TY - JOUR A1 - Fahmy, A. A1 - Mix, Renate A1 - Schönhals, Andreas A1 - Friedrich, Jörg Florian T1 - Structure-property relationship of thin plasma deposited poly(allyl alcohol) films N2 - Poly(allyl alcohol) films with a thickness of about 150 nm were deposited by pulse plasma polymerization onto different substrates (inorganic and organic). The structure/property relationships of these samples were studied in dependence on the duty cycle (DC) of the plasma by a broad combination of different techniques and probes. For the first time volume sensitive methods (FTIR and dielectric spectroscopy) are combined with surface analytics by employing XPS for that system. FTIR spectroscopy gives qualitatively the same dependence of the concentration of the OH groups on DC like XPS. The observed differences are discussed considering the different analytical depths of both the methods. The dielectric measurements show that the plasma deposited films are not thermally stable but undergo a post plasma chemical reaction during heating. The results obtained by dielectric spectroscopy are discussed in detail with the data from FTIR and XPS measurements. KW - Allyl alcohol KW - Dielectric properties KW - Plasma polymerization KW - Surface and bulk characterization KW - Thermal stability PY - 2011 DO - https://doi.org/10.1007/s11090-011-9297-0 SN - 0272-4324 VL - 31 IS - 3 SP - 477 EP - 498 PB - Plenum Publ. Corp. CY - New York, NY, USA AN - OPUS4-23671 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Friedrich, Jörg Florian A1 - Wettmarshausen, Sascha A1 - Hanelt, Sven A1 - Mach, Reinhard A1 - Mix, Renate A1 - Zeynalov, Eldar A1 - Meyer-Plath, Asmus T1 - Plasma-chemical bromination of graphitic materials and its use for subsequent functionalization and grafting of organic molecules N2 - Plasma-chemical bromination has been shown to be well-suited for highly selective and efficient C–Br-functionalization of polyolefin surfaces and has now been applied to graphitic materials, including highly oriented pyrolytic graphite (HOPG), natural graphite, carbon nanotubes, and graphitized carbon fibres. In contrast to the radical substitution of hydrogen by bromine at hydrogen-terminated sp3-hybridized carbon, bromination of all-carbon bound sp2-hybridized carbon in graphene requires addition to aromatic double bonds. The related change of sp2 to sp3 hybridization of the carbon atoms involved helps to explain experimental results of a loss in surface planarity on brominated HOPG. Bromine concentrations of up to 50 bromine atoms per 100 C-atoms were achieved in elemental bromine vapour under low-pressure plasma conditions using low-energetic inductively coupled radio-frequency plasma excitation. The time scale of the bromination progress was found to increase with the specific surface area of the material. The results of plasma-chemical bromination are compared to that of wet-chemical electrophilic addition reactions, which achieved 28 Br per 100 C for MWCNT. The resulting C–Br bonds from plasma-chemical processing of graphitic materials were shown to be well-suited for hydroxyl functionalization and for grafting of organic molecules by nucleophilic substitution with 1,6-diaminohexane and (3-aminopropyl)triethoxysilane. PY - 2010 DO - https://doi.org/10.1016/j.carbon.2010.06.054 SN - 0008-6223 SN - 1873-3891 VL - 48 IS - 13 SP - 3884 EP - 3894 PB - Pergamon Press CY - New York, NY AN - OPUS4-21954 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Friedrich, Jörg Florian A1 - Mix, Renate A1 - Kühn, Gerhard T1 - Functional groups bearing plasma homo and copolymer layers as adhesion promoters in metal-polymer composites N2 - Functional groups bearing monomers were pulsed plasma polymerised with a degree of retained functional groups of 55–91%. The following functional groups could be produced at a maximum of: 30 OH, 18 NH2, and 24 COOH per 100 C atoms. A plasma-initiated radical copolymerisation could also be realised using the functional group bearing monomers as a source of functionalities, olefins as ‘chain-extenders’ and dienes as ‘chemical cross-linkers’. The peel strengths of Al layers on such plasma polymers were correlated to the type and density of functional groups. KW - Functional groups KW - Adhesion promoters KW - Metal-polymer composites PY - 2003 DO - https://doi.org/10.1016/S0257-8972(03)00350-5 SN - 0257-8972 VL - 174-175 SP - 811 EP - 815 PB - Elsevier Science CY - Lausanne AN - OPUS4-2703 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Friedrich, Jörg Florian A1 - Kühn, Gerhard A1 - Mix, Renate A1 - Fritz, Andreas A1 - Schönhals, Andreas T1 - Polymer surface modification with monofunctional groups of variable types and densities N2 - The retention of chemical structure and functional groups during pulsed plasma polymerization was used for producing adhesion-promoting plasma polymer layers with high concentrations of exclusively one kind of functional groups, such as OH, NH2, or COOH. The maximum content of functional groups was 31 OH using allyl alcohol, 18 NH2 using allylamine, or 24 COOH per 100 C atoms using acrylic acid. To vary the density of functional groups, chemical co-polymerization with ethylene as 'chain-extending' co-monomer, or butadiene as 'chemical crosslinker' was initiated in the pulsed plasma. The composition of these co-polymers was investigated by XPS and IR spectroscopy. The concentrations of functional groups were measured by derivatizing with fluorine-containing reagents and using XPS. A set of plasma parameters was found to be a good compromise between a high number of functional groups and complete insolubility in water, ethanol or THF,which is needed for further chemical processing. Here, these monotype-functionalized surfaces were used in metal-polymer systems as adhesion-promoting interlayers to examine the influence of type and density of functional groups on adhesion. As expected, COOH- and OH-group-terminated interlayers showed maximum peel strengths to evaporated aluminium layers. The adhesion increased linearly with the number of OH groups to a maximum at about 27 OH per 100 C atoms. Higher concentrations of OH groups did not increase the peel strength further. KW - Co-polymers KW - Adhesion-promoting interlayers KW - Metal-polymer systems PY - 2003 DO - https://doi.org/10.1163/156856103322396695 SN - 0169-4243 SN - 1568-5616 VL - 17 IS - 12 SP - 1591 EP - 1617 PB - VNU Science Press CY - Utrecht AN - OPUS4-2704 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Friedrich, Jörg Florian A1 - Kühn, Gerhard A1 - Mix, Renate A1 - Unger, Wolfgang T1 - Formation of Plasma Polymer Layers with Functional Groups of Different Type and Density at Polymer Surfaces and their Interaction with Al Atoms N2 - Monotype functionalizations with different types of functional groups (OH, NH2, COOH) on polypropylene and poly(tetrafluoroethylene) surfaces were synthesized using pulsed plasma-initiated homo- or copolymerization of functional group-carrying monomers. The maximum concentrations of functional groups were 31 OH, 18 NH2 or 24 COOH groups per 100 C atoms using allyl alcohol, allylamine or acrylic acid respectively as the monomer. The measured peel strengths of aluminium deposits increased linearly with the concentration of functional groups. Near the maximum concentration of OH (>27 OH/100 C atoms) or at moderate concentrations of COOH groups (>10 COOH/100 C atoms), constant (maximum) peel strengths were measured due to the mechanical collapse of one component in the composite (cohesive failure). Interface failures in Al-PP composites were found with COOH, NH2 and OH groups and cohesive failures were seen when higher concentrations of COOH groups were applied (>10 COOH/100 C atoms). PY - 2004 DO - https://doi.org/10.1002/ppap.200400008 SN - 1612-8850 SN - 1612-8869 VL - 1 IS - 1 SP - 28 EP - 50 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-4707 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Friedrich, Jörg Florian A1 - Mix, Renate A1 - Kühn, Gerhard T1 - Adhesion of metals to plasma-induced functional groups at polymer surfaces N2 - The peel strength of aluminium to polypropylene and poly(tetrafluoroethylene) was determined in dependence on the type and the concentration of functional groups on the polymer surface. For this purpose the polymer surface was equipped with monotype functional groups. The first method to produce monotype functionalized surfaces was an introduction of O functional groups using an oxygen plasma treatment and converting these groups to OH groups applying a wet chemical reduction. In result of this two-step treatment the hydroxyl group concentration at the polymer surface could be increased from 3–4 to 10–14 OH groups/100 C atoms. The second method consists in the deposition of a 150 nm adhesion-promoting layer of plasmapolymers or copolymers onto the polymer surface using the pulsed plasma technique. For that purpose functional groups carrying monomers as allyl alcohol, allylamine and acrylic acid were used. Applying the plasma-initiated copolymerization and using neutral “monomers” like ethylene or butadiene the concentration of the functional groups was varied. A correlation of peel strength with the ability of forming chemical interactions between Al atoms and functional groups was found: COOH > OH >> NH2 > H(CH2–CH2). KW - Peel strength KW - Aluminium KW - Polypropylene KW - Poly(tetrafluoroethylene) KW - Pulsed plasma KW - Allyl alcohol KW - Allylamine KW - Acrylic acid KW - Plasma surface treatment KW - Adhesion PY - 2005 SN - 0257-8972 VL - 200 IS - 1-4 SP - 565 EP - 568 PB - Elsevier Science CY - Lausanne AN - OPUS4-10897 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mix, Renate A1 - Gähde, J. A1 - Goering, Harald A1 - Schulz, Günter T1 - Segmented polyurethanes with 4,4-bis-(6-hydroxyhexoxy)biphenyl as chain extender - Part 2. Synthesis and properties of MDI-polyurethanes in comparison with 2,4-TDI-polyurethanes N2 - Linear segmented polyurethanes based on poly(butylene adipate)s (PBA) of different molecular weight (Mn 2000, 1000, and 600), 4,4-diphenylmethane diisocyanate (MDI) and the mesogenic diol 4,4-bis-(6-hydroxyhexoxy)biphenyl (BHHBP) as well as the unsegmented polyurethane consisting of MDI/BHHBP units have been synthesized and characterized by elemental analysis, 13C-NMR and SEC. The thermal behavior and the morphology were studied by DSC, polarizing microscopy, and DMA. The properties of the MDI-polyurethanes were discussed in relation to the BHHBP chain extended 2,4-TDI-polyurethanes and common 1,4-butanediol chain-extended MDI products. MDI polyurethanes based on PBA (Mn 2000) exhibit a glass transition temperature Tg of about -40°C independent of the hard segment content up to 50% hard segments. At higher hard segment contents increasing Tgs were observed. Polyurethanes, based on the shorter polyester soft segments PBA (Mn 1000 or 600), reveal an increase in the glass transition temperatures with growing hard segment content. The thermal transitions caused by melting of the MDI/BHHBP hard segment domains are found at 50 K higher temperatures in comparison with the analogous TDI products with mesogenic BHHBP/TDI hard segments. Shortening of the PBA chain length causes a shift of the thermal transitions to lower temperatures. Polarizing microscopy experiments indicate that liquid crystalline behavior is influenced by both the content of mesogenic hard segments and the chain length of the polyester. © 1996 John Wiley & Sons, Inc. PY - 1996 DO - https://doi.org/10.1002/(SICI)1099-0518(19960115)34:1<33::AID-POLA3>3.0.CO;2-4 SN - 0360-6376 SN - 0887-624X VL - 34 IS - 1 SP - 33 EP - 44 PB - Wiley CY - Hoboken, NJ AN - OPUS4-2151 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gähde, J. A1 - Mix, Renate A1 - Krüger, Ralph-Peter A1 - Goering, Harald A1 - Funke, W. A1 - Hermann, U. T1 - Adherence of Liquid Crystalline TDI-Polyurethanes to Steel KW - Main-chain liquid crystalline polyurethanes KW - Primer on steel KW - Pull-off test KW - Wet adhesion of alkyd melamine resin KW - Mesogenic unit KW - Glass transition temperature KW - Hard segments KW - Soft segments PY - 1996 SN - 0021-8464 SN - 1545-5823 VL - 58 SP - 243 EP - 251 PB - Gordon & Breach CY - New York, NY AN - OPUS4-2152 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Yin, Huajie A1 - Mix, Renate A1 - Friedrich, Jörg Florian T1 - Influence of differently structured aluminium-polypropylene interfaces on adhesion N2 - Polar groups were introduced on polypropylene surfaces for increasing the surface energy and the peel strength to evaporated aluminium layers. Three kinds of plasma processes were used for introducing such functional groups to polyolefin surfaces: low-pressure radio-frequency (RF) O2 plasma exposure, atmospheric-pressure dielectric-barrier discharge (DBD) treatment in air, and the deposition of allylamine plasma polymer. The amino groups of the allylamine plasma polymer were also used as anchoring points for chemical introduction of covalently bonded spacer molecules equipped with reactive endgroups. Thus, silanol endgroups of a covalently bonded spacer were able to interact with the evaporated metal layer. The Al-PP composites achieved a maximal peel strength of 470 N/m by exposing the polymer to the lowpressure O2 plasma and 500 N/m on exposure to the atmospheric DBD plasma. After allylamine plasma polymerization and grafting of spacers, the peel strength was usually higher than 1500 N/m and the composites could not be peeled. KW - Polypropylene KW - Low-pressure RF oxygen plasma KW - Dielectric barrier discharge (DBD) KW - Pulsed plasma polymerization KW - Surface wettability KW - Peel strength PY - 2011 DO - https://doi.org/10.1163/016942410X511132 SN - 0169-4243 SN - 1568-5616 VL - 25 IS - 8 SP - 799 EP - 818 PB - VNU Science Press CY - Utrecht AN - OPUS4-23990 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fahmy, A. A1 - Mix, Renate A1 - Schönhals, Andreas A1 - Friedrich, Jörg Florian T1 - Surface and bulk structure of thin spin coated and plasma-polymerized polystyrene films N2 - Polystyrene (PS) spin coated thin films were modified by O2 and Ar plasma as well as by UV irradiation treatments. The modified PS samples were compared with plasma polymerized and commercial polystyrene. The effects of plasma (O2 and Ar) and UV irradiation treatments on the surface and the bulk properties of the polymer layers were discussed. The surface properties were evaluated by X-ray Photoelectron Spectroscopy and Contact angle measurements and the bulk properties were investigated by FTIR and dielectric relaxation spectroscopy. As a result only one second treatment time was sufficient to modify the surface. However, this study was also dedicated to understand the effect of plasma and plasma irradiation on the deposited layers of plasma polymers. The dielectric measurements showed that the plasma deposited films were not thermally stable and underwent an undesired post-plasma chemical oxidation. KW - Surface and bulk characterization KW - Plasma polymerization KW - Polystyrene KW - Surface modification KW - Thermal stability KW - Plasma polymers PY - 2012 DO - https://doi.org/10.1007/s11090-012-9372-1 SN - 0272-4324 VL - 32 IS - 4 SP - 767 EP - 780 PB - Plenum Publ. Corp. CY - New York, NY, USA AN - OPUS4-26264 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -