Bosnar, Sanja; Dutour Sikirić, Maja; Smrečki, Vilko; Bronić, Josip; Šegota, Suzana; Strasser, Vida; Antonić Jelić, Tatjana; Palčić, Ana; Subotić, Boris (2019) Controlled aggregation of the core(amorphous silica)@shell(TPA+-polysilicates) nanoparticles at room temperature by selective removal of TPA+ ions from the nanoparticle shell. Inorganic Chemistry Frontiers, 6 (7). pp. 1639-1653. ISSN 2052-1553
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Abstract
The influence of small inorganic cations (Na+ ions in this case) on the core@shell silica nanoparticles, formed by the room temperature hydrolysis of TEOS in aqueous TPAOH (subsequent addition of NaOH – SA) and NaOH/TPAOH (direct addition of NaOH – DA) solutions was investigated by DLS, AFM, pH measurements, 29Si-NMR and 23Na-NMR. The obtained results showed that the smaller Na+ ions, displace parts of the larger TPA+ ions from the shells of the core@shell primary silica nanoparticles (PNPs), by the exchange process. This causes exposition of TPA-free terminal –OH and –O- groups to the solution and thus, enables the binding of the collided nanoparticles by the Si-O-Si bonds (aggregation). The PNPs in the aggregates, formed above the critical aggregation concentration (CAC) of silicate species are separated by the “bulky” shell (TPA-polysilicate anions) that prevents the close contacts between the nanoparticles cores and thus, their coalescence. When Na+ ions are present during the formation of the nanoparticles, a part of the Na+ ions is incorporated to the nanoparticle core. Remove of the TPA+ ions from the shells of the nanoparticles, formed below the CAC, enables close contacts of the nanoparticles cores and thus, their coalescences inside the aggregates. These findings show that the selective removal of the TPA+ ions from the nanoparticle shell enables the control of the composition and size of the precursor species and thus, represent a good basis for the engineering of nanosized (alumino)silicate microporous and mesoporous materials.
| Item Type: | Article | ||||||||||||
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| Uncontrolled Keywords: | core@shell silica nanoparticles; shell composition; removal of the core-TPA+ ions, controlled aggregation, the influence of NaOH addition | ||||||||||||
| Subjects: | NATURAL SCIENCES > Chemistry | ||||||||||||
| Divisions: | Division of Materials Chemistry Division of Physical Chemistry NMR Center |
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| Depositing User: | Sanja Bosnar | ||||||||||||
| Date Deposited: | 07 Dec 2020 09:40 | ||||||||||||
| URI: | http://fulir.irb.hr/id/eprint/6041 | ||||||||||||
| DOI: | 10.1039/C9QI00200F |
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