Background color dependent photonic multilayer films for anti-counterfeiting labeling.

A new concept for anti-counterfeiting security films that utilize the humidity from human breath to reveal a QR code on color-tunable one-dimensional (1D) PC films is presented. The 1D PC film was fabricated on a transparent polyethylene terephthalate (PET) substrate via sequential alternate layer deposition of photo-crosslinkable poly(2-vinylnaphthalene-co-benzophenone acrylate) (P(2VN-co-BPA)) and quaternized poly(4-vinylpyridine-co-benzophenone acrylate) (P(4VP-co-BPA)) (P4QP-51%). The films exhibited remarkable color transitions with reliable reversibility and reproducibility. Films placed on a black background exhibited the full visible spectrum color in a high humidity environment. Additionally, films placed on a white background displayed three different composite colors, including yellow, magenta, and cyan. These films with vivid color transitions in a high humidity environment can be applied as anti-counterfeiting films. A hidden QR code was also laser printed on the initial PC film to enhance the film's anti-counterfeiting security capabilities. These colorimetric 1D PC films can be used as anti-counterfeiting labels and for information storage.

Use of Core-Cross-Linked Polymeric Micelles Induced by the Selective Detection of Cu(II) Ions for the Sustained Release of a Model Drug.

A well-defined amphiphilic phenylthiosemicarbazone-based block copolymer was successfully synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization, followed by postpolymerization modification. Poly( N,N-dimethylacrylamide) (pDMA) was synthesized via RAFT polymerization of N,N-dimethylacrylamide (DMA). The resulting pDMA macrochain transfer agent was further extended using 3-vinylbenzaldehyde (VBA) to yield the poly[( N,N-dimethylacrylamide)- b-(3-vinylbenzaldehyde)] [p(DMA- b-VBA)] block copolymer. The aldehyde groups of p(DMA- b-VBA) were then made to react with 4-phenylthiosemicarbazide to yield the target block copolymer poly{ N,N-dimethylacrylamide- b-[ N-phenyl-2-(3-vinylbenzylidene)hydrazine carbothioamide]} [p(DMA- b-PVHC)]. p(DMA- b-PVHC) self-assembled in aqueous solution to yield polymeric micelles that comprise a pDMA block that forms a hydrophilic shell and a pPVHC block that forms a hydrophobic core. p(DMA- b-PVHC) micelles can detect Cu(II) ions which can be determined by a color change from colorless to yellow induced by the formation of coordination complexes between Cu(II) ions and the phenylthiosemicarbazone units of p(DMA- b-PVHC). As Cu(II) ions slowly penetrated the core of p(DMA- b-PVHC) micelles, these cores cross-linked with each other, which in turn resulted in the micelle particles swelling in water. Upon the addition of Cu(II) ions to a solution of p(DMA- b-PVHC) micelles encapsulating the hydrophobic model drug coumarin 102, this drug was released from the micelles in a sustained manner due to the gradual swelling of the cross-linked micelle cores caused by the slow penetration of Cu(II) ions.