Structural Water Content in Pigment-Grade TiO2 Particles Coated with Al2O3 and SiO2, and Their Effect on Polypropylene Photodegradation
Source abstract
Abstract
The influence of structural water in alumina (Al2O3) and silica (SiO2) coated titanium dioxide (TiO2) pigments on the photodegradation behavior of polypropylene (PP) composites was investigated. Four commercial rutile TiO2 pigments with varying surface inorganic coatings were incorporated into PP plaques and subjected to accelerated UV weathering to simulate outdoor exposure. Photodegradation was assessed through gloss retention measurements, the carbonyl index (CI), and stress at break retention, while pigment morphology and composition were analyzed using transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS). Surface charge and water content were determined through the zeta potential (ζ), Karl Fischer titration, thermogravimetric analysis (TGA), and Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS). The results showed that low-alumina coating alone led to the lowest photodegradation resistance, the highest CI, and the lowest stress at break retention. In contrast, increasing alumina content enhanced photostability, reaching its maximum for combined alumina–silica coatings, which mitigated electron–hole pair migration. PP composites with high alumina–silica-coated TiO2 exhibited higher gloss retention (36%) compared to low-alumina samples (21%). Furthermore, statistical analysis using ANOVA revealed significant differences in coating content and ζ potential among the pigment grades. These findings provide novel insights into oxide-water interactions and the impact of structural water on the photodegradation of polymer composites.
Source: crossref · Quality: baseline
Research context
OpenAlex topics: TiO2 Photocatalysis and Solar Cells · Pigment Synthesis and Properties · Photopolymerization techniques and applications
SciVX discovery tags are terminology-based. OpenAlex topics are source-provided classifications.
Affiliations
Doctorado Institucional en Ingeniería y Ciencia de Materiales (DICIM), Universidad Autónoma de San Luis Potosí, San Luis Potosí 78210, Mexico
Tecnología Sustentable Greennova S.A. de C.V., San Luis Potosí 78395, Mexico
Departamento de Física, Universidad Autónoma Metropolitana, Ciudad de Mexico 09310, Mexico
Instituto de Física, Ing. Luís Rivera Terrazas, Benemérita Universidad Autónoma de Puebla, Puebla 72570, Mexico
Instituto de Física, Universidad Autónoma de San Luis Potosí (IF-UASLP), San Luis Potosí 78000, Mexico
Funding
Greennova
References (42)
Show source-provided references
1. Synthesis and Application of Titanium Dioxide Photocatalysis for Energy, Decontamination and Viral Disinfection: A Review10.1007/s10311-022-01503-z ↗
2. Polymer Nanocomposites Based on TiO2 as a Reinforcing Agent: An Overview10.1002/adem.202200844 ↗
3. Samoylov, A.M., and Popov, V.N. (2021). Titanium Dioxide (TiO₂) and Its Applications, Elsevier.
4. Flow-Induced Alignment of Titanium Dioxide Nanorods in Polyolefin Tubes for Use in Catheters10.1016/j.matdes.2023.112277 ↗
5. Wu, X. (2022). Applications of Titanium Dioxide Materials. Titanium Dioxide—Advances and Applications, IntechOpen.10.5772/intechopen.99255 ↗
6. A Review on the Synthesis of the Various Types of Anatase TiO2 Facets and Their Applications for Photocatalysis10.1016/j.cej.2019.123384 ↗
7. Challenges and New Opportunities on Barrier Performance of Biodegradable Polymers for Sustainable Packaging10.1016/j.progpolymsci.2021.101395 ↗
8. Chemical Modification of Titanium Dioxide Nanoparticles with Dicarboxylic Acids to Mediate the UV Degradation in Polyethylene Films10.1007/s00289-019-03066-6 ↗
9. Titanium Dioxide Nanoparticle-Decorated Polymer Microcapsules Enclosing Phase Change Material for Thermal Energy Storage and Photocatalysis10.1021/acsapm.0c01410 ↗
10. Oxidation and Fragmentation of Plastics in a Changing Environment; from UV-Radiation to Biological Degradation10.1016/j.scitotenv.2022.158022 ↗
11. Wavelength Effect on Polymer Photooxidation under LED Weathering Conditions10.1016/j.polymdegradstab.2022.110021 ↗
12. Alavian Petroody, S.S., Hashemi, S.H., Škrlep, L., Mušič, B., van Gestel, C.A.M., and Sever Škapin, A. (2023). UV Light Causes Structural Changes in Microplastics Exposed in Bio-Solids. Polymers, 15.10.3390/polym15214322 ↗
13. Vital-Grappin, A.D., Ariza-Tarazona, M.C., Luna-Hernández, V.M., Villarreal-Chiu, J.F., Hernández-López, J.M., Siligardi, C., and Cedillo-González, E.I. (2021). The Role of the Reactive Species Involved in the Photocatalytic Degradation of HDPE Microplastics Using C,N-TiO2 Powders. Polymers, 13.10.3390/polym13070999 ↗
14. Photodegradation of Polyethylene Debris in Water by Sulfur-Doped TiO2: System Optimization, Degradation Mechanism, and Reusability10.1007/s11356-023-31460-1 ↗
15. New Insights into the Mechanism of Photodegradation of Chitosan10.1016/j.carbpol.2021.117715 ↗
16. Chemisorbed and Physisorbed Water at the TiO2/Water Interface10.1021/acs.jpclett.7b00564 ↗
17. Role of Adsorbed Water on Charge Carrier Dynamics in Photoexcited TiO210.1021/acs.jpcc.7b00472 ↗
18. Thermal Stability and Ageing Properties of PP–PE Film Modulated by Nano-Silica Particles: Comparison between Dry and Moist Particles10.1007/s00289-020-03258-5 ↗
19. Controlling TiO2 Photocatalytic Behaviour via Perhydropolysilazane-Derived SiO 2 Ultrathin Shell10.1039/D4NR03566F ↗
20. Guo, J., Van Bui, H., Valdesueiro, D., Yuan, S., Liang, B., and Van Ommen, J. (2018). Suppressing the Photocatalytic Activity of TiO2 Nanoparticles by Extremely Thin Al2O3 Films Grown by Gas-Phase Deposition at Ambient Conditions. Nanomaterials, 8.10.3390/nano8020061 ↗
21. (2025, May 22). Ti-PureTM TiO2 by Chemours Titanium Dioxide Solutions for Plastics. Available online: https://www.tipure.com/en/applications/plastics.
22. (2025, May 22). Titanium Dioxide—Venator. Available online: https://www.venatorcorp.com/products-and-applications/products/titanium-dioxide.
23. (2025, May 22). Ti-PureTM Solutions for Coatings: Applications. Available online: https://www.tipure.com/en/applications/coatings.
24. Campanale, C., Savino, I., Massarelli, C., and Uricchio, V.F. (2023). Fourier Transform Infrared Spectroscopy to Assess the Degree of Alteration of Artificially Aged and Environmentally Weathered Microplastics. Polymers, 15.10.3390/polym15040911 ↗
25. Zhou, Q., Liu, X., Lu, Y., Dao, X., and Qiu, L. (2022). Accelerated Laboratory Weathering of Polypropylene/Poly (Lactic Acid) Blends. Polymers, 15.10.3390/polym15010017 ↗
26. Surface-Modified TiO2 @SiO2 Nanocomposites for Enhanced Dispersibility and Optical Performance to Apply in the Printing Process as a Pigment10.1021/acsomega.3c02679 ↗
27. LLDPE/TiO2 Composites with High UV Aging Resistance and Mechanical Properties by Controlling the Alumina Coating on TiO210.1002/pc.29045 ↗
28. Development of New LSD Formula When Numbers of Observations Are Unequal10.4236/ojs.2018.82016 ↗
29. Mui, J., Ngo, J., and Kim, B. (2016). Aggregation and Colloidal Stability of Commercially Available Al2O3 Nanoparticles in Aqueous Environments. Nanomaterials, 6.10.3390/nano6050090 ↗
30. Ceballos-Chuc, M.C., Ramos-Castillo, C.M., Rodríguez-Pérez, M., Ruiz-Gómez, M.Á., Rodríguez-Gattorno, G., and Villanueva-Cab, J. (2022). Synergistic Correlation in the Colloidal Properties of TiO2 Nanoparticles and Its Impact on the Photocatalytic Activity. Inorganics, 10.10.3390/inorganics10090125 ↗
31. Facet-Engineered TiO2 Nanomaterials Reveal the Role of Water–Oxide Interactions in Surface Protonic Conduction10.1039/D1TA06075A ↗
32. Surface Chemistry of Metal Oxide Nanoparticles: NMR and TGA Quantification10.1007/s00216-022-03906-x ↗
33. Li, W., Franco, D.C., Yang, M.S., Zhu, X., Zhang, H., Shao, Y., Zhang, H., and Zhu, J. (2019). Comparative Study of the Performances of Al(OH)3 and BaSO4 in Ultrafine Powder Coatings. Processes, 7.10.3390/pr7050316 ↗
34. DRIFTS Study of Surface of γ-Alumina and Its Dehydroxylation10.1021/jp711901s ↗
35. The Mechanism of the Dehydration of Crystalline Aluminum Hydroxide and of the Adsorption of Water by the Resulting Alumina10.1021/j150219a003 ↗
36. Thermally Activated Al(OH)3 Part II—Effect of Different Thermal Treatments10.3390/ceramics4040040 ↗
37. Zheng, X., Yuan, F., Ma, A., and Tian, S. (2024). Experimental Study on Microwave Drying Aluminum Hydroxide. Coatings, 14.10.3390/coatings14060687 ↗
38. Kinetics Study of Hydration Reaction between Aluminum Powder and Water Based on an Improved Multi-Stage Shrinking Core Model10.1016/j.ijhydene.2021.07.191 ↗
39. The Influence of Surface Alumina and Silica on the Photocatalytic Degradation of Organic Pollutants10.3390/catal3010338 ↗
40. Hydrous Alumina/Silica Double-Layer Surface Coating of TiO2 Pigment10.1016/j.colsurfa.2012.05.010 ↗
41. Effects of Silica Coating on Photocatalytic Reactions of Anatase Titanium Dioxide Studied by Quantitative Detection of Reactive Oxygen Species10.1016/j.apcatb.2012.09.034 ↗
42. Navidpour, A.H., Abbasi, S., Li, D., Mojiri, A., and Zhou, J.L. (2023). Investigation of Advanced Oxidation Process in the Presence of TiO2 Semiconductor as Photocatalyst: Property, Principle, Kinetic Analysis, and Photocatalytic Activity. Catalysts, 13.10.3390/catal13020232 ↗