Design, synthesis, and analysis of multi-layered 3D fluorescent polymers derived from anthracene and naphthalene structural units

Abstract

A new class of polymers integrating anthracene and naphthalene was designed and synthesized. The materials adopt compact multilayered architectures that exploit extended π-conjugation and the rigidity of polycyclic aromatic hydrocarbon units. Optimized Suzuki–Miyaura polycondensation afforded polymers characterized by ¹H/¹³C NMR and gel permeation chromatography (GPC). Transmission electron microscopy (TEM) images reveal nanoscale domains with locally lamellar-like contrast features in selected regions, consistent with short-range ordering rather than uniform long-range periodicity across the entire sample. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) indicate decomposition above 250 °C and glass-transition behavior typical of thermally robust aromatic polymers. UV-vis absorption revealed strong π–π* transitions in the UV; steady-state fluorescence displayed pronounced aggregation-induced emission (AIE) in the aggregated state. Dynamic light scattering (DLS) yielded intensity-weighted apparent hydrodynamic diameters from the nano-to sub-micrometer range with sample-dependent mono- or bimodal distributions, consistent with aggregate-rich dispersions that accompany the AIE response. Scanning electron microscopy (SEM) suggests layered surface textures without obvious macroscopic phase separation. Density-functional calculations indicate a layer-dependent shift toward more uniform π-delocalization; monomer sequence and layer number modulated the HOMO–LUMO separation. Overall, these multilayer 3D polymers combine strong luminescence, thermal stability, and tunable structure-photophysics, suggesting potential for optoelectronic and sensing applications.