Grazing Incidence Wide-angle X-ray Diffraction Research Articles

New Insight into Nanoscale Identification of the Polar Axis Direction in Organic Ferroelectric Films.

Ferroelectric poly(vinylidene fluoride-co-trifluoroethylene) [P(VDF-co-TrFE)] thin films have been deposited by spin-coating onto the Bi0.5Na0.5TiO3(BNT)/LNO/SiO2/Si heterostructure. The copolymer microstructure investigated by using grazing-incidence wide-angle X-ray diffraction (GIWAXD) and deduced from the (200)/(110) reflections demonstrates that the b-axis in the P(VDF-co-TrFE) orthorhombic unit cell is either in the plane or out of the plane, depending on the face-on or on the two types of edge-on (called I and II) lamellar structures locally identified by atomic force microscopy (AFM). For edge-on I lamellae regions, the electroactivity (dzzeff ∼ -50.3 pm/V) is found to be twice as high as that measured for both edge-on II or face-on crystalline domains, as probed by piezoresponse force microscopy (PFM). This result is directly correlated to the direction of the ferroelectric polarization vector in the P(VDF-co-TrFE) orthorhombic cell: larger nanoscale piezoactivity is related to the b-axis which lies along the normal to the substrate plane in the case of the edge-on I domains. Here, the ability to thoroughly gain access to the as-grown polar axis direction within the edge-on crystal lamellae of the ferroelectric organic layers is evidenced by combining the nanometric resolution of the PFM technique with a statistical approach based on its spectroscopic tool. By the gathering of information at the nanoscale, two orientations for the polar b-axis are identified in edge-on lamellar structures. These findings contribute to a better understanding of the structure-property relationships in P(VDF-co-TrFE) films, which is a key issue for the design of future advanced organic electronic devices.

Polymer-Gated Transistors with Only One Solution-Processed, Single Crystalline Organic Microwire for Light and Oxygen Detection.

Organic semiconductors employed in single crystalline form have several advantages over polycrystalline films, such as higher charge carrier mobility and better environmental stability. Herein, we report the fabrication and characterization of a solution-processed microsized single-crystalline organic wire of n-type N,N'-dipentyl-3,4,9,10-perylene tetracarboxylic diimide (PTCDI-C5). The crystal was applied as an active layer in polymer-gated organic field-effect transistors (OFETs) and organic complementary inverter circuits. The single crystaiiline nature of PTCDI-C5 wires were characterized using two-dimensional grazing incidence wide-angle X-ray diffraction (2D-GIXD) and polarized optical microscopy. OFETs with the PTCDI-C5 crystals exhibited high n-type performance and air stability under ambient conditions. To investigate the electrical properties of the single-crystalline PTCDI-C5 wire more precisely, OFETs with only one PTCDI-C5 microwire in the channel were fabricated, and clear n-type characteristics with satisfactory saturation behavior were observed. The device with only one crystal wire exhibited characteristics with significantly lower variation compared to the multicrystal devices, which shows that the density of crystal wires is a critical factor in precisely investigating device performance. The devices exhibited a reversible threshold voltage shift under vacuum and oxygen conditions, without changing the charge carrier mobility. Light-sensitive characteristics were also observed. Additionally, this solution-processed, highly crystalline organic semiconductor can be used in high-performance organic electronic circuits as well as in gas or light sensors.

Controlled growth of perovskite layers with volatile alkylammonium chlorides.

Controlling the crystallinity and surface morphology of perovskite layers by methods such as solvent engineering1,2 and methylammonium chloride addition3-7 is an effective strategy for achieving high-efficiency perovskite solar cells. In particular, it is essential to deposit α-formamidinium lead iodide (FAPbI3) perovskite thin films with few defects due to their excellent crystallinity and large grain size. Here we report the controlled crystallization of perovskite thin films with the combination of alkylammonium chlorides (RACl) added to FAPbI3. The δ-phase to α-phase transition of FAPbI3 and the crystallization process and surface morphology of the perovskite thin films coated with RACl under various conditions were investigated through in situ grazing-incidence wide-angle X-ray diffraction and scanning electron microscopy. RACl added to the precursor solution was believed to be easily volatilized during coating and annealing owing to dissociation into RA0 and HCl with deprotonation of RA+ induced by RA⋯H+-Cl- binding to PbI2 in FAPbI3. Thus, the type and amount of RACl determined the δ-phase to α-phase transition rate, crystallinity, preferred orientation and surface morphology of the final α-FAPbI3. The resulting perovskite thin layers facilitated the fabrication of perovskite solar cells with a power-conversion efficiency of 26.08% (certified 25.73%) under standard illumination.

Fluorinated Benzothiadiazole-based polymers with chalcogenophenes for organic field-effect transistors

The effect of incorporating chalcogenophene comonomers, namely, furan, thiophene, and selenophene, on the optoelectrical properties of cyclopentadithiophene-based polymers (P1, P2, and P3, respectively) for organic field-effect transistors is reported. The optical, electrical, and morphological properties of the P1, P2, and P3 are investigated. Compared to the other polymers, the P2 showed the highest crystallinity with the shortest π–π stacking distance ( d π–π ≈ 3.58 Å) and the longest crystalline length ( L c ≈ 40 Å), as confirmed by two-dimensional grazing incidence wide-angle X-ray diffraction. However, P3 had the highest hole mobility ( μ = 0.25 cm 2 /V-s), which is higher than P1 ( μ = 0.06 cm 2 /V-s) and P2 ( μ = 0.20 cm 2 /V-s). The relatively lower mobility of the P2 than of the P3 is attributed to its island-like crystalline domains, confirmed by atomic force microscopy results and the edge-on dominant orientation. Our findings suggest a new design guideline for developing high-mobility π-conjugated polymers. • We first address the importance of size of substituted atoms in determining optoelectronic properties and thin film crystallinity of the FBT-based polymers. • The influence of chalcogenophene atom substitution on optoelectrical properties of the FBT-based polymers was thorough investigated. • Combining a highly-crystallized molecular packing with effective morphologies led to the best hole mobilities of 0.25 cm 2 V −1 s −1 for P3.

A Highly Conductive n-Type Coordination Complex with Thieno[3,2-b]thiophene Units: Facile Synthesis, Orientation, and Thermoelectric Properties.

An organometallic nickel complex containing thieno[3,2-b]thiophene units was designed and synthesized. Composite films of the resulting nickel complex and polyvinylidene difluoride, which can be fabricated via a simple solution process under atmospheric conditions, exhibit remarkably high n-type conductivity (>200 S cm-1). Moreover, the thermoelectric power factor of the n-type composite film was proven to be air stable. A grazing-incidence wide-angle X-ray diffraction analysis indicated a significant impact of introducing the thieno[3,2-b]thiophene core into the backbone of the nickel complex on the orientation within the composite films.

Surface crystalline structure of thin poly(l-lactide) films determined by the long-range substrate effect

Due to the stepwise crystallization behavior of polymorphous poly(l-lactide) (PLLA) films, the surface crystalline structures of thin PLLA films supported on Si/SiOx substrates with various thicknesses of both the film and adsorbed layer were investigated separately by grazing incidence wide-angle X-ray diffraction (GIWAXD). An unusual highly packed α-form crystal was observed at the surface at a crystallization temperature of 346 K, which transformed to a loosely packed δ-form (or called α′-form) crystal with decreasing film thickness or increasing adsorbed layer thickness. The mobility of the surface chains of PLLA films was scaled by the surface crystallization rate to elucidate the substrate effect on the corresponding surface crystalline structure. It was found that if the surface mobility is suppressed by the long-range substrate effect from much faster to slower than that in the bulk, then the surface crystalline structure changes from α-crystal to δ-crystal. A phase diagram was ultimately constructed to predict the surface crystalline structure at 346 K in thin PLLA films with various thicknesses of both the film and adsorbed layer.

Morphological study of isotactic polypropylene thin films on different substrates using grazing incidence wide-angle X-ray diffraction

Isotactic polypropylene (iPP) is one of the most commonly used polymers owing to its excellent mechanical properties and well-balanced physical properties. These properties can be achieved and controlled through a better understanding of its hierarchical structures. The crystal structures of iPP thin films of ∼120 nm thickness formed on graphite and silicon substrates were investigated via grazing incidence wide-angle X-ray diffraction (GIWAXD) with hard and tender X-rays along with grazing incidence small-angle X-ray scattering, atomic force microscopy, and transmission electron microscopy. The lamellae were found to be edge-on-oriented on the graphite substrate due to epitaxial iPP crystal growth and flat-on-oriented on the silicon substrate due to iPP crystal growth along the thermodynamically dominant orientation. GIWAXD results obtained with tender X-rays revealed that the orientation of the crystal lamellae did not change along the thickness direction and that the degree of crystallinity at the surface was lower than that in the interior of the iPP thin films for each substrate. These results indicate that crystallization at the substrate-film interface played a significant role in the formation of the crystal structure of the iPP thin film, that is, the crystals grew throughout the thin films along the substrate-induced orientation even in the case of edge-on orientation, where the growth axes of the crosshatched lamellae were not parallel to the thickness direction. The relationship between the growth axes of lamella and the growth of surface-induced orientation along the normal direction of the substrates was successfully clarified for the first time using the thin film systems. The obtained results can be extended to interface-induced crystallization inside bulk composite materials.

Confined Crystallization in the Self-Assembled Nanostructures of Cellulose Nanocrystals and Polyethylene Glycol

Thin layers of semicrystallized polymers covered on nanoparticles significantly influence the multiple properties of their nanocomposites because of the confined crystallization of polymers. Cellulose nanocrystal (CNC) nanorods have a hydroxy-rich surface that favors the hydrogen-bonding interaction with polymers and a twisted nanostructure, which can construct a chiral nematic liquid-crystal phase scaffold for the filling of polymers. All these make CNCs’ self-assembled nanostructure a unique confined condition for polymers. Understanding the crystallization of polymers in the coassembled CNC/polymer composites presents a challenge in this regard. In this study, we focus on the confinement crystallization in the coassembled composites of CNCs and poly(ethylene glycol)(PEG). The composition-dependent changes in composite morphology and crystallization have been extensively characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, synchrotronic powder X-ray diffraction, synchrotronic grazing incidence wide-angle X-ray diffraction, and differential scanning calorimetry. At low PEG content (10 wt.%), strong confinement has been identified, showing an extremely low crystallinity with tiny PEG crystallites. As the PEG reached 30 wt.%, the PEG (120) plane with the flat-on orientation of the crystal lamella appeared. As the PEG content increased continuously (40 wt.% to 50 wt.%), the intensity of the (120) plane of the PEG crystal became larger, accompanied by an increasing flat-on orientation degree. When the PEG weight percentage was up to 60 wt.%, the crystals grew randomly, losing their preferential orientation. The free growth of PEG crystals also induced a significantly decreased orientation degree of CNCs. The CNC/PEG system presents a mutual influence from two components, which enriches our understanding of the coassembly and confined crystallization of polymer composites. It will benefit the further modulation of CNC-based nanocomposites, both in their structures and properties.

An effect of crystallographic distortion on carrier mobility in poly(3-hexylthiophene) thin films

The aggregation states and physical properties of polymers in thin films deviate from those found in the bulk. Although an effect of the thickness on the carrier mobility for thin films of poly(3-hexylthiophene) (P3HT) has been widely studied, there is a lack of discussion in terms of crystallographic distortion. Here, we demonstrate how the out-of-plane hole mobility in P3HT, which is a typical semiconducting polymer, changes with decreasing film thickness. Time-of-flight measurements with an analysis using the Gaussian disorder model revealed that the zero-field out-of-plane hole mobility decreased with decreasing thickness because of an increase in the energetical and spatial distribution of hopping sites. Grazing incidence wide-angle x-ray diffraction measurements revealed that such distributions of charge carriers were induced by the crystallographic distortion of P3HT in the thin films.

Analysis of the Performance of Narrow-Bandgap Organic Solar Cells Based on a Diketopyrrolopyrrole Polymer and a Nonfullerene Acceptor.

The combination of narrow-bandgap diketopyrrolopyrrole (DPP) polymers and nonfullerene acceptors (NFAs) seems well-matched for solar cells that exclusively absorb in the near infrared but they rarely provide high efficiency. One reason is that processing of the active layer is complicated by the fact that DPP-based polymers are generally only sufficiently soluble in chloroform (CF), while NFAs are preferably processed from halogenated aromatic solvents. By using a ternary solvent system consisting of CF, 1,8-diiodooctane (DIO), and chlorobenzene (CB), the short-circuit current density is increased by 50% in solar cells based on a DPP polymer (PDPP5T) and a NFA (IEICO-4F) compared to the use of CF with DIO only. However, the open-circuit voltage and fill factor are reduced. As a result, the efficiency improves from 3.4 to 4.8% only. The use of CB results in stronger aggregation of IEICO-4F as inferred from two-dimensional grazing-incidence wide-angle X-ray diffraction. Photo- and electroluminescence and mobility measurements indicate that the changes in performance can be ascribed to a more aggregated blend film in which charge generation is increased but nonradiative recombination is enhanced because of reduced hole mobility. Hence, while CB is essential to obtain well-ordered domains of IEICO-4F in blends with PDPP5T, the morphology and resulting hole mobility of PDPP5T domains remain suboptimal. The results identify the challenges in processing organic solar cells based on DPP polymers and NFAs as near-infrared absorbing photoactive layers.

Understanding the synergistic effect of mixed solvent annealing on perovskite film formation* *Project supported by the National Natural Science Foundation of China (Grant Nos. 21734009, 51473009, 21225209, 91427303, and 61805138). Portions of this research were carried out at beamline 7.3.3 at the Advanced Light Source, Molecular Foundry, Lawrence Berkeley National Laboratory, which was supported by the DOE, Office of Science,

Morphology control of perovskite films is of critical importance for high-performance photovoltaic devices. Although solvent vapor annealing (SVA) treatment has been widely used to improve the film quality efficiently, the detailed mechanism of film growth is still under construction, and there is still no consensus on the selection of solvents and volume for further optimization. Here, a series of solvents (DMF, DMSO, mixed DMF/DMSO) were opted for exploring their impact on fundamental structural and physical properties of perovskite films and the performance of corresponding devices. Mixed solvent SVA treatment resulted in unique benefits that integrated the advantages of each solvent, generating a champion device efficiency of 19.76% with improved humidity and thermal stability. The crystallization mechanism was constructed by conducting grazing-incidence wide-angle x-ray diffraction (GIWAXS) characterizations, showing that dissolution and recrystallization dominated the film formation. A proper choice of solvent and its volume balancing the two processes thus afforded the desired perovskite film. This study reveals the underlying process of film formation, paving the way to producing energy-harvesting materials in a controlled manner towards energy-efficient and stable perovskite-based devices.

Thermal Behavior of Anhydrous Ascorbic Acid 6‐Palmitate with Trace of Decomposition

AbstractAscorbic acid 6‐palmitate (AsP) is an industrially utilized antioxidant and amphiphilic lipid, which forms a liquid crystalline (LC) phase. Herein, we describe the basic thermal behavior of AsP under anhydrous condition. Grazing‐incidence wide‐angle X‐ray‐diffraction (GI‐WAXD) measurements using a two‐dimensional detector (2D‐GI‐WAXD) and perpendicularly aligned AsP films, together with thermal analysis, showed that the AsP forms only a lamellar LC phase above its melting point (Tm); however, when the LC phase was cooled to facilitate annealing and recrystallization, crystals (Cr) formed with a low degree of crystallinity. Furthermore, a composite system, consisting of the Cr phase and LC phase of AsP, was obtained upon reheating. These anomalous phenomena were likely caused by trace dimerization and decomposition of AsP at a temperature just above Tm, although thermal decomposition accompanied by weight reduction occurred at a much higher temperature in the isotropic phase (IL). Thus, the basic thermal behavior of AsP, which is essential for its use, was unveiled.

3,4-Ethylenedioxythiophene-Based Isomer-Free Quinoidal Building Block and Conjugated Polymers for Organic Field-Effect Transistors

Since quinoidal molecules have double-bond linkages between aromatic rings, they have many advantages for efficient charge transport resulting from high planarity and extended π-conjugation length. However, they unavoidably generate some isomers, which cause difficulty in purification and characterization. In this study, sulfur–oxygen conformation locking and steric repulsion approach is introduced to manipulate syn- and anti-isomerization of a quinoidal building block (bis-QEDOT). As a result, isomer-free bis-QEDOT is synthesized by introducing the 3,4-ethylenedioxy group, and the geometrical structure of bis-QEDOT is identified by thin-layer chromatography, 1H NMR, and density functional theory calculation. Furthermore, thiophene (T), bithiophene (2T), and thienylene vinylene (TV) as π-conjugated building blocks are polymerized with bis-QEDOT. Due to the quinoid structure, PQEDOT-T, PQEDOT-2T, and PQEDOT-TV show an intensified near-IR absorption and a low band gap around ∼1.16 eV. Grazing incidence wide-angle X-ray diffraction reveals that three quinoidal polymers show in the (h00) diffraction peaks up to third order after thermal annealing at 250 °C, demonstrating high crystallinity of the films. Finally, the electrical properties of the three polymers are investigated as an active layer in organic field-effect transistors showing hole mobilities of 4.3 × 10–2 (PQEDOT-T), 1.8 × 10–2 (PQEDOT-2T), and 7.8 × 10–3 cm2 V–1 s–1 (PQEDOT-TV).

Molecular aggregation structure and water repellency of Poly(perfluorohexyl acrylate) with a carbamate linkage

Liquid repellency of comb-shaped polyacrylates with perfluoroalkyl side-chains associates with the ordered structure of the side-chains at the surface. The molecular aggregation structure and surface properties of poly{2-[(perfluorohexylethyl)carbamate]ethyl}acrylate (PFAUr-C6) were studied using differential scanning calorimetry (DSC), polarized optical microscopy (POM), powder wide-angle X-ray diffraction (WAXD), grazing incidence wide-angle X-ray diffraction (GI-WAXD), temperature-controlled Fourier transform infrared spectroscopy (FTIR), contact angle measurements, and X-ray photoelectron spectroscopy (XPS). Poly[2-(perfluorohexyl)ethyl]acrylate (PFA-C6) was compared with PFAUr-C6 to verify the effect of carbamate linkage on the aggregation structure and surface properties. The perfluorohexyl groups in PFAUr-C6 produced a double-layered smectic structure, whereas the perfluorohexyl groups in PFA-C6 showed no ordered structure. The double-layered smectic structure in PFAUr-C6 was induced by the hydrogen bonding interaction in the carbamate linkers. PFAUr-C6 showed poor water repellency similar to PFA-C6 because of the rapid surface rearrangement. Although the perfluorohexyl groups produced smectic order structure at the film surface, the lack of positional order in the smectic layers and the low ordered structure content allowed the surface rearrangement.

Tweaking the Molecular Geometry of a Tetraperylenediimide Acceptor.

Partial flattening of the spatially extended molecular scaffold has been employed as an effective tactic to improve the device performance of a perylenediimide (PDI)-based small-molecule acceptor because the less twisted yet not completely planar molecular geometry is anticipated to improve the molecular packing and thereby attain a more suitable balance between the carrier transport ability and phase domain size. A small-molecule acceptor BF-PDI comprising four α-substituted PDI units attached around a 9,9'-bifluorenylidene (BF) central moiety is designed and studied in polymer solar cells. The BF group is deemed a ring-fused analogue of the tetraphenylethylene (TPE) unit. Due to the less twisted and better conjugated BF skeleton, BF-PDI displays more delocalized lowest unoccupied molecular orbital. By virtue of both the electronic and steric effects, BF-PDI is suggested to bring about superior intermolecular stacking and donor-acceptor phase separation morphology in blend films. Indeed, the experimental results show that BF-PDI displays improved charge transport ability and a higher power-conversion efficiency of 8.05% than that of TPE-PDI. Grazing-incidence wide-angle X-ray diffraction and resonant soft X-ray scattering confirm the more compact and ordered molecular packing as well as smaller domain sizes in the P3TEA/BF-PDI blend.

Molecular orientation and stability of poly(3-hexylthiophene) nanogratings affected by the fabricated solvent vapor.

During the nanoimprinting lithography (NIL) process, the role of solvent vapor in fabricating the pattern structure and inducing the molecular alignment of nanoimprinted polymer film has been attracting significant attention. We demonstrate here that the molecular orientation and thermal stability of poly(3-hexylthiophene) (P3HT) nanograting film can be affected obviously by the fabricated solvent vapor. A solvent-vapor nanoimprinting lithography (SV-NIL) technique based on a polydimethylsiloxane (PDMS) template is employed to fabricate a P3HT nanograting structure film successfully and solvent vapor is offered by chlorobenzene, chloroform and carbon disulphide, respectively. The molecular orientation of the polymer film is carefully characterized by grazing incidence wide angle X-ray diffraction (GIWAXD) measurements to investigate the effect of various solvent vapors on the molecular orientation of the P3HT nanograting film. For the P3HT nanograting film fabricated by chloroform and chlorobenzene solvent, the edge-on molecular orientation of the typical form II crystallographic structure is induced. However, this indicates that there are both the face-on molecular orientations of the form II and form I crystallographic conformation present for the P3HT nanograting film fabricated by carbon disulphide solvent. Therefore, the fabricated solvent vapor plays a significant role in determining the formation of the molecular orientation of the polymer nanostructure. Then, the role of thermal annealing in the stability of the molecular orientation was investigated for the P3HT nanograting film after a fixed temperature. As for the annealed nanograting film fabricated by chlorobenzene and chloroform solvent vapor, a single edge-on molecular orientation mode of the form I crystallographic structure has been obtained. However, for the annealed nanograting film fabricated by the carbon disulphide solvent, the edge-on and face-on molecular orientations of the form I crystallographic structure are still retained. This indicates that the stability of the form II crystallographic conformation is mainly dependent on the thermal annealing process. Therefore, after the annealing process, the final determining of the molecular alignment and crystallographic conformation depends significantly on the orientation type of the nanograting film before the annealing history, and it can be further inferred that the molecular orientation of the annealed polymer film is still affected by the fabricated solvent vapor significantly. Thus this will provide new understanding and guidance for the research of the topographical structure and molecular alignment of conjugated polymers.

A Nanoconfinement Effect Imposed by the Limited End-to-End Distance of the Grafted Chains on a Molecular Aggregation of Polymer Brushes with Crystalline Side Groups

We demonstrated, using grazing incidence wide-angle X-ray diffraction (GI-WAXD), sum frequency generational spectroscopy (SFG), and atomic force microscopy (AFM), that the aggregation state and mol...

Aggregation States of Poly(4-methylpentene-1) at a Solid Interface

A thin film of poly(4-methylpentene-1) (P4MP1) was prepared on a quartz substrate, which was a model system of an interface in filler-reinforced semicrystalline polymer composites. Grazing-incidence wide-angle X-ray diffraction measurements revealed that P4MP1 in the thin film after isothermal crystallization formed a Form I crystal polymorph composed of a tetragonal unit cell with a 72 helix, in which the chain axis was oriented along the direction parallel to the quartz interface. Combining sum-frequency generation vibrational spectroscopy with molecular dynamics simulation enabled us to gain access to the local conformation of P4MP1 chains at the quartz interface and the changes that occurred with isothermal crystallization. Finally, the way in which the initial chain orientation at the substrate interface impacted the crystalline structure in the thin film was discussed. A poly(4-methylpentene-1) (P4MP1) film was prepared on a quartz substrate, which was a model system of interfaces in a filler-reinforced semicrystalline polymer composite. Grazing-incidence wide-angle X-ray diffraction measurements revealed that P4MP1 in the film after the isothermal crystallization formed a Form I crystal polymorph, in which the chain axis was oriented along the direction parallel to the quartz interface. Combining sum-frequency generation vibrational spectroscopy with molecular dynamics simulation enabled us to study the local conformation of P4MP1 chains at the quartz interface and the changes that occurred with isothermal crystallization.

Smectic ordered structure and water repellency of a poly(fluoroalkyl acrylate) with a carbamate linker

Thermal behavior, molecular aggregation structure, and water repellency for poly{2-[(perfluorooctylethyl)carbamate]ethyl}acrylate (PFAUr-C8) were studied by differential scanning calorimetry (DSC), polarized optical microscopy (POM), wide-angle X-ray diffraction (WAXD), grazing-incidence wide-angle X-ray diffraction (GI-WAXD), contact angle measurements, and X-ray photoelectron spectroscopy (XPS). The impact of the carbamate linker was verified by comparison with poly[2-(perfluorooctyl)ethyl]acrylate (PFA-C8). PFAUr-C8 exhibited two phase transitions at 357 K and 416 K, whereas PFA-C8 showed a single-phase transition at 347 K. Both PFAUr-C8 and PFA-C8 formed a bilayered hexatic smectic-B phase at room temperature. Although the lamellar structure for the fluoroalkyl (Rf) groups was immediately lost in PFA-C8 after disordering of the lateral translational order, PFAUr-C8 maintained a stacked lamellar structure without lateral translational order. PFAUr-C8 exhibited excellent water repellency at room temperature similar to PFA-C8. The outstanding thermal stability of the lamellar structure in PFAUr-C8 is attributed to the cohesive interaction of the carbamate linkage.

Organic-Inorganic Hybrid Thin Films Fabricated by Layer-by-Layer Assembly of the Phosphorylated Cellulose Nanocrystal and Imogolite Nanotubes.

Phosphorylated cellulose nanocrystal (P-CNC)/imogolite nanotube (natural aluminosilicate nanotube) hybrid thin films were fabricated by spin-assisted layer-by-layer assembly. Phosphorylation of CNC with diammonium hydrogen phosphate ((NH4)2HPO4) was carried out to introduce phosphate groups on the CNC surface for enhanced interaction with imogolite. Structure of the P-CNC/imogolite thin film was characterized by atomic force microscopy, scanning electron microscopy, X-ray diffraction (XRD), and grazing incidence wide-angle XRD. The film thickness increased linearly with the increment of the P-CNC/imogolite bilayer. Benefitting from the strong affinity between the phosphate group of the P-CNC and the Al-OH group of imogolite, the P-CNC/imogolite thin films were quite stable in water within a wide range of pH values, compared with the deterioration of the CNC/imogolite film under same soaking conditions.