An extended duration operation for solid hollow fiber cooling crystallization method

As recently demonstrated by Chen et al. [1], the solid hollow fiber cooling crystallization method to achieve continuous polymer coating/encapsulation of submicrometer particles, has advantages of no problem with high pressure, easy scale-up and production of free-flowing coated particles. There is a concern whether this crystallization method can be applied for an extended duration coating process; it was not investigated in the previous study. Therefore, in order to examine this problem, in this work, the duration of the whole crystallization coating process has been greatly extended from 5 min to 60 min and 120 min. For the purpose of being comparable to the experiments of Chen et al. [1], Eudragit RL 100 was chosen as the coating polymer and Cosmo 55 (550nm silica particles) as the host core for the coating process in an acetone solution. The feeding and cooling process were exactly the same as in the previous research. Scanning electron microscopy and thermogravimetric analysis were employed to characterize the coated samples. The results showed that the solid hollow fiber cooling crystallization method had no problem in extended time running operation; the characterization of products indicated a stable product consistent with uniform and fine spherical shape; the thickness of the coating of the samples tended to be essentially identical as the coating process went through