Affiliation of Author(s):The University of Sydney
Journal:Powder Technology
Key Words:Core-shell Tailored porosity Flower-like microsphere Lactose
Abstract:Flower-like lactose microparticles with tailored porosity on the core and the shell have been synthesized using sugars, such as sucrose, glucose and fructose as templating agents. The proposed mechanism for tailoring the porosityisbasedonthedifferenceinthediffusioncoefficientsoftemplatingsugarscomparedwiththatoflactose as the core material, resulting in the migration of template molecules to the core or the shell of spray-dried particles during the spray-drying process. Focused ion beam (FIB) and scanning electron microscopy (SEM) techniques have been used to investigate the internal structure of the porous lactose particles. It has been found that using sucrose, with a lower diffusion coefficient compared with lactose, resulted in a porous shell upon template removal by ethanol washing, since lactose molecules with higher diffusivity tend to migrate to the core. By contrast, glucose and fructose, with higher diffusion coefficients, led to a porous core due to their tendency to accumulate in the core of the spray-dried particles. Nitrogen physisorption tests showed that the flower-like lactose microspheres have a large surface area of 26–31 m 2 /g and a high pore volume of 0.57– 0.78 cm 3 /g with a pore size distribution predominantly in the micro- and mesoporous range (1.6, 3.8 and 30nm).Theporesizedistributionsoftheseflower-likelactosemicroparticlesshowthatfructose,withthelowest glass-transition temperature (T g ) and consequently the highest crystallization rate during spray drying gave in larger pores, while the sucrose with the highest T g led to smaller pores.
Volume:325
Issue:2018
Page Number:309-315
Translation or Not:no
Links to published journals:https://doi.org/10.1016/j.powtec.2017.11.028