Fig. 1. A 2D sketch of the simulation model. Two spherical cavities, a small one with radius R_s and a large one with radius R_l, are connected by a small hole with diameter D_h. The polymer is confined in the two cavities.

Fig. 2. The SCO probability P_SCO as a function of R for different N. The radius where P_SCO = 0.5 is defined as the critical radius R_C. The inset shows the phase diagram for the symmetric twin-cavity system. The red line shows the radius of gyration (R_g0) of polymer in free space as a function of N.

Fig. 3. The SCO probability P_SCO as a function of the radius of the small cavity R_s for different R_l (< R_C), where N = 60. The radius where P_SCO = 0.5 is defined as the critical radius R_sC.

Fig. 4. Phase diagram for the asymmetric system, where N = 60. The inset shows the dependence of R_sC on Rl9/4N−3/4 for N = 40, 60, 80, 100, and 120. The solid black line is guide for eyes.

Fig. 5. The relative probabilities of the whole polymer in the small cavity (P_s/P_SCO) and in the large cavity (P_l/P_SCO) in the SCO phase as functions of the radius of the small cavity R_s for different R_l, where N = 60.

Fig. 6. The equilibrium number (m_s) of monomers in the small cavity as a function of R_s for different R_l (< R_C), where N = 60. The inset shows m_s/N as a function of (R_l/R_s)³ for different R_l and N. The solid red line is given by Eq. (12).