scholarly journals Thermocapillary Marangoni Flows in Azopolymers

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2464
Author(s):  
Andrzej Miniewicz ◽  
Anna Sobolewska ◽  
Wojciech Piotrowski ◽  
Pawel Karpinski ◽  
Stanislaw Bartkiewicz ◽  
...  
Keyword(s):  
Liquid Crystalline ◽  
Mass Movement ◽  
Polymer Surface ◽  
Polarized Light ◽  
Marangoni Effect ◽  
Mass Motion ◽  
Polymeric Liquid ◽  
Force Microscopy ◽  
Atomic Force ◽  
Linearly Polarized

It is well known that light-induced multiple trans-cis-trans photoisomerizations of azobenzene derivatives attached to various matrices (polymeric, liquid crystalline polymers) result in polymer mass movement leading to generation of surface reliefs. The reliefs can be produced at small as well as at large light intensities. When linearly polarized light is used in the process, directional photo-induced molecular orientation of the azo molecules occurs, which leads to the generation of optical anisotropy in the system, providing that thermal effects are negligible. On the other hand, large reliefs are observed at relatively strong laser intensities when the optofluidization process is particularly effective. In this article, we describe the competitive thermocapillary Marangoni effect of polymer mass motion. We experimentally prove that the Marangoni effect occurs simultaneously with the optofluidization process. It destroys the orientation of the azopolymer molecules and results in cancelation of the photo-induced birefringence. Our experimental observations of polymer surface topography with atomic force microscopy are supported by suitable modelings.

Wrinkling Poly(trimethylene 2,5-Furanoate) Free-standing Films: Nanostructure Formation and Physical Properties

2020 ◽  
Author(s):  
Michelina Soccio ◽  
Nadia Lotti ◽  
Andrea Munari ◽  
Esther Rebollar ◽  
Daniel E Martínez-Tong
Keyword(s):  
Irradiation Time ◽  
Polymer Surface ◽  
Laser Source ◽  
Free Standing ◽  
Force Microscopy ◽  
Nanostructure Formation ◽  
Physicochemical Changes ◽  
Angle Measurements ◽  
Atomic Force ◽  
Contact Angle Measurements

<p>Nanostructured wrinkles were developed on fully bio-based poly(trimethylene furanoate) (PTF) films by using the technique of Laser Induced Periodic Surface Structures (LIPSS). We investigated the effect of irradiation time on wrinkle formation using an UV pulsed laser source, at a fluence of 8 mJ/cm2. It was found that the pulse range between 600 and 4800 pulses allowed formation of periodic nanometric ripples. The nanostructured surface was studied using a combined macro- and nanoscale approach. We evaluated possible physicochemical changes taking place on the polymer surface after irradiation by infrared spectroscopy, contact angle measurements and atomic force microscopy. The macroscopic physicochemical properties of PTF showed almost no changes after nanostructure formation, differently from the results previously found for the terephthalic counterparts, as poly(ethyleneterephthalate), PET, and poly(trimethyleneterephthalate), PTT. The surface mechanical properties of the nanostructured PTF were found to be improved, as evidenced by nanomechanical force spectroscopy measurements. In particular, an increased Young’s modulus and higher stiffness for the nanostructured sample were measured. <br></p>

scholarly journals Steady state charge conduction through solution processed liquid crystalline lanthanide bisphthalocyanine films

2019 ◽  
Vol 23 (11n12) ◽  
pp. 1603-1615
Author(s):  
Chandana Pal ◽  
Isabelle Chambrier ◽  
Andrew N. Cammidge ◽  
A. K. Sharma ◽  
Asim K. Ray
Keyword(s):  
Metal Ions ◽  
Liquid Crystalline ◽  
Microscopy Study ◽  
Individual Characteristics ◽  
Central Metal ◽  
Force Microscopy ◽  
Atomic Force ◽  
Double Decker ◽  
Order Of Magnitude ◽  
Chain Lengths

In-plane electrical characteristics of non-peripherally octyl(C[Formula: see text]H[Formula: see text]- and hexyl(C[Formula: see text]H[Formula: see text]-substituted liquid crystalline (LC) double decker lanthanide bisphthalocyanine (LnPc[Formula: see text] complexes with central metal ions lutetium (Lu), and gadolinium (Gd) have been measured in thin film formulations on interdigitated gold (Au) electrodes for the applied voltage ([Formula: see text] range of [Formula: see text]. The conduction mechanism is found to be Ohmic within the bias of [Formula: see text] while the bulk limited Poole–Frenkel mechanism is responsible for the higher bias. The compounds show individual characteristics depending on the central metal ions, substituent chain lengths and their mesophases. Values of 67.55 [Formula: see text]cm[Formula: see text] and 42.31 [Formula: see text]cm[Formula: see text] have been obtained for room temperature in-plane Ohmic conductivity of as-deposited octyl lutetium (C[Formula: see text]LuPc[Formula: see text] and hexyl gadolinium (C[Formula: see text]GdPc[Formula: see text] films, respectively while C[Formula: see text]GdPc[Formula: see text] films exhibit nearly two orders of magnitude smaller conductivity. On annealing at 80[Formula: see text]C, Ohmic conductivities of C[Formula: see text]LuPc[Formula: see text] and C[Formula: see text]GdPc[Formula: see text] are found to have increased but the conductivity of C[Formula: see text]GdPc[Formula: see text] decreased by more than one order of magnitude to 1.5 [Formula: see text]cm[Formula: see text]. For physical interpretation of the charge transport behavior of these three molecules, their UV-vis optical absorption spectra in the solution and in as-deposited and annealed solid phases and atomic force microscopy study have been performed. It is believed that both orientation and positional reorganizations are responsible, depending upon the size of the central ion and side chain length.

scholarly journals Influence of Oxidation Degree of Graphene Oxide on the Shear Rheology of Poly(ethylene glycol) Suspensions

Fluids ◽  
2020 ◽  
Vol 5 (2) ◽  
pp. 41 ◽  
Author(s):  
Yago Soares ◽  
Elyff Cargnin ◽  
Mônica Naccache ◽  
Ricardo Andrade
Keyword(s):  
Graphene Oxide ◽  
Rheological Behavior ◽  
Structural Characteristics ◽  
Rheological Characterization ◽  
Polymeric Liquid ◽  
Oxidation Degree ◽  
Force Microscopy ◽  
Fluid Behavior ◽  
Atomic Force ◽  
Poly Ethylene

This work studies the influence of the concentration and oxidation degree on the rheological behavior of graphene oxide (GO) nanosheets dispersed on polyethylene glycol (PEG). The rheological characterization was fulfilled in shear flow through rotational rheometry measurements, in steady, transient and oscillatory regimes. Graphene oxide was prepared by chemical exfoliation of graphite using the modified Hummers method. The morphological and structural characteristics originating from the synthesis were analyzed by X-ray diffraction, Raman spectroscopy, thermogravimetric analysis, Fourier transform infrared spectroscopy, and atomic force microscopy. It is shown that higher oxidation times increase the functional groups, which leads to a higher dispersion and exfoliation of GO sheets in the PEG. Moreover, the addition of GO in a PEG solution results in significant growth of the suspension viscosity, and a change of the fluid behavior from Newtonian to pseudoplastic. This effect is related to the concentration and oxidation level of the obtained GO particles. The results obtained aim to contribute towards the understanding of the interactions between the GO and the polymeric liquid matrix, and their influence on the suspension rheological behavior.

Review of Polymer Surface Modification Method

2016 ◽  
Vol 852 ◽  
pp. 626-631 ◽  
Author(s):  
Li Yuan Yu ◽  
Bo Zhu ◽  
Xun Cai ◽  
Yong Wei Wang ◽  
Rong Huan Han ◽  
...  
Keyword(s):  
Surface Modification ◽  
Polymer Surface ◽  
Processing Method ◽  
Surface Grafting ◽  
Atomic Force Microscopy Probe ◽  
Force Microscopy ◽  
Atomic Force ◽  
Irradiation Treatment ◽  
Modification Method ◽  
Polymer Surface Modification

This paper reviewed a variety of methods of polymer surface modification, which mainly includes Solution processing method, Plasma treatment，Surface grafting method，Irradiation treatment and method of Atomic force microscopy probe shock , and the specific polymer material combined with the modification method and its modification mechanism was introduced in detail.Polymer has very extensive application both in chemical fields and in daily life, but due to its poor surface hydrophilicity and wear resistance, the further application of polymer materials were limited. In order to improve its surface properties, modification are needed on the surface of the polymer. Polymer surface modification means to operate on the surface of polymer within the scope of nanometer level, and give some new properties on material surface, such as hydrophilicity, scratch resistance, under the premise of without affecting the material ontic properties.There are many methods of polymer surface modification. This paper reviewed Solution processing method, Plasma treatment，Surface grafting method，Irradiation treatment and method of Atomic force microscopy probe shock . Different methods of modification combined with specific materials are introduced as follow.

scholarly journals Hybrid Nanosystems Based on Metal-Containing Mesogenic CyanoAlkyl and Alkoxybiphenyls

Crystals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 77
Author(s):  
Tatyana I. Shabatina ◽  
Yurii N. Morosov
Keyword(s):  
Liquid Crystalline ◽  
Metal Species ◽  
Force Microscopy ◽  
Atomic Force ◽  
Liquid Crystalline Phases ◽  
Metal Contents ◽  
Visible Spectra ◽  
Hybrid Nanosystems ◽  
Nematic Phases ◽  
Small Clusters

The paper reviews the results of the authors on the production of hybrid nanosystems based on liquid crystalline (LC) long-chain cyano(alkyl and alkoxy)biphenyls (5CB, 5OCB, and 8CCB) including nanosized metal species. The samples were obtained through the direct incorporation of metal (silver and copper) atoms and small clusters into mesogenic CB matrices via a low temperature co-condensation technique, and the formation of biligand metal complexes were revealed by FTIR and ESR-spectroscopy. The heating of the systems led to the controlled growth of metal clusters and nanosized metal particles of the definite size beginning from 1 up to 200 nanometers, and their highly-ordered assemblies stabilized in the solid and liquid crystalline phases. It is shown that supramolecular ordering in different LC phases of cyanobiphenyl matrices determines the size and shape of nanosized metal species that are formed in the systems under investigation, as well as the morphology of their aggregates. TEM and atomic force microscopy (AFM) data revealed the existence of orientationally-ordered nanostructures in the nematic phases of 5CB and 5OCB. The growth of quasi-fractal 2D-aggregates was shown for layer-structured smectic mesophase of 8CB. The UV–Visible spectra of hybrid metal–mesogenic nanosystems Ag-5CB and Cu-5CB that were incorporated into polymeric films revealed intensive plasmonic bands at 400–450 nm, similar to silver nanoparticles, and 540–650 nm, similar to copper nanoparticles. The increasing of the metal contents in the samples caused the growth of highly anisometric shaped metal rods, with the ratio of the length to the diameter being more than 10 and plasmonic bands at region of λ ≥ 650 nm.

scholarly journals Hierarchical Characterization and Nanomechanical Assessment of Biomimetic Scaffolds Mimicking Lamellar Bone via Atomic Force Microscopy Cantilever-Based Nanoindentation

Materials ◽  
2018 ◽  
Vol 11 (7) ◽  
pp. 1257 ◽  
Author(s):  
Brian Wingender ◽  
Yongliang Ni ◽  
Yifan Zhang ◽  
Curtis Taylor ◽  
Laurie Gower
Keyword(s):  
Mechanical Properties ◽  
Atomic Force Microscopy ◽  
Hierarchical Structure ◽  
Liquid Crystalline ◽  
Structural Motif ◽  
Positive Trend ◽  
Bovine Bone ◽  
Lamellar Bone ◽  
Force Microscopy ◽  
Atomic Force

The hierarchical structure of bone and intrinsic material properties of its two primary constituents, carbonated apatite and fibrillar collagen, when being synergistically organized into an interpenetrating hard-soft composite, contribute to its excellent mechanical properties. Lamellar bone is the predominant structural motif in mammalian hard tissues; therefore, we believe the fabrication of a collagen/apatite composite with a hierarchical structure that emulates bone, consisting of a dense lamellar microstructure and a mineralized collagen fibril nanostructure, is an important first step toward the goal of regenerative bone tissue engineering. In this work, we exploit the liquid crystalline properties of collagen to fabricate dense matrices that assemble with cholesteric organization. The matrices were crosslinked via carbodiimide chemistry to improve mechanical properties, and are subsequently mineralized via the polymer-induced liquid-precursor (PILP) process to promote intrafibrillar mineralization. Neither the crosslinking procedure nor the mineralization affected the cholesteric collagen microstructures; notably, there was a positive trend toward higher stiffness with increasing crosslink density when measured by cantilever-based atomic force microscopy (AFM) nanoindentation. In the dry state, the average moduli of moderately (X51; 4.8 ± 4.3 GPa) and highly (X76; 7.8 ± 6.7 GPa) crosslinked PILP-mineralized liquid crystalline collagen (LCC) scaffolds were higher than the average modulus of bovine bone (5.5 ± 5.6 GPa).

Annealing effects on the electrical conductivity of polymerized liquid crystalline 3,4-ethylenedioxythiophene derivatives

e-Polymers ◽  
2006 ◽  
Vol 6 (1) ◽  
Author(s):  
Noelle Wrubbel ◽  
Helmut Ritter ◽  
Knud Reuter ◽  
Alexander Karbach ◽  
Doris Drechsler
Keyword(s):  
Electrical Conductivity ◽  
Atomic Force Microscopy ◽  
Liquid Crystal ◽  
Liquid Crystalline ◽  
Electrically Conductive ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Annealing Effects

Abstract3,4-Ethylenedioxythiophene derivatives with aromatic, in most cases mesogenic, side groups were synthesized and their liquid crystal behaviour was characterized. These monomers were polymerized oxidatively to charged, electrically conductive polythiophenes. X-ray and atomic force microscopy studies were performed. Films of theses polythiophenes achieved via in situ polymerization were prone to a significant increase of the conductivity by annealing.

Measurement of the loss tangent of a thin polymeric film using the atomic force microscope

2004 ◽  
Vol 19 (1) ◽  
pp. 387-395 ◽  
Author(s):  
P.M. McGuiggan ◽  
D.J. Yarusso
Keyword(s):  
Atomic Force Microscope ◽  
Loss Tangent ◽  
Oscillation Amplitude ◽  
Polymer Surface ◽  
Pressure Sensitive Adhesive ◽  
Force Microscopy ◽  
Atomic Force ◽  
Microscopy Measurement ◽  
Microscope Technique ◽  
Tan Δ

An atomic force microscope was used to measure the loss tangent, tan δ, of a pressure-sensitive adhesive transfer tape as a function of frequency (0.01 to 10 Hz). For the measurement, the sample was oscillated normal to the surface and the response of the cantilever resting on the polymer surface (as measured via the photodiode) was monitored. Both oscillation amplitude and phase were recorded as a function of frequency. The atomic force microscopy measurement gave the same frequency dependence of tan δ as that measured by a dynamic shear rheometer on a film 20 times thicker. The results demonstrate that the atomic force microscope technique can quantitatively measure rheological properties of soft thin polymeric films.

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