A new class of materials for optical data storage and security data encryption is reported. Multidye colloid particles comprising different dyes in different phases are employed as the building blocks to produce a multicolored multiphase polymeric material. The incorporation of dyes in different phases minimizes energy transfer, provides selective dye photobleaching, and allows storage of different data on a single spot (see Figure and also cover).

We report the application of the "internal trigger" approach to multistep microfluidic polymerization reactions conducted in droplets, namely, polyaddition and polycondensation. We hypothesized and experimentally established that heat generated in an exothermic free radical polymerization of an acrylate monomer (Reaction 1) triggers the polycondensation of the urethane oligomer (Reaction 2). Completion of two microfluidic polymerization reactions led to the continuous synthesis of polymer particles with an interpenetrating polymer network (IPN) structure. Use of this microfluidic synthesis allowed us (i) to conduct efficient screening of the compositions of the monomer mixtures; (ii) to achieve control of the stoichiometric ratios of reactants in Reaction 2 by varying the flow rates of liquids; (iii) to reach control over the morphology of the resulting particles; and (iv) to produce polymer particles with a narrow size distribution and a predetermined size.

We describe the miscibility of blends involving poly(ethylhexyl methacrylate) [PEHMA] latex copolymers using the direct nonradiative energy transfer (DET) technique. When the polymers in both components of a blend are PEHMA homopolymers, we obtain a fully mixed film. When one of the components in the blend is replaced with a PEHMA copolymer containing 5 mol % tert-butylcarbodiimidoethyl methacrylate (tBCEMA), we also obtain a fully mixed film. However, if a PEHMA copolymer containing 11 mol % methacrylic acid (MAA) is mixed with PEHMA homopolymer, the miscibility between the polymers is limited and is reduced further when the amount of MAA is increased to 20 mol %. Using a distribution model for energy transfer, we were able to determine the evolution of the interface thickness with annealing time. The maximum interface thickness attained in these blends decreases from δ ) 15 nm to δ ) 8 nm when the content of MAA in the blends increases from 11 mol % to 20 mol %. A freshly formed solvent-cast film prepared from a 1:1 blend of the PEHMA copolymer containing 11 mol % MAA and the PEHMA copolymer containing 5 mol % tBCEMA exhibits some polymer segregation. This persists in the solid film when the film is annealed for short times (20 min) at 60 °C. Over longer times, mixing of the copolymers occurs and reaches completion. We attribute this increase in miscibility to the formation of graft copolymer, which serves as a compatibilizing agent, through the reaction between the -COOH and -NdCdC-groups. When a film of the same composition is prepared from a blend of the two latex dispersions and annealed, a fully mixed film also results.

We report the design, synthesis, and application of a multidye polymer nanocomposite with respect to high-density 3D optical data storage and security labeling. Core−shell latex particles containing visible and near-IR dyes in the core-forming polymer and the shell-forming polymer were used as the functional building blocks to produce a multicolored multiphase polymeric material with a minimized energy transfer between the dyes. The core−shell particles were prepared by copolymerizing dye-labeled monomers with the hosting polymer. Data recording was achieved using confocal fluorescent microscopy by selective photobleaching of the dyes periodically distributed in the nanocomposite film.