Fig. 3.

Pore diameter and geometry can be controlled with embossing parameters. (A) Pore diameter decreased as embossing dwell time increased. Dwell times between 10–15 min did not change pore diameters significantly from nominal pore size. *, p < 0.01 compared to 0 min dwell time, †p < 0.001, compared to 20 min dwell time. (B) For larger nominal pore diameters and a 20 min dwell time, embossing decreased pore size slightly over all topographical feature geometries, although the fractional change between the control and embossed pore diameters decreased as nominal pore diameter increased. *, p < 0.05 compared to control. (C) SEM images above illustrate the differences in elongation of 3–12 μm pores embossed with 10Grat topography. Smaller nominal pore sizes were more elongated than larger nominal pore sizes. Control membranes, regardless of pore size, have elongated pore morphology, with 3 μm pores having an elongation of almost 35%. Hot embossing elongated the pores significantly, although this was not consistent for all patterns and nominal pore sizes. In general, smaller pore sizes elongated due to embossing more often than larger pore sizes. *p < 0.02 compared to control pore size; †, p < 0.05 compared to control pore size. All samples represented in (B) and (C) were embossed for 20 min under 820 kPa of pressure at 150 °C. Measured pore diameters were derived from the calculated pore area using image analysis software. Data is presented as mean ± standard deviation.