Diffusion Kurtosis MR Imaging of Invasive Breast Cancer: Correlations With Prognostic Factors and Molecular Subtypes.

BACKGROUND: The associations between diffusion kurtosis imaging (DKI)-derived parameters and clinical prognostic factors of breast cancer have not been fully evaluated; this knowledge may have implications for outcome prediction and treatment strategies. PURPOSE: To determine associations between quantitative diffusion parameters derived from DKI and diffusion-weighted imaging (DWI) and the prognostic factors and molecular subtypes of breast cancer. STUDY TYPE: Retrospective. POPULATION: A total of 383 women (mean age, 53.8 years; range, 31-82 years) with breast cancer who underwent preoperative breast MRI including DKI and DWI. FIELD STRENGTH/SEQUENCE: A 3.0 T; DKI using a spin-echo echo-planar imaging (EPI) sequence (b values: 200, 500, 1000, 1500, and 2000 sec/mm2 ), DWI using a readout-segmented EPI sequence (b values: 0 and 1000 sec/mm2 ) and dynamic contrast-enhanced breast MRI. ASSESSMENT: Two radiologists (J.Y.K. and H.S.K. with 9 years and 1 year of experience in MRI, respectively) independently measured kurtosis, diffusivity, and apparent diffusion coefficient (ADC) values of breast cancer by manually placing a regions of interest within the lesion. Diffusion measures were compared according to nodal status, grade, and molecular subtypes. STATISTICAL TESTS: Kruskal-Wallis test, Mann-Whitney U test with Bonferroni correction, receiver operating characteristic (ROC) analysis, and multivariate logistic regression analysis. (Statistical significance level of P < 0.05). RESULTS: All diffusion measures showed significant differences according to axillary nodal status and histological grade. Kurtosis showed significant differences among molecular subtypes. The luminal subtype (median 1.163) showed a higher kurtosis value compared to the HER2-positive (median 0.962) or triple-negative subtypes (median 1.072). ROC analysis for differentiating HER2-positive from luminal subtypes revealed that kurtosis yielded the highest area under the curve of 0.781. In multivariate analyses, kurtosis remained a significant factor associated with differentiation between HER2-positive and luminal (odds ratio [OR] = 0.993), triple-negative and luminal (OR = 0.995), and HER2-positive and triple-negative subtypes (OR = 0.994). DATA CONCLUSION: Quantitative diffusion parameters derived from DKI and DWI are associated with prognostic factors for breast cancer. Moreover, DKI-derived kurtosis can help distinguish between the molecular subtypes of breast cancer. EVIDENCE LEVEL: 4 TECHNICAL EFFICACY: 3.

Epitaxially Grown Ferroelectric PVDF-TrFE Film on Shape-Tailored Semiconducting Rubrene Single Crystal.

Epitaxial crystallization of thin poly(vinylidene fluoride-co-trifluoroethylene) (PVDF-TrFE) films is important for the full utilization of their ferroelectric properties. Epitaxy can offer a route for maximizing the degree of crystallinity with the effective orientation of the crystals with respect to the electric field. Despite various approaches for the epitaxial control of the crystalline structure of PVDF-TrFE, its epitaxy on a semiconductor is yet to be accomplished. Herein, the epitaxial growth of PVDF-TrFE crystals on a single-crystalline organic semiconductor rubrene grown via physical vapor deposition is presented. The epitaxy results in polymer crystals globally ordered with specific crystal orientations dictated by the epitaxial relation between the polymer and rubrene crystal. The lattice matching between the c-axis of PVDF-TrFE crystals and the (210) plane of orthorhombic rubrene crystals develops two degenerate crystal orientations of the PVDF-TrFE crystalline lamellae aligned nearly perpendicular to each other. Thin PVDF-TrFE films with epitaxially grown crystals are incorporated into metal/ferroelectric polymer/metal and metal/ferroelectric polymer/semiconductor/metal capacitors, which exhibit excellent nonvolatile polarization and capacitance behavior, respectively. Furthermore, combined with a printing technique for micropatterning rubrene single crystals, the epitaxy of a PVDF-TrFE film is formed selectively on the patterned rubrene with characteristic epitaxial crystal orientation over a large area.

Transparent and Flexible Graphene Pressure Sensor with Self-Assembled Topological Crystalline Ionic Gel.

This study demonstrates transparent and flexible capacitive pressure sensors using a high-k ionic gel composed of an insulating polymer (poly(vinylidene fluoride-co-trifluoroethylene-co-chlorofluoroethylene), P(VDF-TrFE-CFE)) blended with an ionic liquid (IL; 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) amide, [EMI][TFSA]). The thermal melt recrystallization of the P(VDF-TrFE-CFE):[EMI][TFSA] blend films develops the characteristic topological semicrystalline surface of the films, making them highly sensitive to pressure. Using optically transparent and mechanically flexible graphene electrodes, a novel pressure sensor is realized with the topological ionic gel. The sensor exhibits a sufficiently large air dielectric gap between graphene and the topological ionic gel, resulting in a large variation in capacitance before and after the application of various pressures owing to the pressure-sensitive reduction of the air gap. The developed graphene pressure sensor exhibits a high sensitivity of 10.14 kPa-1 at 20 kPa, rapid response times of <30 ms, and durable device operation with 4000 repeated ON/OFF cycles. Furthermore, broad-range detections from lightweight objects to human motion are successfully achieved, demonstrating that the developed pressure sensor with a self-assembled crystalline topology is potentially suitable for a variety of cost-effective wearable applications.

Aseptic Meningitis Following Second Dose of an mRNA Coronavirus Disease 2019 Vaccine in a Healthy Male: Case Report and Literature Review.

Vaccines are one of the most important strategies against pandemics or epidemics involving infectious diseases. With the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), there have been global efforts for rapid development of coronavirus disease 2019 (COVID-19) vaccine and vaccination is being performed globally on a massive scale. With rapid increase in vaccination, rare adverse events have been reported. Well-known neurological adverse events associated with COVID-19 vaccination include Guillain-Barré syndrome, myelitis, and encephalitis. However, COVID-19 vaccine-related aseptic meningitis has rarely been reported. A 32-year-old healthy man visited our hospital with a complaint of headache for 1 week. He had received the second dose of the BNT162b2 mRNA COVID-19 vaccine 2 weeks before the onset of headache. Since the initial cerebrospinal fluid (CSF) profile suggested viral meningitis, we started treatment with an antiviral agent. However, the symptoms and follow-up CSF profile on day 7 of hospitalization showed no improvement and SARS-CoV-2 IgG antibodies were detected in the CSF. We suspected aseptic meningitis associated with the vaccination and intravenous methylprednisolone (500 mg/day) was administered for 3 days. The symptoms improved and the patient was discharged on day 12 of hospitalization.

Visualization of nonsingular defect enabling rapid control of structural color.

Stimuli-interactive structural color (SC) of a block copolymer (BCP) photonic crystal (PC) uses reversible alteration of the PC using external fluids and applied forces. The origin of the diffusional pathways of a stimulating fluid into a BCP PC has not been examined. Here, we directly visualize the vertically oriented screw dislocations in a one-dimensional lamellar BCP PC that facilitate the rapid response of visible SC. To reveal the diffusional pathway of the solvent via the dislocations, BCP lamellae are swollen with an interpenetrated hydrogel network, allowing fixation of the swollen state and subsequent microscopic examination. The visualized defects are low-energy helicoidal screw dislocations having unique, nonsingular cores. Location and areal density of these dislocations are determined by periodic concentric topographic nanopatterns of the upper surface-reconstructed layer. The nonsingular nature of the interlayer connectivity in the core region demonstrates the beneficial nature of these defects on sensing dynamics.

Genotype-by-Sequencing Analysis of Mutations and Recombination in Pepper Progeny of Gamma-Irradiated Gametophytes.

The irradiation of dry seeds is the most widely-used irradiation method for improving seed-propagated crops; however, the irradiation of other tissues also has useful effects. The irradiation of plant reproductive organs, rather than seeds, for mutation breeding has advantages, such as producing non-chimeric progeny. However, the mutation frequency and spectrum produced using this method have not been analyzed on a genome-wide level. We performed a genotype-by-sequencing analysis to determine the frequencies of single-base substitutions and small (1-2 bp) insertions and deletions in hot pepper (Capsicum annuum L.) plants derived from crosses using gamma-irradiated female or male gametophytes. The progeny of irradiated gametophytes showed similar or higher DNA mutation frequencies, which were dependent on the irradiation dose and irradiated tissue, and less biased single base substitutions than progeny of irradiated seeds. These characteristics were expected to be beneficial for development of mutation population with a high frequency of small DNA mutations and performing reverse-genetics-based mutation screening. We also examined the possible use of this irradiation method in manipulating the meiotic recombination frequency; however, no statistically significant increase was detected. Our results provide useful information for further research and breeding using irradiated gametophytes.

[Thrombectomy of Femoro-Femoral Bypass Graft Occlusion Using the AngioJet Rheolytic Thrombectomy System and Embolic Protection Device: A Case Report]. / 대퇴-대퇴동맥 우회 인조혈관 폐색에서 AngioJet Rheolytic Thrombectomy Systemê³¼ ìƒ‰ì „ë³´í˜¸ê¸°êµ¬ë¥¼ 이용한 í˜ˆì „ì œê±°ìˆ : 증례 ë³´ê³ .

The authors report a successful thrombectomy using the AngioJet Rheolytic Thrombectomy System (AngioJet) and an embolic protection device in a patient with femorofemoral bypass graft occlusion. Lower extremity CT angiograms showed occlusion in the left-to-right femorofemoral bypass graft. A rheolytic thrombectomy using the AngioJet and balloon angioplasty restored blood flow to the right lower extremity, and distal embolization may be effectively prevented by placing an embolic protection device within the right superficial femoral artery during the procedure.

Computed tomography-based visual assessment of chronic obstructive pulmonary disease: comparison with pulmonary function test and quantitative computed tomography.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) has variable subtypes involving mixture of large airway inflammation, small airway disease, and emphysema. This study evaluated the relationship between visually assessed computed tomography (CT) subtypes and clinical/imaging characteristics. METHODS: In total, 452 participants were enrolled in this study between 2012 and 2017. Seven subtypes were defined by visual evaluation of CT images using Fleischner Society classification: normal, paraseptal emphysema (PSE), bronchial disease, and centrilobular emphysema (trace, mild, moderate and confluent/advanced destructive). The differences in several variables, including clinical, laboratory, spirometric, and quantitative CT features among CT-based visual subtypes, were compared using the chi-square tests and one-way analysis of variance. RESULTS: Subjects who had PSE had better forced expiratory volume in 1 second (FEV1) (P=0.03) percentage and higher lung density (P<0.05) than those with moderate to confluent/advanced destructive centrilobular emphysema. As the visual grade of centrilobular emphysema worsened, pulmonary function declined and modified Medical Research Council, COPD assessment test (CAT) score, and quantitative assessment (emphysema index and air trapping) increased. The bronchial subtype was associated with higher body mass index (BMI), better lung function and higher lung density. Participants with trace emphysema showed a rapid increase in functional small airway disease. CONCLUSIONS: Classifying subtypes using visual CT imaging features can reflect heterogeneity and pathological processes of COPD.

Effects of the Suboccipital Muscle Inhibition Technique on the Range of Motion of the Ankle Joint and Balance According to Its Application Duration: A Randomized Controlled Trial.

This study aimed to investigate the effects of suboccipital muscle inhibition technique (SMIT) on active range of motion (AROM) of the ankle joint, lunge angle (LA), and balance in healthy adults, according to the duration of its application. A total of 80 participants were randomly allocated to the 4-min suboccipital muscle inhibition (SMI) group (SMI_4M, n = 20), 8-min SMI group (n = 20), 4-min sham-SMI (SSMI) group (n = 20), and 8-min SSMI group (n = 20). Accordingly, the SMIT and sham SMIT were applied for 4 min or 8 min in the respective groups. AROM of dorsiflexion and LA were assessed, and a single leg balance test (SLBT) was performed before and after the intervention. AROM (4 min, p < 0.001; 8 min, p < 0.001), LA (4 min, p < 0.001; 8 min, p < 0.001), and SLBT (4 min, p < 0.001; 8 min, p < 0.001) significantly improved after SMI application. Compared with the SSMI group, the SMI group showed a significant increase in AROM (p < 0.001), LA (p < 0.001), and SLBT (p < 0.001). Except for SLBT (p = 0.016), there were no significant interactions between intervention and application duration. The results suggest that the SMIT, at durations of both 4 and 8 min, could be effective tools for improving AROM, LA, and balance.

Autonomous Surface Reconciliation of a Liquid-Metal Conductor Micropatterned on a Deformable Hydrogel.

Spreading liquid droplets on solid surfaces is a core topic in physical chemistry with significant technological implications. Liquid metals, which are eutectic alloys of constituent metal atoms with low melting temperatures, are practically useful, but difficult to spread on solid surfaces because of their high surface tension. This makes it difficult to use liquid metals as deformable on-board microcircuitry electrodes, despite their intrinsic deformability. In this study, it is discovered that eutectic gallium-indium (EGaIn) can be spread onto the surface of chemically cross-linked hydrogels consisting of aliphatic alkyl chains with numerous hydroxyl groups (OH), thus facilitating the development of directly micropatterned EGaIn electrodes. More importantly, EGaIn patterned on a hydrogel autonomously reconciliates its surface to form a firm hydrogel interface upon mechanical deformation of the hydrogel. This autonomous surface reconciliation of EGaIn on hydrogels allows researchers to reap the benefits of chemically modified hydrogels, such as reversible stretching, self-healing, and water-swelling capability, thereby facilitating the fabrication of superstretchable, self-healable, and water-swellable liquid-metal electrodes with very high conductance tolerance upon deformation. Such electrodes are suitable for a variety of deformable microelectronic applications.

Surface-Conformal Triboelectric Nanopores via Supramolecular Ternary Polymer Assembly.

A triboelectric nanogenerator (TENG) is of tremendous interest owing to its high energy efficiency with a simple device architecture and applicability to various materials. Most previous topological surface modifications introduced for further improving the performance of a TENG are detrimental because they require expensive and/or harsh (e.g., high temperature and acidity) postetching processes, which limit the material choice and design of its components. Herein, we demonstrate an one-step route for developing rapid wet-processable surface-conformal triboelectric nanoporous films (STENFs). Our method is based on a simple supramolecular assembly of a ternary polymer blend suitable for various conventional solution processes such as spin-, bar-, spray-, and dip-coating. The one-step wet process of a ternary solution produces thin large-area films in which self-assembled, ordered nanopores of approximately 33 nm in diameter are developed even without an additional etching process. The study reveals that the small amount of amine-terminated poly(ethylene oxide) added to the binary blend of sulfonic-acid-terminated poly(styrene) and poly(2-vinylpyridine) efficiently activates the formation of spontaneous nanopores as a pore-generating agent. Our STENF significantly enhances the open-circuit voltage up to 1.5 times higher than that of a planar one, leading to an improved power density of approximately 77 µW/cm2. The suitability for diverse conventional coating processes offers a convenient approach for fabricating high-performance STENFs not only on flat substrates such as metals, polymers, and oxides but also on topological ones including wrinkled, roughened surfaces, textile fibers, natural leaves, and fabrics over a large area.

3D touchless multiorder reflection structural color sensing display.

The development of a lightweight, low-power, user-interactive three-dimensional (3D) touchless display in which a human stimulus can be detected and simultaneously visualized in noncontact mode is of great interest. Here, we present a user-interactive 3D touchless sensing display based on multiorder reflection structural colors (SCs) of a thin, solid-state block copolymer (BCP) photonic crystal (PC). Full-visible-range SCs are developed in a BCP PC consisting of alternating lamellae, one of which contains a chemically cross-linked, interpenetrated hydrogel network. The absorption of a nonvolatile ionic liquid into the domains of the interpenetrated network allows for further manipulation of SC by using multiple-order photonic reflections, giving rise to unprecedented visible SCs arising from reflective color mixing. Furthermore, by using a hygroscopic ionic liquid ink, a printable 3D touchless interactive display is created where 3D position of a human finger is efficiently visualized in different SCs as a function of finger-to-display distance.

Rewritable, Printable Conducting Liquid Metal Hydrogel.

The development of high-performance printable electrical circuits, particularly based on liquid metals, is fundamental for device interconnection in flexible electronics, motivating numerous attempts to develop a variety of alloys and their composites. Despite their great potential, rewritable and printable electronic circuits based on liquid metals are still manufactured on demand. In this study, we demonstrate liquid metal-based hydrogels suitable for rewritable, printable electrical circuits. Our liquid metal hydrogels are based on sedimentation-induced composites of eutectic gallium-indium (EGaIn) particles in poly(ethylene glycol) diacrylate (PEGDA). The EGaIn particles are vertically phase-segregated in the PEGDA. When a composite surface with high EGaIn content is gently scratched, the surface covering PEGDA is removed, followed by the rupture of the native oxide layers of the particles, and the exposed EGaIn becomes conductive. The subsequent water-driven swelling of PEGDA on the scratched surface completely erases the conductive circuit, causing the system to reset. Our friction-responsive liquid metal hydrogel exhibits writing-erasing endurance for 20 cycles, with a dramatic change in the electrical resistance from metal (∼1 Ω) to insulator (∼107 Ω). By employing surface friction pen printing, we demonstrate mechanically flexible, rewritable, printable electrical conductors suitable for displays.

Prediction of return to productivity after severe traumatic brain injury: investigations of optimal neuropsychological tests and timing of assessment.

OBJECTIVES: (1) To examine predictive validity of global neuropsychological performance, and performance on timed tests (controlling for manual motor function) and untimed tests, including attention, memory, executive function, on return to productivity at 1 year after traumatic brain injury (TBI). (2) To compare predictive validity at 8 weeks versus 5 months postinjury. (3) To examine predictive validity of early degree of recovery (8wk-5mo postinjury) for return to productivity. DESIGN: Longitudinal, within subjects. SETTING: Inpatient neurorehabilitation and community. PARTICIPANTS: Patients (N=63) with moderate to severe TBI. INTERVENTIONS: Not applicable. PRIMARY OUTCOME: return to productivity at 1 year postinjury. Primary predictors: neuropsychological composite scores. Control variables: posttraumatic amnesia, acute care length of stay (LOS), Glasgow Coma Scale score, age, and estimated premorbid intelligence quotient. RESULTS: Return to productivity was significantly correlated with global neuropsychological performance at 5 months postinjury (P<.05) and showed a trend toward significance at 8 weeks. Performance on the untimed composite score, and more specifically executive and memory functions, mirrored this pattern. Logical Memory performance significantly predicted return to productivity, but not other memory tests. Timed tests showed no significance or trend at either time point. Early degree of recovery did not predict return to productivity. Among control variables, only acute care LOS was predictive of return to productivity. CONCLUSIONS: Findings validate utility of early neuropsychological assessment for predicting later return to productivity. They also provide more precise information regarding the optimal timing and test type: results support testing at 5 months postinjury on untimed tests (memory and executive function), but not simple attention or speed of mental processing. Findings are discussed with reference to previous literature.

Surface functionalized nanostructures via position registered supramolecular polymer assembly.

Versatile control of cylindrical nanostructures formed by supramolecular assembly of end-functionalized polymer blends is demonstrated not only in their orientation over large areas but also in their surface chemical functionalities. Two binary blends consisting of supramolecular analogues of diblock copolymers with complementary end-sulfonated and aminated groups are investigated, viz., mono-end-functionalized polymers of (i) one-end-sulfonated polystyrene (SPS) and one-end-aminated poly(butadiene) (APBD) and (ii) one end-aminated polystyrene (APS) and one end-sulfonated poly(butadiene) (SPBD). The orientation of the cylinders with respect to the substrate surface depends on the solvent annealing time; either hexagonally ordered vertical cylinders or in-plane ones are readily obtained by controlling the solvent annealing time. Selective chemical etching of one of the polymers provides four different chemically modified nanostructures, viz., hexagonally ordered cylindrical holes and cylindrical posts with either sulfonate or amine surface functional groups. Additional supramolecular assembly is successfully achieved by solution coating either polymers or organic dyes that complementarily interact with the functional groups on the nanostructures. Furthermore, the supramolecularly assembled nanostructures are controlled by confining them to topographically pre-patterned Si substrates with pattern geometries of various shapes and sizes to produce globally ordered vertical or in-plane cylinders with chemical functionalities on their surfaces.

Electroluminescent Pressure-Sensing Displays.

Simultaneous sensing and visualization of pressure provides a useful platform to obtain information about a pressurizing object, but the fabrication of such interactive displays at the single-device level remains challenging. Here, we present a pressure responsive electroluminescent (EL) display that allows for both sensing and visualization of pressure. Our device is based on a two-terminal capacitor with six constituent layers: top electrode/insulator/hole injection layer/emissive layer/electron transport layer/bottom electrode. Light emission upon exposure to an alternating current field between two electrodes is controlled by the capacitance change of the insulator arising from the pressure applied on top. Besides capacitive pressure sensing, our EL display allows for direct visualization of the static and dynamic information of position, shape, and size of a pressurizing object on a single-device platform. Monitoring the pressurized area of an elastomeric hemisphere on a device by EL enables quantitative estimation of the Young's modulus of the elastomer, offering a new and facile characterization method for the mechanical properties of soft materials.

Micropatterned Pyramidal Ionic Gels for Sensing Broad-Range Pressures with High Sensitivity.

The development of pressure sensors that are effective over a broad range of pressures is crucial for the future development of electronic skin applicable to the detection of a wide pressure range from acoustic wave to dynamic human motion. Here, we present flexible capacitive pressure sensors that incorporate micropatterned pyramidal ionic gels to enable ultrasensitive pressure detection. Our devices show superior pressure-sensing performance, with a broad sensing range from a few pascals up to 50 kPa, with fast response times of <20 ms and a low operating voltage of 0.25 V. Since high-dielectric-constant ionic gels were employed as constituent sensing materials, an unprecedented sensitivity of 41 kPa-1 in the low-pressure regime of <400 Pa could be realized in the context of a metal-insulator-metal platform. This broad-range capacitive pressure sensor allows for the efficient detection of pressure from a variety of sources, including sound waves, a lightweight object, jugular venous pulses, radial artery pulses, and human finger touch. This platform offers a simple, robust approach to low-cost, scalable device design, enabling practical applications of electronic skin.

Printable and Rewritable Full Block Copolymer Structural Color.

Structural colors (SCs) of photonic crystals (PCs) arise from selective constructive interference of incident light. Here, an ink-jet printable and rewritable block copolymer (BCP) SC display is demonstrated, which can be quickly written and erased over 50 times with resolution nearly equivalent to that obtained with a commercial office ink-jet printer. Moreover, the writing process employs an easily modified printer for position- and concentration-controlled deposition of a single, colorless, water-based ink containing a reversible crosslinking agent, ammonium persulfate. Deposition of the ink onto a self-assembled BCP PC film comprising a 1D stack of alternating layers enables differential swelling of the written BCP film and produces a full-colored SC display of characters and images. Furthermore, the information can be readily erased and the system can be reset by application of hydrogen bromide. Subsequently, new information can be rewritten, resulting in a chemically rewritable BCP SC display.

Solvent-Assisted Gel Printing for Micropatterning Thin Organic-Inorganic Hybrid Perovskite Films.

While tremendous efforts have been made for developing thin perovskite films suitable for a variety of potential photoelectric applications such as solar cells, field-effect transistors, and photodetectors, only a few works focus on the micropatterning of a perovskite film which is one of the most critical issues for large area and uniform microarrays of perovskite-based devices. Here we demonstrate a simple but robust method of micropatterning a thin perovskite film with controlled crystalline structure which guarantees to preserve its intrinsic photoelectric properties. A variety of micropatterns of a perovskite film are fabricated by either microimprinting or transfer-printing a thin spin-coated precursor film in soft-gel state with a topographically prepatterned elastomeric poly(dimethylsiloxane) (PDMS) mold, followed by thermal treatment for complete conversion of the precursor film to a perovskite one. The key materials development of our solvent-assisted gel printing is to prepare a thin precursor film with a high-boiling temperature solvent, dimethyl sulfoxide. The residual solvent in the precursor gel film makes the film moldable upon microprinting with a patterned PDMS mold, leading to various perovskite micropatterns in resolution of a few micrometers over a large area. Our nondestructive micropatterning process does not harm the intrinsic photoelectric properties of a perovskite film, which allows for realizing arrays of parallel-type photodetectors containing micropatterns of a perovskite film with reliable photoconduction performance. The facile transfer of a micropatterned soft-gel precursor film on other substrates including mechanically flexible plastics can further broaden its applications to flexible photoelectric systems.

Electrically Tunable Soft-Solid Block Copolymer Structural Color.

One-dimensional photonic crystals based on the periodic stacking of two different dielectric layers have been widely studied, but the fabrication of mechanically flexible polymer structural color (SC) films, with electro-active color switching, remains challenging. Here, we demonstrate free-standing electric field tunable ionic liquid (IL) swollen block copolymer (BCP) films. Placement of a polymer/ionic liquid film-reservoir adjacent to a self-assembled poly(styrene-block-quaternized 2-vinylpyridine) (PS-b-QP2VP) copolymer SC film allowed the development of red (R), green (G), and blue (B) full-color SC block copolymer films by swelling of the QP2VP domains by the ionic liquid associated with water molecules. The IL-polymer/BCP SC film is mechanically flexible with excellent color stability over several days at ambient conditions. The selective swelling of the QP2VP domains could be controlled by both the ratio of the IL to a polymer in the gel-like IL reservoir layer and by an applied voltage in the range of -3 to +6 V using a metal/IL reservoir/SC film/IL reservoir/metal capacitor type device.