Synthesis of multifunctional copolymers of poly(methylphenylsilane) with (R)-N-(1-phenylethyl)methacrylamide, disperse red 1 methacrylate and their optical and photoluminescence properties
We report the synthesis and characterization of multifunctional polysilane copolymers containing chiral and azobenzene chromophore as a pendant group. Multifunctional polymers of poly(methylphenylsilane) (PMPS) with (R)-N-(1-phenylethyl)methacrylamide (R-NPEMAM) and disperse red 1 methacrylate (DR1MA) were synthesized in a quartz tube using UV-technique. The molecular weights of such synthesized copolymers were found to be in the order of 103. The appearance of two glass transition temperatures in DSC indicated that the synthesized copolymers are block copolymers. The electronic absorbance of synthesized polymers was observed at 272 nm (π-π* transition of aromatic ring), 330 nm (σ-σ* transition of Si-Si chain of PMPS) and 475 nm (n-π* with π-π* transition due to azobenzene chromophore of DR1MA unit). The chirality of the synthesized polymer was confirmed through circular dichroism observed at 261 nm. Induced chirality appeared at 330 nm and 470 nm due to the association of the Si-Si chain of PMPS and the presence of azobenzene chromophore of the DR1MA unit respectively. The photoluminescence (PL) properties of the synthesized copolymers (SCDRDM-1B, SCDRDM-2B, and SCDRDM-3B) were observed at 307 nm and 415 nm when excited at 275 nm. The λem was also observed at 415 nm when excited by 325 nm. The multi-emission spectra appeared at 500 nm, 550 and 590 nm are presumed to be due to exciton coupling between azobenzene chromophore of DR1MA, and Si-Si σ-conjugation in association with the aromatic ring of PMPS and chiral unit R-NPEMAM block.
