Table summarizes the hydrostatic pressureratiometric responses (see Figure ). The response factors  (the fluorescence intensity ratios of monomer/excimer) in MeOH, a hydrophilic but organic solvent, are larger than those obtained in aqueous solutions such as H2O and PBS. These different behaviors are likely to be responsible for the conformational changes of the polymer backbones. As shown in the circular dichroism (CD) spectra of Figure , -PLL in MeOH shows two characteristic Cotton peaks relating to -helix and -sheet; in contrast, the CD spectra of the aqueous solutions show only negative maxima (Figure ). These results and previous studies suggest that -PLL adopts a higher-ordered structure in MeOH but a random coil conformation in aqueous solution. Furthermore, the pressure-dependent viscosity of MeOH exhibits a significant change, increasing from 0.544 cP at 0.1 MPa to 0.924 cP at 151 MPa. Conversely, H2O's pressure-dependent viscosity shows little change, ranging from 0.890 cP to 0.889 cP over a pressure range of 0.1 MPa to 100 MPa. Solution viscosity is crucial for the ground-and excited-state dynamics of chromophores. Therefore, we revealed that these two factors are critical in generating larger γ values compared to those obtained in aqueous solutions. Additionally, the CD spectra of ε-PLL in all the studied solvents (as shown in Figure ) exhibited broad positive Cotton effects, indicating an extended conformation. The conformational flexibility of ε-PLLpyrs, which is attributed to the methylene linkers in the repeating unit, results in higher γ values compared to α-PLLpyrs. This suggests that ε-PLLpyrs exhibit better performance as hydrostatic pressure-ratiometric signaling chemosensors. Finally, we investigated the circularly polarized luminescence (CPL) emitted by the pyrene-based polymer chemosensors to explore their potential as chiral emitters. Figure shows that ε-PLLpyrhigh exhibited negative CPL in the excimer regions, with a glum of 2.1 × 10 -3 in MeOH and 3.2 × 10 -3 in H2O, respectively. These values are slightly larger than those observed in the chirally modified pyrenic chromophores (<10 -3 ). This phenomenon can be attributed to the close packing of pyrene chromophores on the chiral PLL backbone. The glum value, as defined in Equation 1, allows us to quantitatively describe the circularly polarized luminescence as: