Preparation And Performance Of Structural Colored Fiber Based On PNIPAM Microgel

Hydrogels are typical polymer materials with three dimensional networkstructures，which have been studied extensively because of their ability to simulateself-tissues and to swell or collapse reversibly in response to external stimuli. Thestructural color materials prepared by intelligent hydrogels are sensitive totemperature, salt, pH and other intelligence features have been one of the extensivelyareas of scientific research in recently years.In this paper, PNIPAM-Co-AAc and PNIPAM-Co-HEAC block copolymerhydrogel materials were synthesized by emulsion polymerization method. Themorphology, structure, particles size, Zeta potential and functional groups of thesetwo hydrogel materials were characterized by FE-SEM, Static/dynamic LightScattering instrument, Size/zeta Potential apparatus and FT-IR. The results show thatthe monodispersed PNIPAM-Co-AAc and PNIPAM-Co-HEAC hydrogelnanoparticles were obtained with particle size in the range of200-450nm, and thesurface of microspheres carry negative charge; with the increase of AAc/HEACcontent, the size of the resulting nanogels increased. Further study on the hydrogelopal prepared by evaporation based on PNIPAM-Co-HEAC nanoparticles shows thatthe hydrogel opal has colorful colors. The structurally colored hydrogel film based onthe PNIPAM-Co-AAc nanoparticles were prepared by gravity deposition methodresponded to external temperature stimuli. The optical fiber spectrometer and opticalmicroscopy were adopted to characterize the structurally colored hydrogel film, andthe temperature sensitive ability of film was found in the experiment. With theincrease of temperature, the hydrogel film’s color from green(25℃) blue shift to blue(35℃), and changed to white (45℃) at last. Based on above researches, PNIPAM-Co-AAc and PNIPAM-Co-HEACnanoparticles were self-assemble on the surface of the cleaned carbon fiber byelectrophoretic deposition method to fabricate structurally colored carbon fibers,respectively. Field emission scanning electron microscopy, optical microscopy andoptical fiber spectrometer were adopted to characterize the structurally colored fibers.By applying a voltage and changing electrophoresis time, these fibers exhibit differentstructural colors with red, green, blue. The assembly time of colloidal crystal isimproved from a few minutes to tens of seconds. Greatly improve the efficiency ofthe colloidal crystal assembly.Further study of the structurally colored fibers response to the polar organic gas,the purple colored fiber was put into a closed device with ethanol, acetone atmosphere,respectively. With the time increasing, the color changed from purple to green. Whenthe gas disappeared, the fiber’s color changed back to purple. That is to say thestructurally colored fibers have good ability to response to polar gas. The results showthat under the condition of no external power supply, the structurally colored fibersresponse to external stimuli by changing color. This advantage has potential to beapplied in passive wearable sensors.