Tuning TiO$_2$ suspension stability with poly($\alpha$-alkyl carboxylic acids) via side chain length and chain stereochemistry

Berglez, Tilen (author), Kogej, Ksenija (author), Reščič, Jurij (author)

Effects of hydrophobicity and stereochemistry of poly($\alpha$-alkyl carboxylic acids) on the properties of TiO$_2$ suspensions were studied with experimental and in silico methods. Zeta potential measurements show that the addition of the more hydrophilic poly(acrylic acid) (PAA) to TiO$_2$ suspensions shifts the isoelectric point of the nanoparticles towards lower pH the most, followed by poly(methacrylic acid) (PMA) and poly(ethacrylic) acid (PEA). Stereochemistry has a less pronounced effect on suspension stability, except at low pH, where isotactic PMA (iPMA) is not soluble in water. Dynamic light scattering measurements show that the aggregate size of the nanoparticles correlates well with their zeta potential and the aggregates are largest at the isoelectric point of the nanoparticles. Molecular dynamics (MD) and Monte Carlo (MC) computer simulations were used to study the interaction of polyacids with the surface of nanoparticles. MD simulations show that PAA forms the largest amount of hydrogen bonds with TiO$_2$, followed by PMA. PEA forms very low numbers of hydrogen bonds with the nanoparticle surface. MC simulations were used to study the effect of pK$_a$ of COOH groups of polyacids on their adsorption on TiO$_2$. It was found that even small differences in pK$_a$ between the polyacids have a strong effect.

• Language: English
• Keywords: titanium dioxide nanoparticles, poly(alkyl acrylic acid), suspension stability, zeta potential, dynamic light scattering, computer simulations
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Publication status: Published
• Publication version: Version of Record
• Year: 2023
• Number of pages: 11 str.
• Numbering: Vol. 386, art. 122464
• PID: 20.500.12556/RUL-147839
• UDC: 544.778.3
• ISSN on article: 0167-7322
• DOI: 10.1016/j.molliq.2023.122464
• COBISS.SI-ID: 158559491
• Publication date in RUL: 13.07.2023

Record is a part of a journal

• Title: Journal of molecular liquids
• Shortened title: J. mol. liq.
• Publisher: Elsevier
• ISSN: 0167-7322
• COBISS.SI-ID: 15382277

Licences

• License: CC BY-NC 4.0, Creative Commons Attribution-NonCommercial 4.0 International
• Link: http://creativecommons.org/licenses/by-nc/4.0/
• Description: A creative commons license that bans commercial use, but the users don’t have to license their derivative works on the same terms.

Secondary language

• Language: Slovenian
• Keywords: nanodelci titanovega dioksida, poli(alkil arilna kislina), stabilnost suspenzij, zeta potencial, dinamično sipanje svetlobe, računalniške simulacije

Projects

• Funder: ARRS - Slovenian Research Agency
• Project number: P1-0201
• Name: Fizikalna kemija

• Funder: ARRS - Slovenian Research Agency
• Project number: I0-0022
• Name: Mreža raziskovalnih infrastrukturnih centrov Univerze v Ljubljani (MRIC UL)