Pore shape control in nanoporous particle track etched membrane

This paper shows the possibility of preparing nanoporous particle track etched membranes (nanoPTM) with perfectly smooth and cylindrical pores from polycarbonate film. Interest in the template use of these nanoPTM for the production of polymeric or metallic nanoscale materials is also emphasized. (C) 2001 Elsevier Science B.V. All rights reserved

Track-etched Membrane - Dynamics of Pore Formation

The dynamics of pore formation during etching of heavy ion (Ar9+ -4.5 MeV/amu) irradiated bisphenol-A polycarbonate (PC) and polyethylene terephthalate (PET) films is determined by a conductivity cell. This work presents the theoretical basis of this method and describes the experimental procedure. The obtained results allow the determination of the track (V(t)) and bulk (V(g)) etch rates, and an estimate of the damage zone diameter in PC before etching

Modification of Peek Model Compounds and Peek Film By Energetic Heavy-ion and Ultraviolet Irradiations

To prepare nuclear track membranes from poly(aryl ether ether ketone) (PEEK) film, we first determined the modifications induced by heavy ion and UV irradiations in this polymer and two of its model compounds, paraphenoxy benzophenone (PPB) and diphenoxy benzophenone (DPB). This article displays the first results obtained by SEC, HPLC, DSC, FTIR, UV and C-13 NMR

Modifications induced by swift heavy ions in poly(hydroxybutyrate-hydroxyvalerate) (PHB/HV) and poly(epsilon-caprolactone) (PCL) films. Part 1. Thermal behaviour and molecular mass modifications

Modifications induced by different energetic heavy ions in poly(epsilon -caprolactone) (PCL) and poly(hydroxybutyrate-hydroxyvalerate) (PHB/HV) have been investigated by the differential scanning calorimetry (DSC) and steric exclusion chromatography (SEC). A certain dose of damages, depending mainly on the charge and mass of the ion and on the intensity of irradiation, has to be overcome in order to detect any effect on PHB/HV. Actually, at a given intensity of irradiation, superior to 10(10) ions/cm(2), the level of damage intensity increased with the increase in charge and mass of the ion. Moreover, according to the SEC results, there seems to be a critical mass and/or charge threshold above which the dominant type of damages changes. As a matter of fact, high-density irradiation with Ar9+ and Kr15+ resulted mainly in chain scission whereas cross-linking was dominant when irradiating the polymer with Xe24+ and Pb56+. Th, irradiation of PCL in the conditions studied did not modify significantly the values of the melting point, the crystallisation temperature and the molecular masses of the system studied. The main effect of the irradiation detected by the DSC is the cross-linking of the polymer chains. (C) 2000 Elsevier Science B.V. All rights reserved

Track-etch templates designed for micro- and nanofabrication

This paper reports on the advances made in the laboratory in the development of porous media by track-etching process, and on their use by research partners as templates for the micro- or nanofabrication of polymeric and metallic wires or tubules with interesting properties. It mainly relates to the development of nanoporous polycarbonate-based templates, and more precisely to pore-shape control in polycarbonate films, to the development of supported track-etch templates and to the feasibility of template patterning; recent results on the development of templates from polyimide support are also reported. Finally, some nanontaterial synthesis processes and properties are listed, with references to published papers. (C) 2003 Elsevier B.V. All rights reserved

Heavy-ion Tracks in Polycarbonate - Comparison With a Heavy-ion Irradiated Model-compound (diphenyl Carbonate)

The chemical modifications induced by energetic heavy ion irradiation of polycarbonate (PC) film are determined by GPC, HPLC, ESR, TGA, IR and UV spectrophotometry. The main results of the irradiation are creation of radicals, chain scission, cross-linking and appearance of new chemical groups in the main polymer chain. As far as the creation of new groups is concerned, they are determined by means of a model compound of PC: the diphenyl carbonate (DPC). The following compounds are identified after energetic heavy ion irradiation of DPC: salicylic acid, phenol, 4,4'-biphenol, 2,4'-biphenol, 2,2'-biphenol, 4-phenoxyphenol, 2-phenoxyphenol, phenyl ether, phenyl benzoate, phenyl salicylate, 2-phenylphenol and 2-phenoxyphenyl benzoate. A similarity between the heavy ion irradiation and a heat treatment has also been established with DPC. On the basis of these results, we try to give an explanation of the preferential attack along the tracks of the irradiated film. Also, an explanation of the well-known beneficial effect of an UV exposition of the irradiated film on the selectivity of this preferential chemical attack is suggested

Crystallization of bisphenol-A polycarbonate. III. Spherulitic growth rate of the plasticized polymer

For pt.II see ibid., vol.14, p.1367 (1976). Measurements of the spherulitic growth rates of bisphenol-/b A/ polycarbonate plasticized with pentaerythritol tetranonanoate (PETN), trimetallic acid tri(/b n/-octyl-/b n/-decyl)ester (TMDO), and tritolyl phosphate (TTP) are reported. The incorporation of a plasticizer enlarges the crystallization range, decreases the temperature of maximum growth rate and accelerates the kinetics to a considerable extent. The growth-rate parameters are calculated from a least-squares analysis of the experimental data according to the kinetic theory of Hoffman and Lauritzen (1973). From the growth-rate data given here and the overall crystallization kinetics reported previously, concentrations of seeds inducing the crystallization were determined.Anglai

Crystallization of bisphenol-A polycarbonate. II. Melting behavior and equilibrium melting temperature of the plasticized polymer

The melting behavior of bisphenol-A polycarbonate samples plasticized by tritolyl phosphate (TTP), pentaerythritol tetranonanoate (PETN), and trimellitic acid-tridecyloctyl ester (TMDO) has been investigated and discussed on the basis of current theories. Using the Hoffman and Weeks approach modified for finite chain length the variation of the equilibrium melting temperature has been determined as a function of the plasticizer concentration. Extrapolation of these data yields an equilibrium melting temperature of 317 degrees C for the pure polycarbonate of infinite molecular weight. The cryoscopic effect observed is much more pronounced than anticipated on the basis of the Flory-Huggins theory.Anglai

Peek Oligomers - a Model for the Polymer Physical Behavior .3. Nature of Oligomers in the Peek Polymer

Low molecular weight compounds extracted from PEEK have been identified by C-13 NMR, infrared spectroscopy, and size-exclusion chromatography as being cyclic PEEK oligomers. The molecular weight of these cyclic oligomers is larger than 1000. Their wide-angle X-ray scattering powder pattern and crystal habit are totally different from those of the polymer. DSC experiments reveal that the oligomers crystallize in two different crystal types. The nucleation rate of these crystals is rather slow because of the large size of the molecules which have to be incorporated in the nucleus. Consequently, moderate cooling rates give rise to glassy oligomers. A very high T(g) value is observed for the oligomers, in accordance with their low configurational entropy in the amorphous state due to their cyclic structure

Thermal-stability and Crystallization of Poly(aryl Ether Ether Ketone)

The molecular weight distribution of poly(aryl ether ether ketone) (PEEK) has been measured as a function of the melt holding temperature and time in air and in an inert environment. A branching mechanism was observed to occur in the usual melt processing conditions, which was much stronger in air than in vacuum or nitrogen. This degradation mechanism is correlated to a volatile emission observed with thermogravimetric analysis. The influence of the degradation on the PEEK crystallization is discussed. A considerable decrease in crystallization rate is observed associated with the decreased molecular mobility due to the molecular weight increase. and a crystallinity decrease associated with the structural defects introduced along the chains by the branching process. The self-nucleation in PEEK has also been examined through optical microscopy. It was concluded that to get rid of the self-nucleation phenomenon, it is necessary to bring the polymer to temperatures where degradation is already present