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New π-conjugated polymers based on dithienyl-diketopyrrolopyrrole (dtDPP) were synthesized by direct arylation polymerization, that is, poly(dtDPP), poly(dtDPP-FL), and poly(dtDPP-TPA). They reveal...

In this study, we reports the first quantification details of the pencil hardness, eraser abrasion resistance and steel wool abrasion resistance of optically-transparent and biaxially-oriented poly(ethylene terephthalate) (PET) films in various thicknesses before and after hard coating (HC) and/or optically clear adhesive (OCA) coating. Surprisingly, the PET base films were determined to exhibit unrealistically very low hardness and abrasion resistances although their stress-strain behavior followed a ductile and tough plastic nature as a high performance engineering plastic: the pencil hardness was only ≤ 9B even at a low loading force, 0.100 kgf, and the onset loading force to cause scratches was far below 0.013 kgf in both eraser and steel wool abrasions. These collectively confirmed that, without surface protections, PET base films are not suitable for any advanced applications. Such the low hardness and poor abrasion resistances could be improved substantially by only thin HC coating of di(trimethylolpropane) tetraacrylate (HC-a, an ultraviolet curable acrylic resin). In addition, the OCA coating based on an acrylic copolymer adhesive provided adhesion function to the PET films, showing excellent adhesion strength onto chemically-toughened glass. However, the OCA layer causes cushioning effect because of its easy plastic deformation nature, making negative impact on the hardness and abrasion resistance performances of the PET film. Thus, the OCA coating should be thinned until retaining good adhesion to adherends. Overall, PET films coated with HC and/or OCA are suitable for advanced applications in various fields including smart phones, foldable phones, and flexible display devices.

This study reports the first morphology and crystalline structure details of iron oxide nanoparticles in a comprehensive manner. A series of iron oxide nanoparticles were synthesized in 1-octadecene from iron(III) acetylacetonate with the aid of oleic acid surfactant and then followed by post thermal processes. Quantitative small and wide angle X-ray scattering analyses using synchrotron radiation sources were performed together with electron microscopy, infrared spectroscopy and thermogravimery, providing morphology and crystalline structure details. Larger size of nanoparticles are synthesized by higher loading of the surfactant. Prolate ellipsoidal nanoparticles, rather than spherical particles, are always synthesized in single unimodal and narrow size distribution. The individual particles are composed of core, core-shell interface, shell, and shell-surfactant interface, regardless of the sizes. Magnetite-like crystalline phases are predominant. In addition, wuestite-like crystalline phases are discernible as minor components. For a given particle, the size and distribution are varied very little by the post thermal proccesses. Nevertheless, the other morphology characteristics, as well as the crystalline phases are significantly influenced through the post thermal process with a mixture of nitrogen and oxygen. In particular, the core part is thickened, the density gap between the core and the shell is reduced, and ferrimagnetic magnetite-like crystallites are enlarged and more populated. Paramagnetic wuestite-like crystalline phases are decreased substantially or disappeared completely. These enhanced morphology and crystalline characteristics make great contributions to improve magnetization performances significantly. Overall, this study provides the well-controlled synthetic schemes and morphology/crystalline structure details that are essential for better applications of iron oxide nanoparticles in various advanced fields including biomedicine and nanotechnology.

An asymmetric nine-arm star polymer, (polystyrene)

A series of silica nanoparticles (SNP-1, SNP-2, SNP-3, SNP-4, SNP-5 and SNP-6) were synthesized in ethanol by the hydrolysis and polycondensation reaction of tetraethoxysilane with the aids of water initiator and ammonia catalyst and then investigated in a comprehensive manner in terms of morphological structure by using synchrotron transmission small-angle X-ray scattering and grazing incidence wide-angle X-ray scattering and combined together with dynamic light scattering, scanning electron microscopy, infrared spectroscopy and thermogravimetry. They were confirmed to be successfully synthesized as oblate amorphous ellipsoids (Re = 9.70∼56.30 nm, equatorial radius; e = 0.78∼0.80, ellipsoidicity) with sharp surfaces in single unimodal and narrow size distributions. The radial density profile details, including two-phases (i.e., less dense core and denser shell), were determined for the first time, in addition to a set of structural parameter details (radius of gyration, radius, core radius, shell thickness, and radius distribution). Larger particle was synthesized conveniently by higher loading of ammonia solution with respect to the silane monomer. The as-synthesized silica particles were found to undergo two-step mass loss behaviors in heat treatment up to 500 °C; the first-step loss took place below 120 °C due to removals of physically absorbed water molecules and possible solvent residues and the second-step loss above 180 °C occurred by removals of water and ethanol byproducts due to the post condensation reactions of hydroxy and ethoxy residues.

This study delivers the first report on a cell-membrane-mimicking polymer system, poly[oxy(4-(13-cholenoatenonyl)-1,2,3-triazoyl-1-methyl)ethylene

A series of cyclic poly(e-caprolactone)s (c-PCLs) with extremely high purity have been prepared and quantitatively investigated in terms of the impact of molecular topology on the nanoscale film morphological structure. Quantitative synchrotron grazing incidence small angle X-ray scattering analysis found that c-PCLs, in comparison with their linear counterparts (l-PCLs), exclusively form a horizontal lamellar structure with a shorter long period, characterized by a thicker crystalline layer, thicker and denser interfacial layers and a thinner amorphous layer. Grazing incidence wide angle scattering analysis additionally confirmed higher crystallinities for c-PCLs, which were further supported by synchrotron X-ray reflectivity analysis. Overall, the quantitative structural analyses of this study provide for the first time comprehensive insights into cyclic topology effects on the nanoscale film morphology of biocompatible and environment-friendly PCL.

In this study, poly(δ-valerolactone) (PVL) axles bearing movable and ionically fixed rotaxane wheels linked with polystyrene (rot-PS-M and rot-PS-F) have been investigated for the first time in the...

In this study, we report for the first time the thin film morphology and property characteristics of a series of adamantane-containing polymers, which were investigated by using synchrotron grazing incidence X-ray scattering, X-ray reflectivity and spectroscopic ellipsometry. The chemically incorporated monomeric and dimeric adamantane units could disturb regular chain packing, ultimately producing amorphous polymers. They further tend to randomize chain orientations even in nanoscale thin films; surprisingly, random chain orientations could be achieved even for thermally-annealed thin films, which are quite different from the in-plane orientations of conventional polymer films being enhanced by thermal annealing. As a result, isotropic optical refractive indices and dielectric constants could be demonstrated even in nanoscale thin films, which are highly demanded for the production of advanced microelectronic devices. Moreover, the adamantane units incorporated into the backbone and as primary side groups could significantly reduce the dielectric constant, refractive index, critical angle, electron density and mass density of polymer. Overall, the positive impacts of incorporated adamantane units are huge on the polymer morphology and properties. All adamantane-containing polymers of this study are suitable materials for advanced microelectronics, which can replace current workhorse dielectrics, such as silicon oxide, silicon nitride, and polyimides, being used in microelectronic devices.

Bacillus licheniformis α-amylase (BLA) in a biomimetic buffer and extrinsic solutions (various pH values, temperatures, and metal ions) has been investigated for the first time in the view of three-dimensional (3D) structure by synchrotron X-ray and dynamic light scattering analyses. BLA in buffer is determined to have a structure resembling its crystallographic structure; but the 3D structure is slightly larger than the crystal structure. Such a structure is maintained with little variations in extrinsic solutions of pH 4.0–9.7, temperature 4–55 °C, and metal ions such as Ba2+, Mg2+, and Li+. These results collectively inform that BLA tends to favorably form a stable monomeric structure, which could provide structural clues to its enzymatic activities in moderate levels. Interestingly, BLA is found to reveal highly expanded structures at 65–75 °C and in Co2+ solution, which could correlate to the significantly pronounced enzymatic activities. However, BLA shows somewhat shrunken structures at pH 3.0 and in Hg2+ solution, supporting for the suppressed activities under these conditions.

Star-shaped polymers are very attractive because of their potential application ability in various technological areas due to their unique molecular topology. Thus, information on the molecular structure and chain characteristics of star polymers is essential for gaining insights into their properties and finding better applications. In this study, we report molecular structure details and chain characteristics of 17-armed polystyrenes in various molecular weights: 17-Arm(2k)-PS, 17-Arm(6k)-PS, 17-Arm(10k)-PS, and 17-Arm(20k)-PS. Quantitative X-ray scattering analysis using synchrotron radiation sources was conducted for this series of star polymers in two different solvents (cyclohexane and tetrahydrofuran), providing a comprehensive set of three-dimensional structure parameters, including radial density profiles and chain characteristics. Some of the structural parameters were crosschecked by qualitative scattering analysis and dynamic light scattering. They all were found to have ellipsoidal shapes consisting of a core and a fuzzy shell, such ellipse nature is originated from the dendritic core. In particular, the fraction of the fuzzy shell part enabling to store desired chemicals or agents was confirmed to be exceptionally high in cyclohexane, ranging from 74 to 81%, higher-molecular-weight star polymer gives a larger fraction of the fuzzy shell. The largest fraction (81%) of the fuzzy shell was significantly reduced to 52% in tetrahydrofuran, in contrast, the lowest fraction (19%) of core was increased to 48%. These selective shell contraction and core expansion can be useful as a key mechanism in various applications. Overall, the 17-armed polystyrenes of this study are suitable for applications in various technological fields including smart deliveries of drugs, genes, biomedical imaging agents, and other desired chemicals.

Here we report a study of the polymer chain/nanocrystal ordering in thin films (nanolayers) of regioregular poly(3-hexylthiophene) (P3HT) and blends of P3HT with a soluble fullerene derivative. A detailed analysis has been made of two dimensional (2D) grazing incidence X-ray diffraction (GIXRD) measurements with synchrotron radiation. P3HT samples with three different levels of regioregularity (RR) were synthesized and used to investigate the influence of RR on the chain ordering in thin films. Blend films were also prepared to investigate the influence of fullerene molecule addition on chain ordering. For the analysis, one dimensional (1D) GIXRD patterns were extracted from the 2D images for varying azimuthal angles, allowing information to be obtained for chain ordering in both the out-of-plane (OOP) and in-plane (IP) directions. These results show that the degree of P3HT chain ordering is strongly affected by RR, and that thermal annealing improves chain ordering in the OOP direction. This observation is in good agreement with high resolution transmission electron microscope measurements of film nanomorphology.

A series of polystyrene nanoparticles (PS-1, PS-2, PS-3, and PS-4) in aqueous solutions were investigated in terms of morphological structure, size, and size distribution. Synchrotron small-angle X-ray scattering analysis (SAXS) was carried out, providing morphology details, size and size distribution on the particles. PS-1, PS-2, and PS-3 were confirmed to behave two-phase (core and shell) spherical shapes, whereas PS-4 exhibited a single-phase spherical shape. They all revealed very narrow unimodal size distributions. The structural parameter details including radial density profile were determined. In addition, the presence of surfactant molecules and their assemblies were detected for all particle solutions, which could originate from their surfactant-assisted emulsion polymerizations. In addition, dynamic light scattering (DLS) analysis was performed, finding only meaningful hydrodynamic size and intensity-weighted mean size information on the individual PS solutions because of the particles&rsquo, spherical nature. In contrast, the size distributions were extracted unrealistically too broad, and the volume- and number-weighted mean sizes were too small, therefore inappropriate to describe the particle systems. Furthermore, the DLS analysis could not detect completely the surfactant and their assemblies present in the particle solutions. Overall, the quantitative SAXS analysis confirmed that the individual PS particle systems were successfully prepared with spherical shape in a very narrow unimodal size distribution.

This study reports the first structure and morphology details of octakis(acryloyloxypropyl)-octasilsesquioxane (POSS-Acryl8), a reactive inorganic-organic hybrid molecule, before and after photochemically crosslinked. POSS-Acryl8 was confirmed as an oblate ellipsoidal nanoparticle consisting of inorganic cage core (0.774 nm diameter) and chemically-bonded organic shell (1.447 nm thickness). The core volume fraction is only 0.95% in a single molecule, but drastically increases up to 18.8% in the neat bulk state and 31.9% in the photocured film state; the individual inorganic cores are eventually encapsulated with the networked shells (0.176 nm thickness) chemically interconnected with the neighbors. Based on such the highly networked structure and inorganic core reinforcement, the photocured POSS-Acryl8 exhibited exceptionally high optical transparency, glass transition temperature, surface hardness, and abrasion resistances. Due to the superior properties, clear hard POSS-Acryl8 coatings solved completely inherently poor surface hardness and abrasion resistances of conventional polymer window substrates and, furthermore, serious drawbacks in the eraser and steel wool abrasion resistances of glass window substrate. In addition, POSS-Acryl8 was found miscible with pentaerythritolylethyl tetraacrylate (PEEO-Acryl4) and thereby enhanced substantially the surface hardness and abrasion resistances of PEEO-Acryl4 through nanocomposite network formations. It turns out that the photocurable inorganic-organic POSS-Acryl8 hybrid and its composites with fully organic PEEO-Acryl4 are so suitable for optically clear hard top coating applications in advanced telecommunication, defense, automobile, and smart home appliance (smart and foldable phones, display devices, sensor windows, etc.).

Soluble aromatic polyimides and polyvinyls were prepared by incorporating pyridine moiety and its derivatives in the backbone and the side groups, respectively: 6F-Py-i polymers based on the polyimide backbone (6F-Py-1 to 6F-Py-7) and PVPy-i polymers based on the polyvinyl backbone (PVPy-1 to PVPy-4). All polymers were found to be amorphous. The 6F-Py-i polymers were thermally stable up to 511–545 °C; the PVPy-i polymers were stable up to 362–376 °C. Their glass transitions, thin film densities, molecular orbitals, and band gaps were determined. The electrical devices fabricated with the polymers in an electrode/polymer/electrode structure revealed p-type unipolar write-once-read-many times (namely, permanent) or dynamic random access memory or dielectric behavior, depending on the substituents of the pyridine unit and the film thicknesses. In particular, such digital memory characteristics were found to originate from the pyridine moieties possessing a high charge affinity in the polymers. However, the pyridine moieties were found to still need at least two or more aromatic substituents to get enough power to stabilize charges via utilizing the resonance effects provided by the substituents. Overall, this study demonstrated that the pyridine unit conjugated with two or more aromatic substituents is a very useful component to design and synthesize digital memory materials based on thermally stable polyimides and other high performance polymers. The 6F-Py-i polymers have potential for the low-cost mass production of high-performance programmable unipolar permanent memory devices with very low power consumption.

Pneumolysin (PLY) and its truncated fragments, domains 1–3 (D1–3), and domain 4 (D4), were purified as recombinant proteins after being cloned and over-expressed in Escherichia coli. The three-dimensional structures of these proteins were quantitatively investigated in a biomimetic condition, phosphate buffered saline (PBS) by synchrotron X-ray scattering. X-ray scattering analysis revealed important structural features including structural parameters. PLY was present as a monomeric form in PBS. The monomeric form resembled its crystallographic structure with a discrepancy of only 6.3%, confirming that PLY forms a stable structure and, thus, retains its structure in the crystalline state and even in PBS solution. D4 was also present as a monomeric form, but its structure was very different from that of the corresponding part in the crystallographic PLY structure; the discrepancy was 92.0%. Such a dissimilar structure might originate from a less folded-chain conformation. This result suggested that the structure of D4 is highly dependent on the crystalline or solution state and further on the presence or absence of the D1–3 unit. In contrast, D1–3 was dimeric rather than monomeric. Its structure was close to the most probable dimeric form of the corresponding part in the crystallographic PLY structure with 13.1% discrepancy. This fact indicated that the D1–3 unit forms a stable structure and, indeed, such structure is well maintained in the crystalline state as well as in PBS although presented as a dimer. This result further supported that the whole structural stability of PLY is mainly attributed to the structure of D1–3. All of PLY, D1–3, and D4 revealed aggregation tendencies during purification and storage. Overall, the structural characteristics of PLY and its domains in PBS may correlate to the PLY oligomer formation yielding large pore structures for the penetration of cell membranes.

A series of brush block copolymers (BBCPs) consisting of poly(decyl glycidyl ether) (PDGE) and poly(10-hydroxyldecyl glycidyl ether) (PHDGE) blocks, having four different types of chain tacticities, i.e., [at-PDGE]-b-[at-PDEGE], [at-PDGE]-b-[it-PDEGE], [it-PDGE]-b-[at-PDEGE], and [it-PDGE]-b-[it-PDEGE], where the it and at represent the isotactic and atactic chains, respectively, were prepared by t-Bu-P4-catalyzed sequential anionic ring-opening polymerization of glycidyl ethers followed by side-chain modification. The corresponding homopolymers, i.e., at-PDGE, it-PDGE, at-PHDGE, and it-PHDGE, were also prepared for comparison with the BBCPs. The PDGE homopolymers were significantly promoted in the phase transitions and morphological structure formation by the isotacticity formation. In particular, it-PDGE was found to form only a horizontal multibilayer structure with a monoclinic lattice in thin films, which was driven by the bristles’ self-assembling ability and enhanced by the isotacticity. However, t...

Three triple bond-conjugated naphthalene diimide (NDI) copolymers, poly{[N,N′-bis(2-R1)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-[(2,5-bis(2-R2)-1,4-phenylene)bis(ethyn-2,1-diyl)]} (PNDIR1-R2), were synthesized via Sonogashira coupling polymerization with varying alkyl side chains at the nitrogen atoms of the imide ring and 2,5-positions of the 1,4-diethynylbenzene moiety. Considering their identical polymer backbone structures, the side chains were found to have a strong influence on the surface morphology/nanostructure, thus playing a critical role in charge-transporting properties of the three NDI-based copolymers. Among the polymers, the one with an octyldodecyl (OD) chain at the nitrogen atoms of imide ring and a hexadecyloxy (HO) chain at the 2,5-positions of 1,4-diethynylbenzene, P(NDIOD-HO), exhibited the highest electron mobility of 0.016 cm2 V–1 s–1, as compared to NDI-based copolymers with an ethylhexyl chain at the 2,5-positions of 1,4-diethynylbenzene. The enhanced charge mobility...

We have newly synthesized a series of well-defined brush polyethers bearing cholesterol (Chol) and phosphorylcholine (PC) moieties in various compositions which can mimic cell membrane. They were thermally stable up to at least 230 °C and soluble in common solvents, showing good solution processability. Excitingly, they all favorably self-assembled, forming multibilayer structures with 21 chain conformation; in comparison, the brush polyether bearing only PC-bristles formed orthorhombically packed cylinder (OPC) structure with 125 helical chain conformation. Such multibilayer structure formations could be driven by a strong self-assembling ability of the Chol-bristle in extended conformation; the multibilayer structure formation was further promoted by the presence of PC-bristles. The OPC structure formation could be driven by a lateral packing ability of the brush polymer chain in the helical confirmation resulted from the minimization of repulsive interactions in the neighbored zwitterionic PC-bristles....

This study reports for the first time the excellent nonvolatile and volatile digital memory characteristics of polymers bearing 2-pyrrolidone and succinimide moieties. A series of new polymers is synthesized from poly(ethylene-alt-maleic anhydride) and four alcohol derivatives with and without 2-pyrrolidone and succinimide moieties. All polymers, including polyvinylpyrrolidone, are found to be thermally stable up to 195 °C or higher, and characterized regarding their molecular orbital energy levels, bandgap, and resistive digital memory behaviors. Excitingly, the polymers bearing either 2-pyrrolidone or succinimide moiety demonstrate p-type digital memory behaviors with high ON/OFF current ratios and long reliabilities. Nonvolatile digital memory performance is achieved over the film thickness range of 10-80 nm, whereas volatile digital memory is demonstrated over a much narrower range of film thickness. All digital memory performances can be originated from the 2-pyrrolidone and succinimide moieties possessing high affinity and stabilization power to charges via charge traps and transformations based on a hopping conduction process. Hence, these new polymers are suitable for the production of high-performance p-type nonvolatile and volatile digital memory devices. Moreover, 2-pyrrolidone and succinimide can be used as new and economical electroactive building blocks for the development of advanced digital memory materials.

A series of novel π-conjugated copolymers based on 2,2′-bis(1,3,4-thiadiazole) (BTDz) have been developed. Among them, the BTDz-based donor–acceptor alternating copolymer with the (E)-1,2-di(3-(2-ethylhexyl)thiophene)vinylene donor unit (PBTDzTV) exhibited a high solubility and high crystallinity. PBTDzTVs favorably self-assembled, forming face-on and edge-on multibilayer structures in thin nanoscale films. The relative volume fractions of these structures varied depending on the polymer’s molecular weight. The higher molecular weight polymer formed a higher volume fraction of the face-on structure; in particular, the polymer with a 26.6 kDa of number-average molecular weight made only the face-on structure. The device performance was improved as the polymer molecular weight and the volume fraction of the face-on structure increased. The bulk-heterojunction photovoltaic device based on PBTDzTV:PC71BM demonstrated the high power conversion efficiency (PCE) of 8.04% when the device was fabricated with the h...

We report the first digital nonvolatile memory devices fabricated with DNA and DNA-mimicking brush polymers. Salmon testes and calf thymus DNA devices, as well as DNA-mimicking brush polymer devices revealed p-type unipolar write-once-read-many-times memory behaviors with low switching-on voltage and high ON/OFF current ratio. Such permanent memory characteristics were confirmed to originate from the charge trapping and hopping nature of nucleobase moieties. Overall, this study demonstrated that DNA and DNA-mimicking polymers are good candidate materials for the production of p-type permanent memory devices with high performance, high stability and low power consumption.

Self-assembling characteristics of a series of amphiphilic zwitterionic brush random copolymers, poly(oxy(11-(3-sulfonylpropyltrimethylglycinyl)undecylesterthiomethyl)ethylene-co-oxy(n-do-decylthiomethyl)ethylene)s (PECH-DMAPSm where m is the mol% of DMAPS end group), were investigated at an air–water interface by using surface pressure–area isotherms, infrared spectroscopy, and X-ray reflectivity analysis. Interestingly the random polymers (m: 20–60 mol%) always formed Langmuir monolayer structures only rather than any other structures, regardless of the surface pressures. The Langmuir monolayers possessed enhanced lateral ordering together with conformational changes of the backbone and bristles through increasing the surface pressure. The monolayer structures were basically composed of a hydrophobic bristle phase in the air side and a hydrophilic backbone and bristle phase in the water side. The unique, highly ordered Langmuir monolayer structures could be realized by positive, cooperative efforts of several factors such as the compositional balance of hydrophobic and hydrophilic zwitterionic bristles, the air- and water-induced segregations of the bristles and backbone, the lateral ordering capabilities of the alkyl groups and the alkylenyl linkers in the bristles under the assistance of surface pressure, and the relatively strong anchoring power of DMAPS end groups in the water side using their high water affinity due to the hydrophilic zwitterionic nature. Overall, PECH-DMAPSm revealed a very unique self-assembling behavior at the air–water interface, always producing the Langmuir monolayer structure.

Polymer 105, 472-486(2016). doi:10.1016/j.polymer.2016.08.004, We investigated structural details and temperature-induced structural changes of an amorphouscrystallinebrush diblock copolymer, poly(3-((6-((7-(9H-carbazol-9-yl)heptanoyl)oxy)hexyl)thio)propyl glycidyl ether)60-b-poly(glycidyl 12-((3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyl)oxy)-12-oxododecanoate)20 (PGK60-PGF20) in nanoscale thin films using synchrotron grazing incidence X-ray scattering (GIXS) and Xrayphoton correlation spectroscopy (XPCS). Interestingly, the diblock copolymer was found toform a mixture of two different hexagonal cylinder structures (HEX1 and HEX2) where the PGFcylinders were aligned in the film plane. HEX1 was composed of PGF cylinders with higherpopulation of crystals while HEX2 consisted of PGF cylinders with lower population of crystals.Surprisingly, the PGF block chains favorably self-assembled because of strong lateral interactions inthe bristles, forming vertical multibilayer structure with partial interdigitation even in the highlyconfined cylindrical geometry. In heating run up to 340 K, some fraction of HEX2 was transformedto HEX1 via cold crystallization. In contrast, HEX1 was transformed to HEX2 above 340 K becauseof melting of the PGF crystals. The XPCS analysis found that the HEX structural changesassociated with the cold crystallization in the PGF cylinder domains took place with relatively fastdynamics. The HEX structural changes associated with melting of the PGF crystals in the cylinderdomains occurred with relatively slow dynamics; this unusual dynamics of structural changes mightbe attributed to a high energy melting process of PGF crystals against strong lateral interactions ofthe bristles., Published by Elsevier Science, Oxford

Amphiphilic poly(4-di(9,9-dihexylfluoren-2-yl)styrene)- b -poly(2-vinylpyridine)s (PStFl2 m - b -P2VP n ) in two different compositions and their homopolymers were synthesized: PStFl2 11 -b- P2VP 89 (50/50, volume ratio), PStFl2 12 -b- P2VP 33 (75/25), PStFl2, and P2VP. They were thermally stable up to around 350 °C. In nanoscale thin films, the diblock copolymers exhibited various phase-separated nanostructures depending on the composition and film process condition: random two phases, horizontal hexagonal P2VP cylinders, and hexagonally-close packed (HCP) P2VP spheres. Surprisingly, the hexagonal cylinder and HCP sphere structures are quite different from those of common diblock copolymers with similar compositions. The structural details of these thin film morphologies were investigated by synchrotron grazing incidence X-ray scattering. The thin film morphologies were found to make influences on the electrical memory performances of the polymers. In particular, the switching-ON voltage was influenced by the nanostructures and the film layer thickness as well as by the composition. Overall, the diblock copolymer films demonstrated excellent p -type permanent digital memory behaviors with unipolarity, long retention time, high ON/OFF current ratio and low power consumption. These memory behaviors were governed by a trap-limited space charge limited conduction mechanism combined with ohmic conduction and a hopping process.

Two series of crystalline–amorphous brush diblock copolymers bearing electroactive moieties were newly synthesized by sequential anionic ring-opening copolymerizations of glycidyl derivatives and subsequent selective postfunctionalizations; their homopolymers and analogues were additionally synthesized. Self-assembly structural details and electrical memory behaviors of these polymers in nanoscale thin films were investigated. The diblock copolymers revealed complex hierarchical self-assembly structures depending on the compositions. The self-assembly structure and orientation of the crystalline block chains were severely affected by the geometrical confinement (i.e., size and shape) stemming from microphase separation. Such film morphologies were found to significantly influence the electrical properties; they exhibited electrical properties from p-type permanent memory behavior to dielectric-like behavior. The memory behaviors were governed by the trap-limited space charge limited conduction mechanism c...

Poly(oxy(11-(biotinyl)undecylthiomethyl)ethylene-co-oxy(11-phosphoryl-cholineundecylthiomethyl)ethylene)s (PECH-BTmPCn: m = 0-100 mol % biotin (BT)-containing bristle; n = 100-0 mol % phosphorylcholine (PC)-containing bristle) were newly synthesized. All polymers exhibited excellent solution processability. They favorably self-assembled horizontal multibilayer structures in thin films with BT- and PC-enriched surfaces, which were driven by the lateral ordering of the fully extended upright bristles and the partial interdigitation between the BT and PC end groups of the bristles. Both hydrophilicity and water sorption of the films increased with the PC content. The PECH-BT100 films revealed remarkably distinctive sensitivity, selectivity, and adsorption ability for avidin against other proteins. Such remarkable performance was further significantly enhanced on the PECH-BTmPCn films in which PC moieties were incorporated to the BT-rich surface; in particular, the PECH-BT75PC25 films demonstrated the highest performance. Overall, the self-assembly brush copolymers of this study are very suitable for use in the high performance detection, adsorption, and separation of proteins and receptors, including avidin, which can reveal high affinity and selectivity to BT moiety.

In this study, synchrotron X-ray scattering and quantitative data analysis were performed on a series of 33-armed polystyrenes with four different arm molecular weights in cyclohexane (CHX, Θ solvent) and tetrahydrofuran (THF, good solvent). The quantitative scattering analysis was successfully done, providing molecular structure details and their responses to the solvent change. Each star system is confirmed to be prepared in a very narrow unimodal size distribution; the distribution is slightly broadened with increasing the arm molecular weight. It has an oblate ellipsoid shape, which is composed of two phases, a denser and smaller core and a less dense and thicker fuzzy shell; the ellipsoidicity ranges in 0.56–0.62. The core and shell phases are enlarged and thickened respectively by the arm molecular weight increases. Both the phases are further expanded in THF. Interestingly, the THF-induced expansion is predominant in the core against the fuzzy shell with a Gaussian like density gradient. Overall, the 33-armed star polystyrenes in various molecular weights are quite unique in the structural details and performance in solvent changes, which would be beneficial for advanced applications in various technological areas including smart deliveries of desired molecules (drug, gene, imaging agent, etc.).

Self-healing materials can partially or completely heal the damage done to them, and it is expected that their original function will be thereby restored. Herein, we report a novel self-healing polyvinyl (Sh-PV) containing functional polymer that reacts to thermal and ultraviolet (UV) energy. The structure of Sh-PV was characterized by fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (1H NMR). In addition, aluminum oxide (Al2O3) inorganic nanoparticles (NPs) were added and hybridized to improve their poor self-healing efficiency and surface hardness of the coated thin film. Mechanical nanoscratch testing and scanning probe microscopy (SPM) imaging of surface using a nanoindenter were performed to investigate the healing ability of self-healing thin films. The organic–inorganic hybrid self-healing polymer thin film exhibited a 10 % improvement in surface hardness as well as 100 % healing against nanoscale damage compared to virgin self-healing polymers. Here, we discuss and evaluate the optimized method and mechanism of the self-healing system based on the results of self-healing materials and physical recovery methods for healing surface damage.

A series of cyclic and linear poly (e-caprolactone)s (c-PCLs: c-PCLn, n = 30–200, average degree of polymerization; l-PCLs: l-PCLn, n = 30–200) in extremely high purity have been quantitatively investigated in terms of melt density, equilibrium melting temperature crystallization nature in connection to molecular topology effects. Synchrotron X-ray reflectivity analysis determined higher melt densities for c-PCLs than those of the linear counterparts. c-PCL was determined to exhibit 8.4 °C higher equilibrium melting temperature than that of the linear counterpart. Such higher equilibrium melting temperature may originate from a cooperative effort of thermodynamic factors (larger equilibrium heat of fusion and smaller equilibrium entropy) and morphological factors (thicker crystalline layer and higher fold surface energy). Comparing with l-PCL, c-PCL revealed apparently faster crystallization behavior at a chosen Tc but slower crystallization behavior at a same degree of supercooling because of the higher equilibrium melting temperature. Both c-PCL and linear counterpart were observed to follow heterogeneous nucleation and growth mechanism in crystallizations. Overall, this study achieved comprehensive insights into cyclic topology effects on the melt density, equilibrium temperature, and crystallization behavior of PCL.

Micelles were prepared in organic solvents by using three topological polymer amphiphiles: (i) cyclic poly(n-decyl glycidyl ether-block-2-(2-(2-methoxyethoxy)ethoxy)ethyl glycidyl ether) (c-PDGE-b-PTEGGE) and (ii) its linear analogue (l-PDGE-b-PTEGGE), (iii) linear poly(6-phosphorylcholinehexylthiopropyl glycidyl ether-block-n-dodecanoyl glycidyl ether) (l-PPCGE-b-PDDGE). For the individual micelle solutions, the size and distribution were determined by dynamic light scattering (DLS) and synchrotron X-ray scattering analyses. The synchrotron X-ray scattering analysis further found that c-PDGE-b-PTEGGE forms oblate ellipsoidal micelle in an ethanol/water mixture, l-PDGE-b-PTEGGE makes prolate ellipsoidal micelle in an ethanol/water mixture, and l-PPCGE-b-PDDGE forms cylindrical micelle in chloroform. This comparative study found that there are large differences in the size and distribution results extracted by DLS and X-ray scattering analyses. All possible factors to cause such large differences are discussed. Moreover, a better use of the DLS instrument with keeping its merits is proposed.

Cyclic PCL (c-PCL) has drawn great attention from academia and industry because of its unique, unusual structure and property characteristics due to the absence of end groups in addition to the biocompatibility and biodegradability of its linear analogue. As a result of much research effort, several synthetic methods have been developed to produce c-PCLs so far. Their chain, morphology and property characteristics were investigated even though carried out on a very limited basis. This feature article reviews the research progress made in the synthesis, morphology, and properties of c-PCL; all results and their pros and cons are discussed in terms of purity and molecular weight distribution in addition to the cyclic topology effect. In addition, we attempted to synthesize a series of c-PCL products of high purity by using intramolecular azido-alkynyl click cyclization chemistry and subsequent precise and controlled separation and purification; and their thermal degradation and phase transitions were investigated in terms of the cyclic topology effect.

Block copolymers of poly(2-vinyl-9-phenylcarbazole) (PVPK) and poly(2-vinylpyridine) (P2VP) or quaternized P2VP (QP2VP), including homopolymers, were synthesized by sequential living anionic polymerization and selective post-modification: PVPK–P2VP (43/57 in volume) and PVPK–QP2VP (31/69). All polymers were amorphous and soluble in common solvents. The blocks in the copolymers were found to undergo phase-separation. Nanoscale thin film morphology details were investigated by quantitative synchrotron grazing incidence X-ray scattering (GIXS) analysis. PVPK–QP2VP (31/69) self-assembled as a vertical lamellar structure in the carbon disulfide-annealed films, exhibiting p-type unipolar write-once-read-many-times (WORM) memory behavior. In comparison, PVPK–P2VP (43/57) formed a horizontal lamellar structure in chloroform-annealed films, revealing p-type unipolar dynamic random access memory (DRAM) behavior. Both the memory systems showed very high ON/OFF current ratio, 104–109, depending on the reading voltage. The switching-ON voltage, however, was lower for the PVPK–QP2VP (31/69) film (ca. 4 V) than for the PVPK–P2VP (43/57) (ca. 6 V). Overall, WORM memory and DRAM behaviors were nicely demonstrated with high performances by the development of well-defined lamellar structure in the block copolymer films and their memory modes could be easily tuned from one to another or vice versa by the orientation control of the lamellar structure. Moreover, the excellent memory performance results based on the vertical lamellar structure open up a process feature, that digital memory devices can be significantly improved in terms of their memory capacity by the fabrication of a nanoscale vertical lamellar structure using block copolymers composed of electroactive and dielectric blocks. In addition, memory origins and mechanisms in the block copolymer films were investigated.

Self-assembly characteristics of poly(oxy(11-phosphorylcholineundecylthiomethyl)ethylene) (PECH-C11-PC), a lipid-mimicking brush polymer, were investigated for the first time in nanoscale thin films as well as at the air–water interface using synchrotron grazing incidence X-ray scattering, X-ray reflectivity, and infrared spectroscopy. In thin films, the PECH-C11-PC molecules were found to form a well-ordered, in-plane-oriented molecular multibilayer structure in which the bristles made partial interdigitation in the neighbored layers via the favorable interactions of the PC end groups. The brush polymer molecules were further found to favorably form molecular assemblies at the water interface. They initially formed a monolayer assembly in which the hydrophilic backbones were in the extended conformation and the zwitterionic PC ends were anchored at the water interface and the hydrophobic alkylenyl linkers were present over the water surface. This phase underwent a surface pressure-driven structural transformation path way, ultimately forming a canonical bilayer structure similar to that commonly observed among natural lipids. These remarkable self-assembly behaviors were comprehended with consideration of the hydrophilic backbone, zwitterionic PC end, hydrophobic alkylenyl linker, and their selective interactions.

Two series of crystalline–crystalline miktoarm star polymers were prepared and their thin film morphologies were investigated in detail by synchrotron grazing incidence X-ray scattering (GIXS): poly(n-hexyl isocyanate)(5000)–poly(e-caprolactone)1–3(17000) (PHIC(5k)–PCL1–3(17k)) and poly(n-hexyl isocyanate)(10000)–poly(e-caprolactone)1–3(10000) (PHIC(10k)–PCL1–3(10k)). In addition, their thermal properties were examined. All miktoarm star polymers revealed a two-step thermal degradation behavior where the PHIC arm was degraded first, followed by the PCL arm underwent degradation. Interestingly, all miktoarms were found to show a highly enhanced thermal stability, regardless of their molecular weight over 3k to 17k, which might be attributed to their one-end group capped with the counterpart arm(s) via arm-joint formation. Surprisingly, all miktoarm star polymers always developed only lamellar structure in toluene- and chloroform-annealed films via phase-separation, regardless of the length of PHIC arm as w...

We synthesized chemically well-defined brush (i.e., comb-like) polymers bearing guanine, cytosine, uracil, or thymine moieties at the bristle ends. The polymers were stable up to 220 °C and were readily solution-processable, yielding high-quality films. Interestingly, the brush polymers favorably self-assembled to form molecular multibilayer structures stabilized by hydrogen bonding interactions among the nucleobase moieties at the bristle ends, which provided nucleobase-rich surfaces. The multibilayer-structured polymer films showed high water affinity. They also displayed selective protein adsorption, suppressed bacterial adherence, facilitated cell adhesion, and exhibited good biocompatibility in mice. The brush polymer DNA-mimicking comb-like polymers are suitable as biomaterials and in protein separation applications. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 1151–1160

As integrated microelectronic circuit device dimensions continue to shrink, low dielectric constant (low-k) interlayer dielectrics are required for minimizing RC signal delay, capacitive coupling noise, and power consumption. The implementation of low-k materials in an interconnected structure, however, is known to be a very difficult task because of many criteria imposed by the structural functionality and the integration process. Here, we report structural reliability evaluation for the integration of low-k nanoporous organosillicate dielectrics into a multilayer structure, involving capping, chemical mechanical polishing (CMP), post-CMP cleaning, and thermal annealing processes. We have successfully investigated the structural reliability of the low-k dielectric layer subjected to such harsh processes using synchrotron grazing incidence X-ray scattering and reflectivity (GIXS and XR) analyses. This study additionally demonstrated that synchrotron GIXS and XR techniques are very powerful tools for providing valuable, accurate insight into the nanopore structure in low-k dielectric thin layers and the structural changes with the integration process conditions.

Here we report that poly(N-dodecyl-2-ethynylpyridiniumbromide) (PDEPB) interlayers between electron-collecting zinc oxide (ZnO) layers and bulk heterojunction (BHJ) layers act as a universal interfacial layer for improving the performances of inverted-type polymer:fullerene solar cells. Three different BHJ layers, poly(3-hexylthiophene) (P3HT):[6,6]-phenyl-C 61 -butyric acid methyl ester (PC 61 BM), poly[(4,8-bis(2-ethylhexyloxy)-benzo[1,2-b:4,5-b']dithiophene)-2,6-diyl-alt-(N-2-ethylhexylthieno[3,4- c ]pyrrole-4,6-dione)-2,6-diyl]] (PBDTTPD):PC 61 BM, and poly[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4- b ]-thiophenediyl] (PTB7) and [6,6]-phenyl-C 71 -butyric acid methyl ester (PC 71 BM), were employed so as to prove the role of the PDEPB interlayers. Results showed that the power conversion efficiency (PCE) of polymer:fullerene solar cells with the three different BHJ layers increased in the presence of the PDEPB interlayers prepared from 0.5 mg/ml solutions. The improved PCE was attributed to the conformal coating of the PDEPB layers on the ZnO layers (by atomic force microscopy measurement), lowered work functions of ZnO induced by the PDEPB layers (by Kelvin probe measurement), and reduced interface resistance (by impedance spectroscopy measurement), as supported by the noticeable change in the atom environments of both the ZnO and PDEPB layers (by X-ray photoelectron spectroscopy measurement).

The mechanism behind electrical memory behavior of carbazole-containing polyimides (PIs) in nanoscale thin films was investigated. For this investigation, a series of poly(3,3'-dihydroxy-4,4'-biphenylene-co-3,3'-bis(N-ethylenyloxycarbazole)-4,4'-biphenylene hexafluoro-isopropylidenedi-phthalimide)s (6F-HAB-HABCZn PIs) with various compositions was synthesized as a model carbazole-containing polymer system. The thermal properties, band gaps, and molecular orbital levels of the PIs were determined. Furthermore, the chemical compositions, as well as the nanoscale thin film morphologies and electron densities, were analyzed, providing detailed information on the population and positional distribution of carbazole moieties in thin films of the PIs. PI Devices were fabricated with aluminum electrodes and tested electrically. The PI thin film layers in the devices exhibited electrically permanent memory behavior, which was driven by trap-limited space-charge limited conduction and ohmic conduction. The permanent memory characteristics were found to be attributed to the incorporated carbazole moieties rather than from the other chemical components. Furthermore, the memory characteristics depended significantly on the population and positional distribution of carbazole moieties in the PI layer, as well as the film thickness. Considering that the backbone is not conjugated, the present results collectively indicate that the electrical switching behavior of the PI films is driven by the carbazole moieties acting as charge traps and a hopping process using the carbazole charge-trap sites as stepping-stones.

Covalent incorporations into polymers of fullerene were achieved via the Cu(I)-catalyzed azide–alkyne click polymerizations of a fullerene derivative monomer functionalized with 5-(trimethylsilyl)pent-4-yn-1-yl groups and a comonomer functionalized with azidomethyl groups, producing the novel fullerene polymers P1-C60 and P2-C60. Despite their extremely high fullerene loading levels, the polymers were soluble in common organic solvents and exhibited no aggregation of fullerene units in films. Moreover, devices containing these fullerene polymers were easily fabricated with common coating processes that exhibit excellent unipolar and bipolar flash memory characteristics as well as unipolar permanent memory characteristics, with high ON/OFF current ratios, long retention times, and low power consumption. These electrical switching behaviors were favorably operated by electron injection. Overall, these devices are the first n-type bipolar and unipolar digital polymer memory devices which can be operated in f...

Self-assembly characteristics of a well-defined brush polymer, poly(oxy(n-dodecyl-thiomethyl)ethylene) were in detail investigated at the air-water interface with surface–area isotherm, X-ray reflectivity, and infrared spectroscopy analyses. The brush polymer self-assembled at the air-water interface as a fully-extended chain via favorable lateral packing of the bristles in a fully extended conformation, forming highly ordered, oriented Langmuir monolayer. This well-ordered monolayer was produced via a five-regime structure formation with varying surface pressure. A Langmuir monolayer film with ≤1.92 nm thick was formed in the low surface pressure regime ≤18 mN/m and then converted to a highly dense, ordered monolayer with 3.65 nm thick in the high surface pressure regime ≥35 mN/m through monolayer-to-bilayer transition and bilayer-to-monolayer inversion. These Langmuir film formations and their ordering and orientation might be driven by the well-defined chemical architecture and the lateral orderings of the polymer backbones and the bristles in fully extended conformations.