**Preface to "Advanced Polymer Nanocomposites"**

Polymer nanocomposites currently attract high levels of industrial interest in various scientific areas in the field of nanomaterials, because they can improve the performance of polymeric matrices and inorganic nanomaterials, such as enhancing light/magnetic behaviors, electrical/thermal conductivity, toughness, stiffness, and mechanical strength. Inorganic quantum dots/nanoparticles, nanorods/nanotubes, and 2D materials (such as graphene-based nanosheets) can be used to decorate the polymer matrix through chemical synthesis or physical blending to improve its performance. Thus, how to fabricate a homogeneous dispersion of fillers in the polymer matrix is a crucial technique in the nanomaterials field. This Special Issue, entitled "Advanced Polymer Nanocomposites", collects high-level original and review papers, focused on scientific discussions and practical applications in the field of functional polymer nanocomposites, including (a) optoelectronic materials (papers 1–6), (b) biomedical materials (papers 7–12), and (c) other functional polymer nanocomposites (papers 13–18). We hope that this Special Issue will promote academic exchanges, and identify and respond to tremendous challenges to disseminate research in this developing field.

> **Ting-Yu Liu and Yu-Wei Cheng** *Editors*
