In situ synthesis of titanium phosphonate by a non-hydrolytic sol-gel route within a viscous polymer medium

Different titanium phosphonates were in situ synthesized within a polymer matrix via non-hydrolytic sol-gel reactions to elaborate nanocomposites with 10 wt% filler content. Titanium tetraacetate was used as titanium dioxide precursor. Three diethyl phosphonates with different organic groups were selected depending on the polymer medium, polypropylene or polystyrene respectively. Polymer/titanium phosphonate nanocomposites obtained were characterized by TGA, FTIR and 31 P solid-state NMR spectroscopies, XRD and electron microscopy. For the polypropylene-based composite, the titanium phosphonate fillers synthesized from diethyl octylphosphonate (DEOP) exhibited an average size of 900 nm and appeared well-dispersed. XRD experiments demonstrated the absence of signal corresponding to crystalline layered titanium phosphonate. With polystyrene, two diethyl phosphonate molecules containing aromatic groups were used to obtain composites. The diethyl benzylphosphonate (DEBP) led to the formation of agglomerates of about 490 nm whereas diethyl phenylphosphonate (DEPP) led to the formation of bigger fillers. However, both systems led to the appearance of fillers with a platelet-like morphology. These results confirmed the significant impact of the solvent (here viscous polymer medium) on the growth and morphology of the created objects. Graphical Abstract