Qijian Niu

A novel high-refractive index episulfide-thiol polymer for nanoimprinting optical elements

A novel optical polymer with a high refractive index (n = 1.707 at 590 nm) was developed consisting of episulfide and thiol bifunctional monomers. The episulfide derivative of 9,9-bis(4-glycidyloxyphenyl)fluorene, synthesized by the reaction of an epoxide and inorganic thiocyanate, reacts by a ring-opening polymerization with 4,4-thiodibenzenethiol to produce the optical polymer with high transparency over the visible region of the spectrum and thermally stable up to 290 °C. The developed episulfide-thiol optical polymer can be thermally nanoimprinted at 160 °C with nanoscale size resolution. Different nanostructures including sub-micron and nanoscale size gratings, two-dimensional photonic crystals, and plano-convex semispherical microlenses were successfully nanoimprinted with excellent pattern fidelity and low defectivity. These results exhibit the episulfide-thiol optical polymer as a potential candidate for applications in optical and optoelectronic devices.

Facile fabrication of PAN/PDMS core-shell nanofibers from synchronous photopolymerization

Different from the traditional method for fabricating core-shell structure nanofiber, the PAN/PDMS nanofibers with core-shell structure (PAN as the core layer and PDMS as the shell layer) have been illustrated, which combines with the synchronous photopolymerization during emulsion electrospinning process. The morphology and structure of as-fabricated PAN/PDMS nanofibers are characterized by SEM and TEM. The composition of PAN/PDMS nanofibers is characterized by FTIR, XPS, TG, and DTG, successfully. The photopolymerization process is characterized by UV-vis spectroscopy indirectly. The WCA tests show that it has good hydrophobicity, which makes it possible as functional material. Meanwhile, the most important thing is that the method provides a flexible design strategy of core-shell structure nanofibers.