Abstract
The development of facile and efficient polymerizations toward functional polymers with unique structures and attractive properties is of great academic and industrial significance. Here we develop a straightforward C–H-activated polyspiroannulation route to in situ generate photoresponsive spiro-polymers with complex structures. The palladium(II)-catalyzed stepwise polyspiroannulations of free naphthols and internal diynes proceed efficiently in dimethylsulfoxide at 120 °C without the constraint of apparent stoichiometric balance in monomers. A series of functional polymers with multisubstituted spiro-segments and absolute molecular weights of up to 39,000 are produced in high yields (up to 99%). The obtained spiro-polymers can be readily fabricated into different well-resolved fluorescent photopatterns with both turn-off and turn-on modes based on their photoinduced fluorescence change. Taking advantage of their photoresponsive refractive index, we successfully apply the polymer thin films in integrated silicon photonics techniques and achieve the permanent modification of resonance wavelengths of microring resonators by UV irradiation.
Highlights
The development of facile and efficient polymerizations toward functional polymers with unique structures and attractive properties is of great academic and industrial significance
The rigid spirocyclic structure may endow the corresponding polymers with unique properties such as high thermal and morphological stability[30]. With these considerations in mind, we explore the possibility of developing this C–H-activated spiroannulation reaction into a straightforward polymerization strategy to in situ generate photoresponsive spiro-polymers from simple monofunctional monomers (Fig. 1b)
The plausible mechanism of the small molecule reaction (Fig. 1a)[28] implied that the stoichiometric balance between the key intermediate E and monomer 2 should be more crucial than the apparent monomer feed ratio for generating polymers with high molecular weights
Summary
The development of facile and efficient polymerizations toward functional polymers with unique structures and attractive properties is of great academic and industrial significance. The obtained spiro-polymers can be readily fabricated into different well-resolved fluorescent photopatterns with both turn-off and turn-on modes based on their photoinduced fluorescence change Taking advantage of their photoresponsive refractive index, we successfully apply the polymer thin films in integrated silicon photonics techniques and achieve the permanent modification of resonance wavelengths of microring resonators by UV irradiation. The rigid spirocyclic structure may endow the corresponding polymers with unique properties such as high thermal and morphological stability[30] With these considerations in mind, we explore the possibility of developing this C–H-activated spiroannulation reaction into a straightforward polymerization strategy to in situ generate photoresponsive spiro-polymers from simple monofunctional monomers (Fig. 1b). The UV-tunable refractive index of the polymer thin films is successfully applied for the permanent modification of resonance wavelengths of microring resonators
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