We observed similar reversibility in the thermally induced J-to-M transformation for PPC25, PPC20, PPC10 and PPD6 NPs (Figure & Figure ). Nevertheless, the critical annealing temperature (Tc) required to complete the J-to-M transition is higher for the PPCx NPs with shorter PCL chains. Specifically, Tc of PPC25, PPC20, PPC15 and PPC10 NPs increases in the order of 45, 53, 55, 65 o C, respectively. In addition, the J-band of PPC5 NPs remains stable even at 70 o C (Figure ). Similarly, no spectral change was observed for PPD2 NPs and NPs composed of P0/PCL37 physical blend when being heated up to 70 o C (Figure ). Moreover, some extent of H-to-M transformation was observed for PPL10 NPs upon heating at 70 o C (Figure ). Nevertheless, PPL10 NPs remained almost nonfluorescent before and after heating. These results indicate that both the composition and the chain length of the tethering polymers could affect the phase temperature of the NPs, which was further studied by X-ray scattering spectroscopy in the following section.