Effects of ageing conditions and block copolymer concentration on the stability and micellization of P123-Ti4+ sols prepared by the templating method

• Published in: Research on chemical intermediates Vol. 36; no. 8; pp. 897 - 923
• Main Authors: Samiee, L., Beitollahi, A., Bahmani, M., Akbarnejad, M. M., Vinu, A.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.11.2010
• Subjects: Catalysis; Chemistry; Chemistry and Materials Science; Inorganic Chemistry; Physical Chemistry; P123 copolymer template; Ordered mesoporous TiO; Sol ageing conditions
• ISSN: 0922-6168; 1568-5675
• DOI: 10.1007/s11164-010-0204-8

In the work reported here we studied, for the first time, the effects of ageing conditions (temperature and time) on the stability and micellization of two sets of sols with different P123 block copolymer (BC) concentrations by use of dynamic light scattering (DLS). Further, for a comparative study the aggregation/clustering behavior of pure P123 in IPA solution was also examined by DLS, and 1 H NMR, and Raman spectroscopy at room temperature. Different ageing regimes applied to the samples prepared included: (i) in-situ ageing of the sols in the sealed capillary cell of the DLS system at room temperature for 0, 1, 2, 3, 4, 5, 6, and 19 h, (ii) ageing of the sols in a Teflon-lined sealed vessel at 50, 55, 60, and 65 °C for 30 min, and (iii) isothermal ageing of the synthesized sols at 50 °C for 1, 4, 8, and 14 days. On the basis of the results obtained it is shown that both ageing time and temperature have remarkable effects on the clustering and aggregation of unimer/micelles formed in the sol system studied. Further, quantitative analysis of interparticle potential energy carried out for the prepared sol at low concentration confirmed that steric interactions play the major role among the other contributing sources of energy. This is mainly related to the presence of BC and the complex polymer structure formed by acetyl acetone (ACAC). Moreover, on the basis of the calculated stability ratio for this sol, we believe that reaction-limited cluster aggregation (RLCA) is possibly the major governing mechanism. Finally, kinetic and dynamic aspects of the micellar aggregates formed are also discussed in this paper.