A. Tracz

Remote hydrogen–nitrogen plasma chemical vapor deposition from a tetramethyldisilazane source. Part 1. Mechanism of the process, structure and surface morphology of deposited amorphous hydrogenated silicon carbonitride filmsElectronic supplementary information (ESI) available: deconvoluted emission and IR spectra of a-Si–N–C–H films. See http://www.rsc.org/suppdata/jm/b2/b211415c/

Amorphous hydrogenated silicon carbonitride films were produced by remote plasma chemical vapor deposition (RP-CVD) from 1,1,3,3-tetramethyldisilazane (TMDSN) as the single-source compound using a H2–N2 upstream-gas-mixture for plasma generation. The reactivity of particular TMDSN bonds in the RP-CVD initiation step has been examined using a hexamethyldisilazane model compound in the deposition experiments. The active species contributing to RP-CVD were identified by optical emission spectroscopic analysis of the plasma region. The films were examined using Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and atomic force microscopy. The effect of N2 content in the H2–N2 upstream-gas-mixture on plasma generation of the active species, growth rate, chemical structure, and surface morphology of the resulting films is reported.

Synthesis of a paraffin phase change material microencapsulated in a siloxane polymer

The coemulsification method suitable for the formulation of microcapsules of n-eicosane coated with a polysiloxane is developed. This method allows to synthesize core–shell microcapsules of paraffin which have the shape of spheres or distorted spheres and are designed for the use as phase change materials. The microcapsules are formed in aqueous phase by the precipitation of n-eicosane together with modified polyhydromethylsiloxane from a common solvent which is miscible with aqueous media. The polysiloxane is modified by the attachment of silylvinyl and alkoxy functions before coemulsification with the paraffin. It also contains the Pt(0) Karstedt catalyst. The microcapsules formed by coemulsification are stabilized by the in situ cross-linking of the polysiloxane shell. The shell is additionally modified by the in situ generation of silanol groups which provide colloidal stabilization of microspheres in aqueous phase. Microcapsules were studied by DSC, SEM, optical polarized microscope, and by thermooptical analysis (TOA).

New transparent, colorless, metallically conductive polymer films and their electrochemical transformations

New surface conductive polymer composite films exhibiting extraordinary properties: high conductivity with metallic temperature dependence and exceptionally high transparency are presented. The conducting networks in these materials are formed of plate-like nanocrystals of bis(ethylenedioxy)tetrathiafulvalene (BEDO-TTF) salts with iodine or bromine. The films with bromine salts are colorless and transparent while those with iodine are colored. It is demonstrated that colored films with (BEDO-TTF)/iodine networks can be electrochemically transformed into highly transparent, practically colorless materials without deterioration of the conducting network. The resulting metallically conducting polymer materials show the highest transparency among conductive composites reported so far.

Highly—Oriented BEDO-TTF Molecules in Metallic Polymer Composites

Abstract Transport and optical properties of the metallic reticulate-doped polymer composites based on bis(ethylenedioxy)tetrathiafulvalene (BEDO-TTF) complexes are investigated, and compared with the structural and physical properties of the respective bulk crystals. Exposing the surface of polycarbonate (PC) film containing the molecularly dispersed donor to the solvent/(iodine or bromine) vapor converted the donor into charge-transfer (CT) complexes, which dominate the conducting and thermoelectric properties of the composites. Both film surfaces doped with bromine and iodine are well conducting, showing metallic behavior down to low temperatures. A characteristic CT band for the highly conducting states of the partially oxidized BEDO-TTF molecules appeared in the infrared region. However, compared with the respective bulk crystal, absorptions of the intramolecular excitation of the donor molecules are greatly diminished for the incident light perpendicular to the film surface. The PC film of (BEDO-TTF...

Superhydrophobic properties of cotton woven fabrics with conducting 3D networks of multiwall carbon nanotubes, MWCNTs

This article presents the findings concerning the preparation and properties of cotton woven fabrics with a conductive network made of multiwall carbon nanotubes deposited on the fiber surface by the padding method. The next stage of treatment consisted of imparting superhydrophobic properties to the fabrics in solution with methyltrichlorosilane (MTCS) in a waterless medium. The tests performed show that the state of surface and water content in cotton fibers exerts a significant influence on the hydrophobic properties of the analyzed samples. In order to explain the differences in hydrophobic properties, the morphology of the cotton fabric surface was examined using samples with various water contents. The formation mechanism of MTCS coatings on cotton fabric has been proposed.

Metallic polymer composites with bis(ethylenedioxy)-tetrathiafulvalene salts. Preparation–properties relationship

Abstract The relationship between preparation conditions and properties of surface-conductive composites obtained by crystallization of low molecular weight organic conductors in polymer matrices (reticulate doped polymers) is investigated. By optimization of the preparation procedure we have obtained the first organic conductive composites which show metallic surface conductivity without any additional treatment. Surface-conductive polycarbonate (PC) films with bis(ethylenedioxy)-tetrathiafulvalene (BEDO-TTF) salts with iodine and bromine as the additives were obtained by the two-step reticulate doping method. BEDO-TTF content in PC was 1 wt.%. Due to the strong tendency of BEDO-TTF to form organic metals the films obtained under optimum conditions show exceptionally high surface conductivity (even above 10−3 S/□ for both I and Br salts), and exhibit metal-like temperature dependence of conductivity in a broad temperature range (even down to at least 10 K). Depending on the preparation conditions (vapour composition, treatment time) it is also possible to obtain highly conductive films showing semiconductor-like temperature dependence or metal–insulator transition. Structure and morphology of the conductive network is characterized using scanning electron microscopy and X-ray diffraction. These results and optical absorption studies permit identification of the salts which are main components of the networks in most of the systems. When the conductive network is made of BEDO-TTF/Br salts the films show also exceptionally high transparency.

Stoichiometry of the CT complex crystallites in polymer films

The stoichiometry of the charge transfer (CT) complex which crystallised in a polymer solution during film casting has been studied by a spectrophotometric method. It was found that the donor-to-acceptor molar ratio changes from 1:2 to 1:1 and even more, depending on the film casting conditions. The composition of the CT complex crystals is also related to the morphology of the crystallites formed which strongly influence the properties of the doped films.

Submicroscopic structure of the TTT-TCNQ conductive network in reticulate-doped polymers revealed by SEM

Abstract The results obtained using high-voltage scanning electron microscopy (SEM), which enables observation of the structure of the conductive network within the surface layer of reticulate-doped polymer films, are reported. The submicroscopic structure of the tetrathiotetracene-tetracyanoquinodimethane (TTT-TCNQ) network in amorphous polymers is presented and its implications for the conductivity mechanism are discussed. The SEM pictures obtained reveal the fibrous internal structure of the conductive network in bulk-conductive films obtained using the amorphous polymers polycarbonate and poly(methylmethacrylate). TTT-TCNQ crystallites in the surface-conductive film have a different form in spite of the same polymer being used as the matrix.

Quaternized and sulfated xylan derivative films

Xylan quaternized sulfate films were prepared from beech xylan (X) and compared with fully sulfated xylan films (XS). When quaternized xylan (QX) was prepared in the first step (DS(Q)=0.55), than by sulfation of QX in the second step the fully substituted ampholytic derivative (QXS; DS(Q)=0.33; DS(S)=1.67) could be obtained. By sulfation in first step, xylan sulphate (SX, DS(S)=0.70) was obtained and by subsequent quaternization, SXQ film with DSQ=0.55 and DSS=0.33 which contained partially unsubstituted hydroxyls. The molar masses (M(n)) of the films soluble parts were increasing in order X<SX<SXQ<QX<XS<QXS. In all films there were some insoluble particles present as determined by the amount of recovered masses by SEC-MALS. The materials were further characterized by AFM, XRD, TG/DTG/DTA, NMR and mechanical testing. QXS and SXQ could form mechanically more stable films than XS specimens.

Continuous and discontinuous water release/intake of (BEDO-TTF)2Br(H2O)3 micro-crystals embedded in polymer film

Corresponding to the humidity, a transparent and metallically conductive polycarbonate thin film, at the surface of which micro-crystals of (bis(ethylenedioxy)tetrathiafulvalene)2Br(H2O)3 were embedded, showed quasi-reversible modulation of inter-conducting-layer distance in the micro-crystals and the surface resistance of the film. The best surface conductivity was observed at the relative humidity of ca. 10%. At the relative humidity of 5.4–8.6%, the coexistence of two kinds of structures of the micro-crystals having different interlayer distances was detected. Both of them showed humidity dependent electrical and structural modulations.