Long-Range Ordered Crystallization Structure in the Micromolded Diblock Copolymer Thin Film

Confined crystallization of the micromolded poly­(butadiene)-<i>block</i>-poly­(ε-caprolactone) (PB-<i>b</i>-PCL) diblock copolymer thin film was studied in this work. The long-range regular ordering of the PCL crystal with crystallographic <i>b</i>-axis parallel to the long-axis of the channel was detected, as indicated by the electron diffraction and grazing-incidence X-ray diffraction experimental results. This preferential crystallographic orientation is mainly because that PCL block crystallization was readily influenced by the geometric effect, then, the fast-growth direction (crystallographic <i>b</i>-axis) was forced to extend along the long-axis of the channel to grow long. Moreover, the substrate induced ordering of the block copolymer restricted the “in-plane” molecular diffusion in the residual layer, and cross-channel crystallization was precluded. Hence, micromolding seems to be a promising method for tailoring the nanoscale crystallization of block copolymer in thin films

Additional file 1: of The Fabrication of Ordered Bulk Heterojunction Solar Cell by Nanoimprinting Lithography Method Using Patterned Silk Fibroin Mold at Room Temperature

The cross-section SEM images of layers within solar cell before (a) and after (b) the depositing of PCBM and LiF/Al layers on the top of P3HT nanograting film. The cross-section SEM images of layers within solar cell are shown to offer some relevant data about the thickness of each layer in the solar cell. (DOC 235 kb

Additional file 2: of The Fabrication of Nanoimprinted P3HT Nanograting by Patterned ETFE Mold at Room Temperature and Its Application for Solar Cell

One-dimensional GIWAXD curves in the q xy direction. Curves are integrated from Fig. 4a, b, c. Parallel and vertical are referred as measurements performed with nanograting line direction parallel and perpendicular to the direction of incident X-rays. It indicates that the (010) reflection signals of samples is present indeed in the q xy direction, which can be indicated by the one-dimensional integrated curve stem from the Fig. 4a, b, c. The peaks at q = 16.8 nm−1 refer to the (010) plane reflections of P3HT crystal and can be investigated for the three samples. (DOC 45 kb

Additional file 1: of The Fabrication of Nanoimprinted P3HT Nanograting by Patterned ETFE Mold at Room Temperature and Its Application for Solar Cell

The cross-section SEM image of P3HT nanograting film bearing a width of ~130 nm and a period of ~280 nm. According to the fabrication process of nanoimprinted P3HT nanograting film, the highest aspect ratio of P3HT nanograting obtained (bearing a width of ~130 nm and a period of ~280 nm) is about 0.5. Here, we define the aspect ratio is the ratio value of height (L) to width (W) within nanograting. (DOC 186 kb

Confinement Induced Preferential Orientation of Crystals and Enhancement of Properties in Ferroelectric Polymer Nanowires

The physical properties of polymers strongly depend on the molecular or supermolecular order and orientation. Here we demonstrate the preferential orientation of lamellar crystals and the enhancement of ferro/piezoelectric properties in individual poly­(vinylidene fluoride-<i>co</i>-trifluoroethylene) (P­(VDF-TrFE)) nanowires fabricated from anodic alumina oxide (AAO) templates. The crystallographic <i>a</i> axis of P­(VDF-TrFE) was found to be aligned along the long axis of nanowires due to geometrical confinement and grapho-expitaxial crystals growth. The alignment of lamellar crystals in P­(VDF-TrFE) nanowires and enhancement of crystallization translated into improved ferro/piezoelectric properties such as lower coercive field and higher piezoelectric coefficient, testified by piezoresponse force microscopy images and piezoresponse hysteresis loops

Structure and Ferroelectric Properties of Nanoimprinted Poly(vinylidene fluoride-<i>ran</i>-trifluoroethylene)

Nanoimprint lithography (NIL) was used to shape thin films of a ferroelectric copolymer of vinylidene fluoride and trifluoroethylene (PVDF-TRFE), using a variety of molding shapes and imprinting conditions. The morphology of the layers was characterized by atomic force microscopy (AFM), and preferential orientation of the crystallographic axes was monitored by infrared microspectroscopy; in addition, the local ferroelectric properties were obtained by piezoresponse force microscopy (PFM). When the sample is imprinted in its paraelectric phase in conditions leading to complete confinement, in cavities of size lower than the natural lamellar length observed in a continuous thin film, the crystallographic <i>a</i> axis aligns preferentially parallel to the substrate, and the crystalline lamellae are of significantly reduced length. These characteristics translate in a strongly decreased coercive field and accelerated ferroelectric switching, which is in part ascribed to the improved coupling between the electric field and the properly oriented dipole moments. When decreasing the confinement either by leaving a residual film connecting the nanopillars, or by increasing the lateral size of the nanopillars above the natural lamellar length, or by using line molds where confinement only exists in one direction, or by using continuous films, the preferential orientation becomes less visible and the lamellar length increases, resulting in increased coercive and switching fields. Interestingly, the average length of the crystalline lamellae tends to correlate with the value of the coercive field. Finally, if the sample is imprinted in the melt, a flat-on setting of the crystalline lamellae ensues, with a vertical chain axis which is unfavorable for ferroelectric properties probed with a vertical electric field

The Ferro- to Paraelectric Curie Transition of a Strongly Confined Ferroelectric Polymer

Nanopillars of ferroelectric polymers are of strong interest for the fabrication of low-cost nanoscale actuators and memories of high density. However, a limiting factor of polymers compared to inorganic ferroelectric materials is their low ferro- to paraelectric Curie transition, a problem compounded by the possible further decrease of the Curie temperature in nanostructures as was suggested by previous studies. Here we develop a methodology based on piezoresponse force microscopy to study the thermal stability of data stored in free-standing poled and annealed nanopillars of ferroelectric poly­(vinylidene fluoride-<i>ran</i>-trifluoroethylene), P­(VDF-TrFE), and thereby demonstrate that the Curie transition of a properly processed strongly confined ferroelectric polymer is not significantly modified compared to the bulk material, at least down to a mass as small as ca. 560 attograms corresponding to ca. 1500 chains only

Nanoscale Design of Multifunctional Organic Layers for Low-Power High-Density Memory Devices

We demonstrate the design of a multifunctional organic layer by the rational combination of nanosized regions of two functional polymers. Instead of relying on a spontaneous and random phase separation process or on the tedious synthesis of block copolymers, the method involves the nanomolding of a first component, followed by the filling of the resulting open spaces by a second component. We apply this methodology to fabricate organic nonvolatile memory diodes of high density. These are built by first creating a regular array of ferroelectric nanodots by nanoimprint lithography, followed by the filling of the trenches separating the ferroelectric nanodots with a semiconducting polymer. The modulation of the current in the semiconductor by the polarization state of the ferroelectric material is demonstrated both at the scale of a single semiconductor channel and in a microscopic device measuring about 80 000 channels in parallel, for voltages below <i>ca.</i> 2 V. The fabrication process, which combines synergetically orthogonal functional properties with a fine control over their spatial distribution, is thus demonstrated to be efficient over large areas