Figure 2.

Radial patterning during FROMP of dicyclopentadiene. (a) Thermal images revealing circumferential propagation in an open circular mold with an initial temperature of 30 °C: (i) spontaneous heating ahead of the polymerization front at t = 15 s after initiation; (ii, iii) frontal propagation around the circumference following spontaneous heating; and (iv) maximum local temperature during polymerization. (b) Topographic profile of sample shown in a, obtained by optical profilometry; the vertical axis is scaled by 150% for clarity. (c) Surface height measurements of samples prepared with varied initial temperature. Profiles are offset for clarity. (d) Optical image obtained under UV light (365 nm) of the sample in a; 0.25 wt % of 1,1,2,2-tetraphenylethylene was incorporated into the resin prior to frontal polymerization to enhance the fluorescence of resulting samples. (e) Feature wavelength as a function of radial distance from the center of samples prepared with varied initial temperature, determined from optical images of fluorescent samples. (f) Temperature dependence of the wavelength decay constant obtained from the linear fit of wavelength vs radial distance. Reported values and error bars represent the average and standard deviation, respectively (n = 3).