Preparation of sulfur hydrophobized plasmonic photocatalyst towards durable superhydrophobic coating material

Abstract

The widely used photocatalytic self-cleaning coating materials are often made of polymers and polymer based composites, where the photocatalyst immobilization occurs with macromolecules. However, these organic polymers are often unstable under exposure to UV irradiation and easily degraded by reactive radicals produced in the photocatalytic reaction. In order to solve this problem, in this paper, we present the facile preparation of a multifunctional coating with dual superhydrophobic and photocatalytic properties, where the fixation and the hydrophobization of the plasmonic Ag-TiO 2 photocatalyst particles with visible light activity was performed with non-water soluble sulfur, which is a cheap and easily available material. The resulted novel nanocomposite with rough and nano-tructured surface roughness (1.25-2.45 nm determined by small-angle X-ray scattering) has sufficient low surface energy (3.3 mJ/m 2) for superhydrophobic ( = 151.1 •) properties. Moreover, in contrast of the organic and expensive fluoropolymer based composites, this non-wetting nature was durable, because the measured  was higher than 150 • during the long-term LED (max = 405 nm) light irradiation.

Chitosan–gelatin enhanced antibacterial and biological properties of PLA and PGA braided threads for juvenile pseudomyopia treatment

“…The main advantages of these biomass materials are cheap, rich resources and easy availability. 21 Due to the recognition of the issues of natural and synthetic ACEM materials, a series of strategies had been proposed to enhance their surface functional properties. [22][23][24] Hongsriphan and Sanga 25 applied chitosan solutions with different concentrations (0.25, 0.50, 1.00, and 2.00% w/v) to deposit an antibacterial layer on the surface of PLA; the results showed that the chitosan coating had enhanced the water vapor transmission rate, mechanical properties, and antibacterial activity against Staphylococcus aureus and Escherichia coli.…”

Visible light-photoreactive composite surfaces with thermoresponsive wetting and photocatalytic properties

“…To enhance the thermoresponsive layers with visible light photocatalytic activity, plasmonic Ag-TiO 2 photocatalyst nanoparticles were incorporated into the PDSM/PNIPAAm copolymer matrices. As it is detailed in our previous publications, the catalyst and its composites exhibit visible light photoactivity (λ abs,max ~ 450 nm; E g = 3.08 eV band gap energy) with excellent photodegradation-efficiency against organic pollutants, and antimicrobial activity in many scenarios [33,34,[44][45][46]. By dispersing 15 wt% Ag-TiO 2 photocatalyst nanoparticles in the doctor blade-casted and spray-coated layers of PDMS-co-INI matrix, Ag-TiO 2 /PDMS-co-INI composite layers were formed.…”

“…Raman microscopy measurements were performed with a Thermo Scientific DXR Raman microscope (Thermo Fisher Scientific; Waltham, MA, USA). A laser-light of 780 nm wavelength was used, and its Mérai et al -Express Polymer Letters Vol.16, No.1 (2022) [34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51] maximum power was 24 mW. The microscopic lenses used for measurements were magnified 50×, and the aperture was 25 µm.…”

“…As the rate of heterogeneous photocatalytic reactions at the S/L-interface could be dependent on many factors, including the wettability of the solid surface by the liquid medium [46], the above-presented thermoresponsive wetting characteristics could -nonsurprisingly -influence the photocatalytic performance of spray-coated Ag-TiO 2 /PDMS-gr-PNIPAAm films, as well, which was proved by MB-photodegradation tests below (25 °C) and above (50 °C) the LCST of surface PNIPAAm. The upper limit of the photocatalyst-content of the examined composite layers (d = 19 mg/cm 2 ) was set to 15 wt% due to the extreme decline in mechanical durability and adhesive properties we experienced in the case of films with higher Ag-TiO 2amounts.…”

“…This proposed mechanism is depicted in Figure 8. However, it is also important to note that in similar photoreactive coatings, the surface of photocatalyst particles is mostly covered in the matrix material [46] (also depicted in Figure 8), which may photodegrade over time, resulting in a gradually increasing photodegradation efficiency towards the model pollutants as the photocatalyst particles become more exposed to incident light. To support the obtained contact angle and photodegradation efficiency data, the surface free energy values (γ tot ) of the examined photoreactive composites were also determined.…”