weaker and broader.
Heating at 900 C causes the MPS reflections to disappear
completely with the loss of the ordered MPS mesostructure.
The changes in the XRD patterns occur at lower
heating temperatures in the composite S/T than in S/M.
Since pure MPS(M) retains its mesostructure after heating
at 900 C [10], the presence of the ST-01 particles
degrades the thermal stability of the MPS. The XRD
reflections corresponding to the TiO2 phases (Fig. 9b)
show a difference between the composites and ST-01. The
anatase reflection of ST-01 becomes noticeably sharper on
heating and is transformed to rutile at 800 C. By contrast,
the two composites showed only gradual sharpening of the
anatase reflection, and no rutile formation on heating to
900 C. Composite formation with MPS suppresses the
anatase–rutile transformation by preventing aggregation of
the TiO2 particles, retarding their grain growth [29], e.g.
the crystallite size of anatase in ST-01 is 34 nm but only
12 nm in S/M and 11 nm in S/T.