Original Article in 2016

Interface manipulation to pursue unusual nanostructures was performed using a strategically designed triblock terpolymer with a short middle segment, poly(styrene-b-methyl methacrylate-b-2,2,2-trifluoroethyl methacrylate). A short middle segment of poly(methyl methacrylate) (PMMA) that does not form any distinct domains was found to play an important role in manipulating the interface between the polystyrene (PS) and poly(2,2,2-trifluoroethyl methacrylate) (PTFEMA) domains and forming unconventional partially continuous oblate cylinders with an oblique lattice, as confirmed by small angle X-ray scattering (SAXS) and dual-axis transmission electron microtomography (TEMT).

A series of poly(ethylene glycol) methyl ether methacrylate (PEGMA) hydrogels have been prepared. The smaller the monomer molecular weight, the higher the crosslinking degree, the lower the hydration. Protein adsorption and bacteria/blood cell attachment tests unveil that PEGMA₅₀₀ hydrogel presents a suitable structure to minimize biofouling. A higher molecular weight of monomers is associated to a higher hydrophilicity, but excess of free water facilitates foulant diffusion. Low molecular weight of monomer does not permit to achieve hydration level good enough to form a protective layer against fouling.

Autophobic dewetting of polymer melts was characterized by well-defined polystyrene (PS) melt droplets that dewetted chemically identical brushes upon thermal annealing. The contact angle (θ) of PS droplets on the brushes and interfacial tension (γ_m/b) between the PS melts and brushes significantly increased as the chain length of PS brushes decreased and grafting density increased. The super autophobicity of the PS melt at the extremely short and dense PS brush was evaluated when the γ_m/b increasingly converges on the maximum interfacial tension (γ*_m/b).

Three types of bottom surface layers (BSLs-A, B, C) with different surface properties and a top-coat (TC-A) were applied to investigate perpendicular orientation control of PMMA-b-PMAPOSS domains in the thin films with thermal annealing. The combination of BSL-A and TC-A yielded perpendicular cylinders after annealing at 180 °C for 60 min, whereas the other combinations produced parallel cylinders. Water contact angles and surface free energies (SFEs) of the BSLs were evaluated for the perpendicular orientation. It was found that the SFEs were more effectual indicators than the water contact angles.

We measured the single-molecule interaction force between various hydroxybenzoic acids and a Si₃N₄ cantilever by atomic force microscopy in force curve mode. The adhesion properties of hydroxybenzoic acids with different numbers of hydroxyl groups in various positions on the aromatic ring were compared to determine the effect of the hydroxyl groups on single-molecule interactions. It was found that as the number of hydroxyl group increases, the number of single-molecule interactions increases and the interaction force also increases. A catecholic system with two hydroxyl groups on the aromatic ring, similar to that found in mussel adhesive, has been well studied. Here we demonstrate that gallic acid with three hydroxyl groups on the aromatic ring showed good adhesion and a large number of single-molecule interactions. We synthesized gallic acid adhesives that exhibited sufficiently strong adhesion (10 MPa) to be of practical use.

In this study, we were synthesized novel biomass network polymer containing silsesquioxane as inorganic moiety. First, novel network polymer precursors were synthesized with castor oil or branched poly(l-lactic acid) (PLLA) and 3- (triethoxysilyl) propyl isocyanate. Precursors were carried out to cross-link reaction at 120 °C for 24 h, and obtained network polymer films. Furthermore, we were synthesized cross-linked film, which was increased inorganic moiety using tetraethyl orthosilicate.

1,1-Bis(4′-N,N-dimethylaniline)-tetraphenylsilole (APh-TPS) and APh-TPS containing polymers (PF-APh-TPS) were successfully synthesized and characterized. Compared with the 1,1-dimethyl-2,3,4,5-tetraphenylsilole analogs, superior PLED performances were achieved based on PF-APh-TPS with 1,3,5-tris (2-N-phenylbenzimidazolyl) benzene (TPBI) as the hole-blocking layer.

We demonstrated the controlled incorporation of Au nanoparticle grafted with polystyrene (PS) molecules in the helical microdomains of ABC-type linear triblock terpolymers composed of PS, polyisoprene (PI) and poly(methyl methacrylate) (PMMA). The Au nanoparticles grafted with three PSs with different molecular weights were synthesized and incorporated into the terpolymer films. The morphologies of composite films and localization of Au nanoparticles were three-dimensionally characterized with transmission electron microtomography observation. By varying the molecular weights of grafted PS molecules on Au nanoparticles, their assemblies were successfully controlled in the double-helical microdomains.

A series of n-type D–A terpolymers (P(NDI2HD-T-S)) with various thiophene (T) and selenophene (S) compositions (T/S=100/0, 80/20, 50/50, 20/80 and 0/100) was successfully synthesized. To understand the effects of the T/S ratios, we studied their influence on the optical, electrical and structural properties. The insertion of more S content in the polymer backbone induced the enhanced structural ordering and electron mobility. Therefore, the all-polymer solar cells based on PTB7:P(NDI2HD-T-S) blend had greatly improved efficiency as the S content increased.

A number of amphiphilic N-isopropylacrylamide (NIPAAm) oligomers and polymers with a S-1-dodecyl-S′-trithiocarbonate (DTC) and an amino terminal group has been designed. The electrostatic interactions between the amine segments and the anionic metal cyanide complexes have a significant role in the morphology and thermoresponsiveness of the hybrids. The hybrids of PNIPAAms and metal complexes can lead not only to nanostructures in water but also to cylindrical aggregates (or spherical aggregates) assembled in rod, square and sheet structures.

We prepared bisphenol A (BPA)-imprinted polypeptide gel layers by chemical cross-linking of β-cyclodextrin-modified poly(L-lysine) (CD-PLL) on quartz crystal microbalance (QCM) sensor chips and investigated their molecular recognition behaviors using QCM. This paper focuses on the preparation and molecular recognition capacity of the BPA-imprinted CD-PLL gel layers on QCM sensor chips with polyterthiophene film formed via electropolymerization.

Cross-linked nanocellular polymer films: water- and oil-repellent anti-reflection coating. We applied the block copolymer template assisted with supercritical carbon dioxide method to poly(methyl methacrylate-r-glycidylmethacrylate)-b-poly(perfluorooctylethyl methacrylate) (PMGMA-PFMA) to fabricate cross-linkable nanocellular thin films. The nanocellular thin films showed a very low refractive index, low reflection as an AR coating as well as good chemical robustness by chemical cross-linkage of the glycidyl groups. In addition, the film surface provides water- and oil-repellent properties due to hydrophobic and oleophobic fluorine-containing PFMA.

The poly(pentafluorophenyl acrylate) thin film provides a reactive surface platform through facile post-modification with primary alkyl amines. We report the effect of the most important parameters in this reaction, molecular weight of the reactive polymers and the aliphatic chain length of primary amines, on the degree of exchange of the thin films. The studies with neutron reflectivity and quartz crystal microbalance offer physical backgrounds for developing versatile functional thin films based on this chemistry, in terms of penetration and exchange kinetics as a function of molecular weight of reactive ester polymers and primary amines.

Surfaces of cyclo-olefin polymers (COP) are photoactivated by vacuum ultraviolet (VUV) light and can be bonded with a practical bonding strength at low temperatures below T_g. We investigated the mechanism of the low-temperature bonding of COP by nanofractography using high-resolution scanning electron microscopy. It was indicated that the interfaces were fractured via pull out of the polymer chains connected at the interface by hydrogen bonding.

We demonstrate that nonvolatile memory devices can be prepared using layer-by-layer-assembled nanocomposite films, and additionally that their memory performance can be easily enhanced by an additional insertion of charge trap elements (that is, graphene oxide nanosheets) within the films. These devices exhibited memory performance with a high ON/OFF current ratio of ~10⁴.

The orientation behavior and domain spacing relaxation of the phase-separated structure of poly(methyl methacrylate-b-n-butyl acrylate) thin films were investigated by grazing-incidence small-angle X-ray scattering (GISAXS). Moreover, low-energy GISAXS was performed for the in-depth profiling of the lamellar structure. The domain spacing (D_||) relaxation took longer than the orientation of the lamellae. Furthermore, the D_|| in the vicinity of the surface was greater than inside the film, which indicates that the D_|| near the surface relaxed faster than inside due to the higher mobility of the polymer chain.

Light scattering and viscosity measurements were carried out for thermally renatured xanthan samples with various molar masses and molar mass distributions. The increases in the molar mass, radius of gyration, and intrinsic viscosity of a xanthan sample with high molar mass and wide molar mass distribution upon renaturation were smaller than in xanthan samples with lower molar masses and narrower molar mass distributions. This behavior could be explained by the increase in “intra-dimer-renaturation” caused by the slower diffusion of xanthan with higher molar mass.

Nanostructured composite electrolyte films consisting of a cross-linked lyotropic liquid crystal monomer and varying amounts of an organic carbonate liquid electrolyte and a Li salt were systematically prepared and characterized for their ionic conductivity and ability to function as the separator membrane in a Li-metal/fluorinated carbon test cell. Films with a well-defined bicontinuous cubic phase were sufficiently strong to act as an ion-conductive separator and displayed stable open-circuit potentials, whereas the majority of the mixed-phase films gave shorted cells.

Thermal reaction mechanism of γ-irradiated polytetrafluoroethylene (PTFE) is elucidated at the molecular level by kinetic analysis, where a new multichannel Fourier-transform chemiluminescence spectrometer was used.

A polymer cross-linking system undergoes a phase transition from liquid to solid at a critical point, which is called the sol-gel transition. We independently tuned the intrinsic parameters governing the sol-gel transition, that is, the connectivity and polymer concentration, using a model gel system (tetra-polyethylene glycol gel), and examined the model predictions. The lattice-based percolation model can be applied only for systems prepared around the overlapping concentration. In the case far below the overlapping concentration, the aggregation model well reproduced the transition behavior.