For ultrahigh-density storage media and D-RAM, the feature size of lithography should be much reduced (say less than 10 nm). Though some research groups reported feature size of 5–6 nm, further reduced feature size is needed for next-generation lithography. We synthesized, via a reversible addition–fragmentation chain-transfer polymerization, polydihydroxystyrene-block-polystyrene (PDHS-b-PS) copolymers showing lamellar and cylindrical microdomains by adjusting the volume fraction of PS block (f PS). We found that the Flory–Huggins interaction parameter (χ) between PDHS and PS was very large, 0.7 at 170 °C. Because of the huge χ, the lamellar domain spacing (L) of PDHS-b-PS with a total molecular weight of 2.1 kg mol–1 and f PS = 0.5 was only 5.9 nm; thus, a sub-3 nm feature size (half-pitch) was successfully obtained. Furthermore, PDHS-b-PS with a molecular weight of 4.2 kg mol–1 and f PS = 0.79 showed hexagonally packed cylinders with 4 nm diameter. We also obtained thin films of PDHS-b-PS with cylindrical microdomains, showing 8.8 nm center-to-center spacing. Furthermore, we fabricated ultrahigh-density ZrO2 nanowire arrays from the cylindrical monolayer thin films via atomic layer deposition, indicating an applicability of PDHS-b-PS for next-generation lithography.

We introduce a novel grafting-through polymerization strategy to synthesize dynamic bottlebrush polymers and elastomers in one step using light to construct a disulfide-containing backbone. The key starting materialα-lipoic acid (LA)is commercially available, inexpensive, and biocompatible. When installed on the chain end(s) of poly(dimethylsiloxane) (PDMS), the cyclic disulfide unit derived from LA polymerizes under ultraviolet (UV) light in ambient conditions. Significantly, no additives such as initiator, solvent, or catalyst are required for efficient gelation. Formulations that include bis-LAfunctionalized cross-linker yield bottlebrush elastomers with high gel fractions (83−98%) and tunable, supersoft shear moduli in the ∼20− 200 kPa range. An added advantage of these materials is the dynamic disulfide bonds along each bottlebrush backbone, which allow for light-mediated self-healing and on-demand chemical degradation. These results highlight the potential of simple and scalable synthetic routes to generate unique bottlebrush polymers and elastomers based on PDMS.

We investigated, via small-angle X-ray scattering and transmission electron microscopy, the morphologies of binary blend of polyisoprene-b-polystyrene-b-poly­(2-vinylpyridine) (ISP) triblock terpolymer and polyisoprene-b-polystyrene (IS) diblock copolymer. An asymmetric ISP with volume fractions (f) of 0.12, 0.75, and 0.13 for PI, PS, and P2VP blocks, respectively, showed a new morphology: coexistence of spheres and cylinders with tetragonal packing. Asymmetric IS with f I = 0.11 and f S = 0.89 showed conventional body-centered cubic spherical microdomains. Very interestingly, a binary blend of ISP and IS with overall volume fractions of f I = 0.12, f S = 0.79, and f P = 0.09 exhibited core–shell double gyroid (CSG: Q230 space group), where PI consists of thin core and PS forms thick shell, while P2VP becomes thin matrix. It is very unusual to form CSG even at highly asymmetric volume fractions.

We have introduced a facile synthetic route for well-defined [poly(3-dodecylthiophene)] 2 poly(methyl methacrylate) miktoarm star copolymer (P3DDT 2 PMMA) by using a click reaction. For this purpose, PMMA with two ethynyl groups (PMMA-(≡) 2 ) and ω-azidopropyl-P3DDT were synthesized. We found that the use of alkyl linker (here, propyl group) between P3DDT and azido group is very essential to minimize the steric hindrance arising from bulky side group in P3DDT during the click reaction. When we employed a slightly excess amount of the ω-azidopropyl-P3DDT, we obtained a well-defined P3DDT 2 PMMA with a narrow molecular weight distribution (polydispersity index <1.20) after selective removal of the unreacted ω-azidopropyl-P3DDT in a crude product by using column chromatography. We also investigated self-assembled structure of P3DDT 2 PMMA by small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). P3DDT 2 PMMA with weight fraction of P3DDT block (w P3DDT ) of 0.33 had lamellar microdomains, while a linear diblock copolymer (P3DDT-b-PMMA) with w P3DDT = 0.37 showed cylindrical microdomains. Also, P3DDT 2 PMMA with w P3DDT = 0.59 showed the HEX cylindrical microdomains of PMMA in the P3DDT matrix, whereas P3DDT-b-PMMA with w P3DDT = 0.56 exhibited lamellar microdomains. More interestingly, P3DDT 2 PMMA with w P3DDT of 0.76 showed hexagonally packed PMMA cylinders in the P3DDT matrix at molten state, and this morphology was maintained even after crystallization of the P3DDT block. This behavior is quite different from linear P3DDT-b-PMMA diblock with the same weight fraction of P3DDT because the latter shows fibril structures after P3DDT crystallization. These results imply that controlling the molecular architecture is an effective way to tune the morphology of P3AT-containing block copolymers. ■ INTRODUCTIONRegioregular poly(3-alkylthiophene) (P3AT) is one of the most attractive semicrystalline polymers due to its high charge carrier mobility and good solubility in organic solvents. 1−3 To achieve high performance organic electronic devices, one challenge is fabrication of P3AT nanostructures with nanometer length scale. 4,5 For this purpose, various block copolymers consisting of P3AT and coil blocks have been synthesized 6−15 because of their self-assembly ability to form periodic nanostructures. 16−18 However, most poly(3-hexylthiophene) (P3HT)-containing block copolymers usually exhibit only fibril morphology due to strong rod/rod interaction of P3HT. 18−22 In the rod−coil block copolymer system, the phase behavior is determined by the competition between rod/rod interaction (μ) of rod block and the segregation power (governed by the Flory's segmental interaction parameter χ) between rod and coil blocks. 23−25 These two factors are adjusted by varying the composition of each block or tuning the crystallinity of the rod moiety. Some research groups used P3AT with longer (or bulkier) alkyl side chain than P3HT to depress the crystallization of the rod block. Ho et al. 26 reported various na...

Broadband perfect absorbers have been intensively researched for decades because of their near-perfect absorption optical property that can be applied to diverse applications. Unfortunately, achieving large-scale and heat-tolerant absorbers has been remained challenging work because of costly and time-consuming lithography methods and thermolability of materials, respectively. Here, we demonstrate a thermally robust titanium nitride broadband absorber with >95% absorption efficiency in the visible and near-infrared region (400–900 nm). A relatively large-scale (2.5 cm × 2.5 cm) absorber device is fabricated by using a fabrication technique of multiple-patterning colloidal lithography. The optical properties of the absorber are still maintained even after heating at the temperatures >600 ∘C. Such a large-scale, heat-tolerant, and broadband near-perfect absorber will provide further useful applications in solar thermophotovoltaics, stealth, and absorption controlling in high-temperature conditions.

We obtained the end-on orientation of poly­(3-dodecylthiophene) (P3DDT) chains where the main chains are vertically oriented on a substrate by synthesizing poly­(3-dodecyl­thiophene)-block-poly­(3-(2-(2-(2-methoxy­ethoxy)­ethoxy)­ethoxy)­methyl thiophene) copolymer (P3DDT-b-P3TEGT) with two different weight fractions of P3DDT block (w P3DDT = 0.48 and 0.65). Both block copolymers showed well-ordered lamellar microdomains in bulk, verified by small-angle X-ray scattering (SAXS). Because of the high incompatibility of the two blocks, P3DDT-b-P3TEGT thin films prepared by spin-coating on a substrate followed by thermally annealing showed parallel oriented lamellar microdomains to the substrate. Hydrophilic P3TEGT microdomains were located at the substrate/polymer interface, while hydrophobic P3DDT microdomains were located at the polymer/air interface. Thus, both P3DDT and P3TEGT backbone chains were oriented perpendicularly to the lamellar layer (namely, film thickness direction), and the end-on orientations of P3DDT and P3TEGT chains were obtained. The hole mobility was measured by fabricating a space-charge-limited current (SCLC) device. P3DDT-b-P3TEGT showed much enhanced mobility compared with the device made of neat P3DDT film with edge-on orientation, indicating that end-on orientation is very effective for improving the hole mobility along the vertical direction.

Bottlebrush elastomers have attracted significant attention as a class of super‐soft materials with a storage modulus (G′) less than the intrinsic entanglement shear modulus (Ge), but current processing strategies have been limited to molding or extrusion‐based 3D printing. Here, the ability to 3D print bottlebrush elastomers via digital light processing (DLP) is demonstrated through the design of novel resin components and building blocks. In particular, mono‐telechelic poly(ethylene glycol) (PEG) macromonomers with a 1,2‐dithiolane end group derived from α‐lipoic acid (LA) undergo fast and efficient copolymerization with PEG diacrylates under light (≤405 nm) in the presence of a photoinitiator to generate crosslinked bottlebrush networks containing dynamic disulfide backbones. This allows objects that are both super‐soft and solvent‐free to be printed with a commercial DLP printer. The resulting materials undergo dynamic disulfide exchange when exposed to ultraviolet light (365 nm) or elevated temperatures, facilitating reprocessing and postfabrication healing. These results establish a simple design strategy for the preparation of DLP resins based on natural building blocks (α‐lipoic acid), leading to materials with unique properties that broaden the utility of light‐based 3D printing with user‐friendly chemistry.

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