Vectorial spin-orbital Hall effect of light upon tight focusing and its experimental observation in azopolymer films

Hall effect of light is a result of symmetry breaking in spin and/or orbital angular momentum(OAM)possessing optical system and is caused by e.g.refractive index gradient/interface between media or focusing of a spatially asymmetrical beam,similar to the electric field breaking the symmetry in spin Hall effect for electrons.The angular momentum(AM)conservation law in the ensuing asymmetric system dictates redistribution of spin and orbital angular momentum,and is manifested in spin-orbit,orbit-orbit,and orbit-spin conversions and reorganization,i.e.spin-orbit and orbit-orbit interaction.This AM restructuring in turn requires shifts of the barycenter of the electric field of light.In the present study we show,both analytically and by numerical simulation,how different electric field components are displaced upon tight focusing of an asymmetric light beam having OAM and spin.The relation between field components shifts and the AM components shifts/redistribution is presented too.Moreover,we experimentally demonstrate,for the first time,to the best of our knowledge,the spin-orbit Hall effect of light upon tight focusing in free space.This is achieved using azopolymers as a media detecting longitudinal or z component of the electrical field of light.These findings elucidate the Hall effect of light and may broaden the spectrum of its applications.

Directional Photo-manipulation of Self-assembly Patterned Microstructures

Highly intricate surface architectures derived from patterned polymer microstructures have received increasing concern in recent years.Directional photo-manipulation(DPM)of azopolymers is one of the effective strategies to tune the patterned polymer microstructures through directional mass migration(DMM)upon polarized light illumination.In this feature article,we emphasize the latest advances of DPM on azopatterns created by self-assembly.The mechanism of DMM,the photo-manipulation performance,and functions of manipulated patterns are introduced in sequence.As presented,DPM can manipulate the as-prepared microstructures feasibly by taking the advantages of non-contacting and nondestructive characters.Moreover,the challenges and opportunities of DPM strategy are discussed in conclusion.

Photosensitive Azopolymer Brushes via Atom Transfer Radical Polymerization for Protein Sensing

Novel photosensitive azopolymer brushes were synthesized via surface initiated atom transfer radical polymerization using initiator self-assembled on Au surface. The chemical structures of azobenzene derivatives were confirmed by Fourier transform infrared spectroscopy （FTIR） and nuclear magnetic resonance spectroscopy （NMR）. The surface morphology of azopolymers via atom transfer radical polymerization （ATRP） for different time was investigated by atomic force microscopy （AFM）. Additionally, the photoisomerization of azopolymer was measured by ultraviolet-visible spectroscopy （UV-Vis）, The results indicate that such azopolymers can undergo trans-cis-trans photoisomerization efficiently by photo-irradiation with UV light. Furthermore, this photoisomerization property could also induce the reversible adsorption of bovine serum albumin （BSA） adsorption on azopolymer brush surfaces. This adsorption kinetics of the reversible process can be measured by surface plasmon resonance （SPR） spectroscopy in situ. It suggests that the protein biochips could be regenerated safely by UV irradiation rather than by being rinsed with chemical reagents.

Hyperbranched Azopolymer with Quadruple Responsibility

Simply constructing multiple responsive polymers with obvious shape and dimension variations on their assemblies upon different stimuli is still rarely reported.In this study,we report a hyperbranched polymer named HPAzoBAHB-star-PEG_(9) with quadruple-response to light,temperature,pH and oxidation stimuli.The polymer contains azobenzene chromophore,sulfide,amide and amine groups in its hydrophobic hyperbranched core,and the core is capped with hydrophilic polyethylene glycol(PEG_(9))arms.HPAzoBAHB-5tar-PEG_(9) could assemble into unusual leaf-like lamellar micelles at 25℃ under the guidance of orderly arranged H-aggregate of azobenzene moieties.These leaf-like lamellar micelles can transform into vesicles upon UV irradiation and lower temperature,or convert to smaller spherical micelles in acidic or oxidative environments,respectively,with the destroy of ordered azobenzene arrangements.This quadruple-responsive hyperbranched polymer is suitable to con struct multiple stimuli-resp on sive micro/nanostructures,or accurate delivery and release following subtle stimuli seque nces.