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Anti-reflection (AR) coatings designed for glass and other rigid, inorganic substrates are commercially available; however, these inorganic AR coatings tend to crack or delaminate on flexible substrates. A polymeric film with a gradient refractive index (GRIN) profile would make an ideal AR coating for flexible substrates, but such coatings are challenging to fabricate using traditional, solution-based techniques. Emulsion-based resonant infrared, matrix-assisted pulsed laser evaporation (RIR-MAPLE) offers a straightforward approach to enabling the desired GRIN profile in polymeric materials. Two homopolymers (polystyrene (PS) and poly(methyl methacrylate) (PMMA)) are deposited as a blend and one component (PMMA) is dissolved, leaving behind a porous PS film. The porosity and refractive index (RI) are controlled by the volume ratio of the two homopolymers in the film. Structural and optical characterizations, as well as comparison to modeled optical properties, confirm that porous films fabricated from polymer blends deposited by RIR-MAPLE behave as effective media over most of the visible spectrum. While evidence for the partial collapse of the porous polymer networks is observed, the RI of the porous films is reduced from that of the bulk material. Importantly, these studies demonstrate that RIR-MAPLE should enable broadband, omnidirectional, polymeric AR coatings appropriate for flexible substrates. [ABSTRACT FROM AUTHOR]

Several polystyrene‐b‐poly(methyl methacrylate) (PS‐b‐PMMA) and polyisoprene‐b‐PMMA (PI‐b‐PMMA) block copolymers are studied with high‐resolution diffusion ordered spectroscopy (DOSY) in order to quantify the amounts and molar masses of the copolymers and the containing homopolymers. These studies are particularly challenging because these homopolymers and one block of the copolymers consist of the same monomer type with different molar masses and compositions and cause a total overlap of these polymer components in the NMR spectra. However, DOSY can be proven as a powerful tool for separation and quantification of these moieties. Whereas exponential fittings only deliver averaged diffusion data, biexponential fittings of the individual magnetization curves can separate the overlapping polymer parts. This DOSY approach can be successfully tested for different blends of PS as well as PS and PS‐b‐PMMA of different molar masses and weighed compositions. The DOSY separation is also compared to size exclusion chromatography (SEC). In the case of the PS‐b‐PMMA and PI‐b‐PMMA block copolymers, DOSY identifies the contaminations with homopolymers, quantifies their individual amounts as well as determines the molar masses of both the copolymers and homopolymers. Two mathematical evaluations are used for quantifying these homopolymers with DOSY. These results are compared with the online coupling of SEC and NMR. [ABSTRACT FROM AUTHOR]

For block copolymer (BCP)/homopolymer self‐assembly systems, the molecular weight of homopolymers is usually lower than that of BCPs. Herein, the cooperative self‐assembly of polystyrene‐b‐poly(ethylene glycol) (PS‐b‐PEG) BCPs with high‐molecular‐weight polystyrene (PS) homopolymers is reported. The molecular weight of PS homopolymers is 3–63 times that of the PS blocks. Typically, a spherical micelle–vesicle–large sphere morphology transition is observed by increasing the weight fraction of PS homopolymers in the polymer mixtures (fHP). Dynamic process studies reveal that with adding water to the solution of polymer mixtures in organic solvent, the homopolymers first collapse into globules, and their size increases with fHP and the molecular weight. Then these PS globules cooperatively self‐assemble with the PS‐b‐PEG BCPs. Depending on their size, these PS globules play different roles in the self‐assembly process. Small PS globules act as morphology modifiers inducing the micelle–vesicle transition, while large PS globules serve as self‐assembly templates for PS‐b‐PEG resulting in large spheres. High‐molecular‐weight polystyrene (PS) homopolymers are found in the form of globules to cooperatively self‐assemble with polystyrene‐b‐poly(ethylene glycol) (PS‐b‐PEG) block copolymers. Depending on their size, these PS globules play different roles. Small PS globules act as morphology modifiers inducing the micelle–vesicle transition, while large PS globules serve as self‐assembly templates for PS‐b‐PEG resulting large spheres. [ABSTRACT FROM AUTHOR]