This study starts with the synthesis of silica hollow spheres (HSs) by utilizing in situ synthesized polystyrene (PS) microspheres as the template for the deposition of a silica (SiO) shell, followed by a slow gasification step in air to remove the PS core. The size of HS and the thickness of the porous SiO shell are tuned by varying the synthesis conditions of the PS latex and those of the sol-gel deposition, respectively. Various HS powder samples are characterized by ultraviolet-visible-near infrared (UV-vis-NIR) spectroscopy to determine their diffuse reflectance. Furthermore, they are used as the filler in an acrylic polymer matrix for the measurement of solar reflectivity on a solar spectrum reflectometer. It turns out that both cavity size and the structure of the SiO shell are influential in the reflection of NIR and UV-vis light, respectively. In addition, this study examines the effect on solar reflectivity of a selected metal oxide with a SiO HS. In conclusion, the cavity size of the HS has a strong impact on the reflectivity to NIR light whereas the shell itself affects the reflection of UV-blue light.

Development of an anti-icing surface on a desired industrial coating patch/object has been the persistent challenge to several industries, such as aviation and wind power. For this aim, performing surface modification to implement the icephobic property on existing commercial coatings is important for practical applications. This work accomplishes an icephobic coating overlying a PPG aerospace polyurethane coating. It manifests a clear capability to delay the formation of frost as well as to reduce the adhesion strength of ice. This icephobic coating is sustained by a unique hydrophobic heterogeneity in the micron-scale of segregation, which is realized through solution casting of a specific copolymer consisting of random rigid and soft segments, namely poly(methyl methacrylate) and poly(lauryl methacrylate-2-hydroxy-3-(1-amino dodecyl)propyl methacrylate), respectively. A wrinkled pattern developed over the coating is observed because of the diverse traits between these two segments. Besides, the OH/NH groups of the soft segment are crosslinked by a diisocyanate monomer upon drying and curing to strengthen the coating. More importantly, integration of a small dose of paraffin wax into the copolymer induces a spread of soft microdomains on the winkled pattern surface. It is hypothesized that these dual heterogeneous assemblies are responsible for the icephobicity since they instigate distinct interactions with condensed water droplets. Lastly, the thermoelectric cooling (Peltier effect) and the adhesion strength of ice on the typical coatings were assessed. This investigation also includes examination on the icephobic durability of coating, which is enhanced when a small amount of polyethylene oligomer is incorporated into the coating.

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This work investigates the effect of atmosphere on pyrolysis of a polymer matrix (precursor) for directing its transformation towards more disordered graphene species and smaller graphitic nanograins. These two structural characteristics are crucial to the generation of nano-channels (NCs) pertinent to nanofiltration (NF). Two measures are explored hereby to conduct the study: varying the pyrolysis atmosphere and implementing highly dispersed nickel atomic clusters (Ni-clusters) in the coating matrix undergoing pyrolysis. A thermally reactive polymer precursor is developed to allow the above two measures to act more effectively. The various pyrolysis atmospheres employed include inert Ar, a reducing H/N gas mixture, and weak oxidizing CO. In the absence of the Ni-clusters, the H/N atmosphere restrains the extent of graphitization through a chain transfer effect of H that ceases the free radical chain propagation, whereas CO, owing to its high critical temperature (T) nature, shows the capability to reduce nanograin sizes. As for the catalytic roles of the embedded Ni-clusters, they vary with the pyrolysis atmosphere applied: offering coke nuclei for the growth of carbonaceous grains in Ar, enhancing gasification of carbon in CO, and repressing the extent of aromatization via hydrogenation in H/N. The carbonaceous membranes (CnMs) obtained under the above pyrolysis conditions are distinguished by the distribution density and structure of NCs evolved, which locate primarily in the boundaries of nanograins. The NF of an aqueous solution of methylene blue (MB, 10 ppmw) is utilized to assess these CnMs to show impacts of the NCs on the separation performance.