**6. Poly(olefin sulfone)s possessing a photobase generator and base amplifier**

Photoinduced depolymerization of poly(olefin sulfone)s possessing a base‐amplifying moiety in the side chain has been investigated using a film doped with a photobase‐generating compound [19]. Poly(olefin sulfone)s that possess the 9‐fluorenylmethoxycarbonyl (Fmoc) group as a base‐labile N‐protecting group have been synthesized (**Figure 17**). The Fmoc group can undergo amine‐catalyzed thermolysis to an amino group with the evolution of carbon dioxide and dibenzofulvene [20, 21]. Therefore, the number of amino groups increased in the irradiated poly(olefin sulfone) films containing the Fmoc group and doped with PBGs during the subsequent heating step. Even though the irradiation produced few amino groups, their concentration could be amplified by the amine‐catalyzed thermal degradation of the Fmoc group. **Figure 18** shows the decomposition ratio of P4 and P5 plotted as a function of irradiation energy density. The decomposition ratio of copolymer P4 was greater than that of P5. For P4, a decomposition ratio of 98% was obtained at an energy density of 900 mJ/cm<sup>2</sup> . Thus, the presence of a base‐amplifying group in the side‐chain enhanced the amount of base generated in the P4 film.

two types of protons on the main chain undergo only a low extent of decomposition. The number of protons that can be abstracted appears to affect the extent of depolymerization. When many protons existing on a single main chain are abstracted, the yield of monomers

**Figure 16.** Residual ratios of the main‐chains of poly(olefin sulfone)s in films as a function of heating time after irradiation. The concentration of the PBG was 30 wt%. The heating temperature was 120**°**C and the irradiation energy was 3.15 J/cm<sup>2</sup>

.

Photoinduced depolymerization of poly(olefin sulfone)s possessing a base‐amplifying moiety in the side chain has been investigated using a film doped with a photobase‐generating compound [19]. Poly(olefin sulfone)s that possess the 9‐fluorenylmethoxycarbonyl (Fmoc) group as a base‐labile N‐protecting group have been synthesized (**Figure 17**). The Fmoc group can undergo amine‐catalyzed thermolysis to an amino group with the evolution of carbon dioxide and dibenzofulvene [20, 21]. Therefore, the number of amino groups increased in the irradiated poly(olefin sulfone) films containing the Fmoc group and doped with PBGs during the subsequent heating step. Even though the irradiation produced few amino groups, their concentration could be amplified by the amine‐catalyzed thermal degradation of the Fmoc group.

**6. Poly(olefin sulfone)s possessing a photobase generator and base** 

was reduced, as shown in the reaction mechanism in **Figure 4**.

**amplifier**

134 Alkenes

**Figure 17.** Base amplification mechanism and structures of copolymer BA1 and polymer 10.

**Figure 18.** Decomposition ratio of BA1 (○) and polymer 10 (●) as a function of the irradiation energy.
