Synthesis, physicochemical properties and computational study of donor–acceptor polymer for optical limiting application

Abstract

A new donor-acceptor configured π-conjugated polymer P1 with alkoxy pendant groups having cyclic diimide and thiophene core moieties in polymer backbone were efficiently synthesized via polycondensation reaction. The incorporation of cyclic diimide in polymer increased the rigidity and thermal stability of polymer backbone aided by its high T g value. These chromophores assisted in reducing the steric interaction of bulky alkoxy pendants which supported lowering the bandgap. The donor and acceptor moieties along with π spacers were particularly chosen to enhance the π-conjugation length in the polymer thereby increasing its nonlinear optical absorption i.e. two-photon absorption. The various structure-property relationships of the polymer were characterized by UV-Vis absorption, fluorescence emission, cyclic voltammetry, and density functional theory studies. The molecular nonlinear properties were theoretically evaluated through the calculation of polarizabilities and hyperpolarizabilities using time-dependent Hartree-Fock method. The polymer showed enhanced effective two-photon absorption with an absorption coefficient (eff) of 2.031 × 10 −10 m/W obtained from open aperture Z-scan analysis which is in good agreement with theoretical study.

4-[4-(4-Methoxyphenyl)-1,3-butadienyl]-1-methylpyridinium 4-chlorobenzene sulphonate (MBMPCBS) – an efficient nonlinear optical crystal with superior thermal stability

“…45 Further, the lower energy value of the molecule indicates that the molecule can be easily polarized, resulting in enhanced NLO properties. 46…”

Synthesis of Donor–Acceptor Copolymers Derived from Diketopyrrolopyrrole and Fluorene via Eco-Friendly Direct Arylation: Nonlinear Optical Properties, Transient Absorption Spectroscopy, and Theoretical Modeling

“…σ TPA of 621 GM was measured; Figure 12 shows typical Z−scan traces obtained with this polymer. We attribute the nonlinear behavior of these polymeric materials mainly to the increase in electronic conjugation due to the donor-acceptor behavior in the polymeric backbone and the increase in conjugation by the bicyclic dilactam of DPP when coupled with fluorene, as occurs in other D-A polymers [45].…”