reaction of DR. The covalently bonded coatings suppressed basic protein adsorption on the inner surface of capillary, and thus a baseline separation of lysozyme, cytochrome c and BSA was achieved using CE. Compared with bare capillary or noncovalently bonded DR/PVA coatings, the covalently linked DR/PVA capillary coatings not only improved the CE separation performance for proteins, but also exhibited good stability and repeatability. Due to the replacement of highly toxic and moisture‐sensitive silane coupling agent by DR in the covalent coating preparation, this method may provide a green and easy way to make the covalently coated capillaries for CE.

A novel diazoresin/polyethylene glycol covalent capillary coating for analysis of proteins by capillary electrophoresis

A novel method for the preparation of covalently linked capillary coatings of polyethylene glycol (PEG) was demonstrated using photosensitive diazoresin (DR) as the coupling agent. Layer by layer (LBL) self-assembly film of DR and PEG based on hydrogen bonding was first fabricated on the inner wall of capillary, then the hydrogen bonding was converted into covalent bonding after treatment with UV light through a unique photochemistry reaction of DR. The covalently bonded coatings suppressed protein adsorption on the inner surface of the capillary, and thus a baseline separation of lysozyme (Lys), cytochrome c (Cyt-c), bovine serum albumin (BSA) and ribonuclease A (RNase A) was achieved using capillary electrophoresis (CE). Compared with the bare capillary or non-covalently bonded DR/PEG coatings, the covalently linked DR/PEG capillary coatings not only improved the CE separation performance for proteins, but also exhibited good stability and repeatability. Due to the replacement of highly toxic and moisture sensitive silane coupling agents by DR in the covalent coating preparation, this method may provide a green and easy way to make the covalently coated capillaries for CE.

Fabrication of monodisperse anisotropic silica hollow microspheres using polymeric cave particles as templates

Monodisperse anisotropic poly(styrene-co-divinylbenzene) (PS-DVB) particles with single cavity structures were synthesized using a modified dispersion polymerization method. The effects of DVB adding modes and speeds on the particle morphologies were studied. Using the PS-DVB cave particles as templates, monodisperse anisotropic silica (SiO2) hollow microspheres were fabricated facilely. The obtained anisotropic silica hollow spheres had a potential application in rapid waste removal and detoxification extraction with a very simple procedure.

A novel diazoresin/poly(N‐vinyl aminobutyric acid) covalent capillary coating for the analysis of proteins by capillary electrophoresis

A novel method for the preparation of covalently linked capillary coatings of poly(N-vinyl aminobutyric acid) (PVAA) obtained from hydrolyzed polyvinylpyrrolidone was demonstrated using photosensitive diazoresin (DR) as a coupling agent. A layer-by-layer self-assembled film of DR and PVAA based on ionic bonding was first fabricated on the inner wall of capillary, then ionic bonding was converted into covalent bonding after treatment with UV light through a unique photochemical reaction of DR. The covalently bonded coatings suppressed protein adsorption on the inner surface of the capillary, and thus a baseline separation of lysozyme, cytochrome c, BSA, amyloglucosidase, and myoglobin was achieved using CE. Compared with bare capillary or noncovalently bonded DR/PVAA coatings, the covalently linked DR/PVAA capillary coatings not only improved the CE separation performance for proteins, but also exhibited good stability and repeatability. Due to the replacement of the highly toxic and moisture-sensitive silane coupling agent by DR in the covalent coating preparation, this method may provide a green and easy way to make covalently coated capillaries for CE.

Ionic liquid modified poly(2,6-dimethyl-1,4-phenylene oxide) for CO2 separation

Ionic liquid modified poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) was synthesized by introducing imidazolium-based, pyridinium-based, and ammonium-basd ionic liquid groups to the methyl position of PPO. Membranes were prepared from the different types of ionic liquid modified PPO (IPPO), and the permeability of CO2 and N2 in these membranes was characterized. For having the CO2-philic ionic liquid groups in the structure, the CO2 solubility of the IPPO is better than that of PPO, while the CO2 diffusivity in the IPPO is proportional to glass transition temperatures. The adsorption and desorption of CO2 in the IPPO were also investigated, and the results manifest that the adsorption and desorption of CO2 in IPPO are completely reversible, which makes the polymer promising as solid adsorbent materials for CO2 separation.

Self-assembled and covalently linked capillary coating of diazoresin and cyclodextrin-derived dendrimer for analysis of proteins by capillary electrophoresis

Self-assembled and covalently linked capillary coatings of cyclodextrin-derived (CD) dendrimer were prepared using photosensitive diazoresin (DR) as a coupling agent. Layer by layer (LBL) self-assembled DR/CD-dendrimer coatings based on ionic bonding was fabricated first on the inner surface of capillary, and subsequently converted into covalent bonding after treatment with UV light through a unique photochemistry reaction of DR. Protein adsorption on the inner surface of capillary was suppressed by the DR/CD-dendrimer coating, and thus a baseline separation of lysozyme (Lys), myoglobin (Mb), bovine serum albumin (BSA) and ribonuclease A (RNase A) was achieved using capillary electrophoresis (CE). Compared with the bare capillary, the DR/CD-dendrimer covalently linked capillary coatings showed excellent protein separation performance with good stability and repeatability. Because of the replacement of highly toxic and moisture sensitive silane coupling agent by DR in the covalent coating preparation, this method may provide an environmentally friendly and simple way to prepare the covalently coated capillaries for CE.