Next, we attempted to control the formation of supramolecular polymers using hydrostatic pressure. To date, we have revealed the hydrostatic-pressure-induced spectral responses of functional molecules, supramolecules, polymers, and biomacromolecules. This hydrostatic pressure-control concept can be accounted for using Eq. 1, in which the volume change term (V°) related to solvation/desolvation and conformational changes, plays a decisive role in modulating dynamic equilibrium systems. Thus, this approach was applied in the present sumanene polymerization case. The concentration-dependent UV spectra in 7:3 (v/v) MCH-CH2Cl2 were measured at four pressures ranging from 100 to 250 MPa. As shown in Figures , no new absorption bands appeared upon hydrostatic pressurization. However, decreases in the extinction coefficients were observed with increasing concentrations, as was the case at atmospheric pressure (0.1 MPa). The V° value was then calculated from each K (Tables ) upon supramolecular polymerization at the four measured pressures, according to Eq. 2.