Mechanochemical Synthesis of Functional Materials - Reaction Mechanisms and Possibility of Application to Pharmaceutical Field

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Author Last Name: 
Fumio Saito
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Research Area: 
Size Reduction
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The present annual report composes of three parts; (1) mechanochemical (MC) syntheses of rare earth oxyhalides (ROX, R=La, Sm, Nd, Pr, X=F, Cl, Br) to form functional materials from inorganic systems, (2) MC syntheses of solid state solutions such as LaOCl1-xBrx from mixtures of rare earth oxides (R2O3) and rare earth halides (RX3, X=F, Cl and Br) from the inorganic systems, and (3) MC synthesis of LaOF from an inorganic-organic system (La2O3 and polyvinylidene fluorine (PVDF)). Regarding the first part, the grinding the constituent components (R2O3 and RF3) enables us to form ROF monophase in the product, and the reaction proceeds with an increase in grinding time, and the crystallite size of the product formed is about 15~20nm. As for the second part, the MC reaction proceeds as grinding progresses, forming LaOCl1-xBrx. Unit cell dimensions, a, c and lattice volume of the solutions, evolve linearly with an increase in x in the LaOCl1-xBrx series. Comparing unit cell dimensions of LaOX synthesized by MC reaction to those of LaOX synthesized by solid state reaction at high temperature, there is not any significant difference in the length of c, while a is shortened slightly. This may be attributed to the complex cation layer of (LaO)nn+ with a close relationship to a of the cell dimensions, being affected by the intensive grinding. As for the final part, the reaction through the substitution of F- by O2- results in defluorination of PVDF forming LaOF. This reaction proceeds with an increase in grinding time and is almost completed by about 240min. Mean size of the synthesized LaOF particles is sub-micron order, and the particles look like agglomerates. By prolonged grinding, agglomerated fine particles, consisting of LaOF and resultant organic materials, are transformed to the composites of rupture-like shape and these particles are covered with residual fine particles, progressively. Bonds such as C-O-H and C=C, are formed in the resultant organic phase in the ground mixture. The reaction yield reaches about 98 % at 240min. From these investigations, they have found a new route as well as something that leads perhaps to high possibility of application of this MC reaction to pharmaceutical field.

The future work will be focused on the grinding a mixture of a pharmaceutical raw material like talc with a binder such as cellulose to investigate MC reaction and molecular design between the two materials. In addition, the MC reaction and effect for food materials such as lactose will be investigated. In this study, co-grinding of lactose with cellulose with or without additive such as paracetamol will be made.