Structure evolution during phase separation in spin-coated ethylcellulose/hydroxypropylcellulose films

Abstract

Porous phase-separated films made of ethylcellulose (EC) and hydroxypropylcellulose (HPC) for controlled drug release were made using spin-coating. The method optimization gave good control over the film thickness and the length scale.

Structure formation and coarsening kinetics of phase-separated spin-coated ethylcellulose/hydroxypropylcellulose films

“…In further a further experiment, 64 the cross section of the film was monitored, and the shrinkage of the film was investigated. By identifying the upper and lower interfaces of the film it was possible to estimate the thickness of the film during solvent evaporation.…”

“…Fourier image analysis is a very pertinent tool for phase separation analysis. [54][55][56][57] The exact method applied to the EC/HPC phase separated structure is described in detail in Carmona et al 4 and used in this article to calculate the characteristic length scales of the bicontinuous structures.…”

“…3d-f are showing the different steps. First, noise reduction and smoothing were performed as in Carmona et al 4 Second, the image was binarized using thresholding and the features on the edges of the image were removed, see Fig. 3e.…”

“…It is a widely used technique for making uniform polymer films with high reproducibility of the obtained film structure. In a previous work, 4 spin-coating was utilized to form thin EC/HPC films, and the influence of the spin-coating parameters on the final dried structure was determined. Fig.…”

“…Phase separation in EC/HPC systems has been studied previously and it was found that in most cases, the system phase-separates through spinodal decomposition. 4 In addition, the 3D structure and porosity, pore size distribution, pore shape and connectivity of EC/HPC films have been determined using Focused Ion Beam Scanning Electron Microscopy (FIB-SEM) and advanced image analysis: [48][49][50][51] FIB-SEM allowed identification of central features of the porous network by quantification of channels where pore paths coincide. It was found that the interconnectivity and porosity increase with increasing amount of HPC.…”