Ftir carry 600

The particle size and morphology of shell nacre powder were studied by SEM. Shell nacre powder was mixed with potassium bromide at a ratio of 1:400, and the FTIR spectrum was recorded from 400 to 3750 cm⁻¹ at a resolution of 4 cm⁻¹ (FTIR Carry 600, Agilent technologies, Bangalore, India). The Raman spectrum of shell nacre powder was recorded using confocal Raman microscopy (alpha 300RA, Witec, Ulm, Germany) with a 532 nm laser. The XRD spectrum was measured (Bruker, D8 Advance, Germany) in the 2θ range of 10–70° with CuKά radiation in the incremental step of 5°, and peaks were identified using the JCPDS (Joint Committee on Powder Diffraction Standards) database. TGA analysis of shell nacre powder was carried out using SDT-2960, TA Instruments, heating the powder from room temperature to 1000 °C (heating rate of 10 °C/min) in a nitrogen atmosphere. Trace elements such as Cu, Fe, Mg, Mn, Zn, Cd, Pb, Hg, and Se were estimated using optical emission spectroscopy with inductively coupled plasma (OES-ICP) (PerkinElmer, Hopkinton, MA, USA).

The refractive index of the resin was observed using an Abbey refractometer (ATAGO 3T, Tokyo, Japan). The FTIR spectra of the synthesized resins were measured using FTIR Carry 600 (Agilent Technologies). The spectra were obtained from 600 to 4000 cm⁻¹ with a resolution of 4 cm⁻¹. A thick layer of resin was applied on a glass slide, and the Raman spectrum was recorded using confocal Raman microscopy. Thermal stability of the resins (SNLSM1, SNLSM2) was evaluated by heating from room temperature to 1000 °C at the heating rate of 10 °C/min, in a nitrogen atmosphere. The SNLSM2 resin (in methanol) was drop-casted onto formvar-coated 200 mesh copper grids (EM sciences, Hatfield, PA, USA) and allowed to dry overnight. The grid was then observed by using a transmission electron microscope (TEM) (Hitachi H-7650 Tokyo, Japan) at an accelerated voltage of 80 kV. All graphs were drawn using Origin Pro (version 8.5).