Thin film coatings do much more than spruce up walls. For example, they can be used as pharmaceutical devices in edible films, similar to those to deliver drugs used to fight the opioid epidemic. How these coatings dry can change their properties, which is especially important for films used in drug delivery.
In their paper, "Chemical vs. mechanical microstructure evolution in drying colloid and polymer coatings," the Lehigh researchers looked at how particles rearrange themselves during drying when their interactions are tuned. These particles behaved as a surrogate for the active pharmaceutical ingredient in a drug delivery film.
The researchers found that when particles attract each other, they form a scaffold that buckles and breaks during drying due to the motion of the top interface. "The microstructure for attractive particles at each point during drying is related to the history of the film evolution,"
"In real drug delivery systems, there are many ingredients interacting with each other, always changing concentration and their interactions throughout drying," says Gilchrist. "By reducing this process to the essential ingredients, we can see these interactions as they happen. This may allow new insights into manufacturing of these films."
reference
Thitiporn Kaewpetch et al, Chemical vs. mechanical microstructure evolution in drying colloid and polymer coatings, Scientific Reports (2020). DOI: 10.1038/s41598-020-66875-0