Fabrication of Patterned Images in Photochromic Organic Microfibers

Reversible color modulation of luminescent conjugated polymers based on a chemical redox mechanism and applications in rewritable paper and multiple information encryption

Reversible color modulation plays a key role in the field of information recording and encryption, but for the common colorful conjugated polymer materials, currently a convenient method to achieve their reversible color modulation is still lacking. Herein, six luminescent conjugated polymers P1 to P6 were successfully designed and synthesized, all of which could realize reversible color modulation through a similar reversible chemical redox behavior accompanied by reversible color and fluorescence changes. The same absorption spectral changes as those under electrochemical redox conditions strongly confirmed that these polymers underwent reversible redox reactions in the Fe³⁺ and H₂O system, which happened spontaneously according to the theoretical analysis of the reaction thermodynamics. Based on the reversible color modulation in the Fe³⁺ and H₂O system, polymers P1, P2 and P3, with different colors (yellow, orange and red) and fluorescence emissions, were successfully applied as rewritable paper with multi-color and multi-fluorescence printing as well as long-term recording capabilities. Meanwhile, polymers P1, P4, P5 and P6, which showed similar green fluorescence and yellow color but different oxidation potentials, were also introduced to accomplish multiple encryption and decryption of information, based on the step-by-step selective oxidation of the four polymers by adjusting the concentration of Fe³⁺.

Three-Component Regio- and Stereoselective Polymerizations toward Functional Chalcogen-Rich Polymers with AIE-Activities

Polymers containing rich chalcogen elements are rarely reported due to the lack of facile synthesis methods. Herein, a novel multicomponent polymerization route toward chalcogen-rich polymers was introduced. A series of poly(vinyl sulfones) (PVSs) were synthesized at room temperature using readily prepared monomers. PVSs were generated with high regio- and stereo-selectivity in high yields (up to 92.3%). Rich chalcogen elements endowed PVSs with distingctive multifunctionalities. The PVSs possessed good solubility and film-forming ability. Their thin films exhibited outstanding refractive indices up to 1.8062 at 550.0 nm together with good optical transparency in the visible region. Thin films of some polymers can also be fabricated into well-resolved fluorescent photopatterns by photolithography. Thanks to the unique redox properties of selenium, postmodification by oxidation reaction of P1a/2/3a successfully eliminates the caused heavy atom effect and endow resulting polymers with novel functionality as fluorescent bioprobes for cellular imaging.

Functional Materials and Systems for Rewritable Paper

"Paper" has greatly contributed to the development and spread of civilization. Even in today's "digitalized" world, paper continues to play a key role in socioeconomic growth, as is evidenced by the growth in global paper consumption. Unfortunately, the use of paper has its cost in terms of the exhaustion of world's natural resources. Consequently, new, cost-effective technologies that preserve natural resources are required for this purpose. Functional materials have revolutionized the way people think about developing new technologies. Especially important in this regard are "smart reactive materials," which are capable of actively responding to external stimuli such as heat, light, mechanical stress, and specific molecular orientations. Moreover, functionalized chromogenic materials, which undergo reversible color switching upon external stimulation, have attracted great attention in the context of developing rewritable paper. Here, investigations of various materials and systems that are devised for use as rewritable paper are reviewed with the hope that the coverage will stimulate and guide future studies in this area.

Photochromic spiropyran-embedded PDMS for highly sensitive and tunable optochemical gas sensing

A highly sensitive, tunable, flexible and microfluidic compatible gas sensor was developed based on a photochromic spiropyran-embedded PDMS composite.