## 3 Results and Discussions
To investigate the CD enhancement, we compared the effect of annealing on the UV-visible absorption and CD spectra of pure PFBT and PFBT/SU-8 photopatterned films. The UV-visible absorption spectra of the PFBT/SU-8 samples were similar to that of the pure PFBT film. However, the patterned PFBT/SU-8 showed much larger CD than the pure PFBT film (Figure 4). After annealing, the maximum CD signal from the patterned film was 30 times that of the pure chiral PFBT film of the same optical absorbance (Figure 4B). We attribute this to the local changes in the PFBT configuration. However, the CD of the cleanly patterned PFBT/SU-8 was lower than that of a PFBT/SU-8 sample patterned as described in our previous work (Figure 4B). The peak value of CD (\(-\)789 mdeg) was 42% of the corresponding peak value for the pattern with residual film (\(-\)1890 mdeg). In the measurement of the CD spectrum, linear dichroism and linear birefringence frequently make a huge artifact especially in the polymer film or crystal sample [27]. To verify the measured CD spectrum, we remeasured the PFBT/SU-8 cleanly patterned film and annealed PFBT/SU-8 cleanly patterned film by CD spectrometer with different orientations. As shown in Figure 5, remeasured values were very similar compared to the original values. Figure 3: SEM images of patterned chiral polymer. Black bar scale = 100 \(\upmu\)m. (**A**) Ring shape, (**B**) spiral shape, (**C**) spheroid shape, (**D**) inductor shape. While graph (4) shows -789 mdeg, the remeasured value shows -825 mdeg, which is slightly increased as shown, in graph (2), and the results show that the measured CD spectrum of PFBT/SU-8 cleanly patterned films were obtained accurately. All these measured spectra show that the residual film in the nominally unpolymerized regions makes a substantial contribution to the  
Figure 4: **(A)** UV absorption and (B) circular dichroism (CD) of chiral polymer films: (A-1) annealed pure PFBT/SU-8 patterned film with residual PFBT/SU-8, processed as in our previous work [26], (A-3) annealed PFBT/SU-8 film patterned cleanly, using optimized conditions, (**B**) (B-1) annealed pure PFBT film, (B-2) PFBT/SU-8 patterned film with residual PFBT/SU-8, (B-3) annealed PFBT/SU-8 patterned film with residual PFBT/SU-8, (B-4) PFBT/SU-8 cleanly patterned film, (B-5) annealed PFBT/SU-8 cleanly patterned film. All patterned samples were 1:40 (PFBT-SU-8) mass ratio films spin-coated from 30% solid content SU-8 solution. Figure 5: CD of chiral polymer films: (1) remeasured PFBT/SU-8 cleanly patterned film, (2) remeasured annealed PFBT/SU-8 cleanly patterned film, (3) PFBT/SU-8 cleanly patterned film, (4) annealed PFBT/SU-8 cleanly patterned film. CD. We suggest that the aggregation state of PFBT can change more freely during annealing in the thinner, residual film, leading to increased helical organization. As a result, the areas with residual film could have even higher chirality than the thicker areas. Additional ordering could be introduced by the interfaces. Nonetheless, the cleanly patterned film still shows extraordinarily high CD. Moreover, the cleanly patterned films have a clear difference in chirality between the exposed and unexposed areas. This difference in chiro-optic properties between regions may be more important than the absolute value of the chirality parameter in applications.