Ceramic fiber spinning is critical to the manufacture of fibrous monolith ceramics, and understanding the interactions between the polymer matrix and ceramic particle filler is necessary to predict the flow properties of these systems. In this study, poly (methyl methacrylate) (PMMA) was filled with octadecanol-coated St6ber silica, and the rheological behavior of the filled polymers investigated at various filler volume fractions. The rheological behavior of these materials was studied in both dynamic and steady-state experiments. The time required for filled PMMA to reach steady-state behavior under constant shear stress was found to be long, on the order of an hour. The steady-state viscosities increased as expected with filler volume fraction, but did not correlate well with existing models. This is hypothesized to be a result of matrix-filler surface interactions, and will be investigated further in future work.

Interpenetrating polymer networks have been synthesized by performing sol-gel chemistry and conventional organic polymerizations in mixtures of the monomers. The organic polymers were acrylates, and the inorganic phase was SiO2 formed by hydrolysis of orthosilicates. Polymerizations were conducted at a variety of relative rates, and the chemistry was designed to allow different amounts of grafting between the components. The morphology was characterized by transmission electron microscopy and small angle neutron and x-ray scattering. Wide variations in morphology were observed depending on the polymerization conditions, ranging from grossly phase separated to dendritic to finely divided structures (at a 100Å size scale). The phases ranged from mixtures of the two components to relatively pure phases. The interface between the phases ranged from very narrow to relatively broad.

Improving the processing and formability of ceramic components prior to firing (as green bodies) requires an enhanced understanding of how the polymeric binder components function. We report on the role of surface energetics on the structure of the copolymeric monolayers formed via adsorption from solution. Also, results on the effects of surface energetics on the kinetics of the adsorption are reported. A silicon wafer with an oxide layer is used as the surface and adsorption takes place from toluene. Surface energetics are varied by treatment of the oxide surface with a series of silane coupling agents which contain either amine, epoxide, or vinyl functional groups. The block copolymers used consist of relatively short poly(ethylene oxide) (PEO) blocks and much longer polystyrene (PS) blocks. Ellipsometry is used to determine the grafting density, σ (chains/nm2), and Fourier Transform Infrared spectroscopy is used to investigate the copolymer on the surface. It is seen that the time required to reach equilibrium increases as the strength of the interaction between the copolymer and the surface increases. Also, the diblock copolymers appear to obey the scaling laws proposed by Marques and Joanny on all the surfaces studied. ( i.e., σ ∝ 1/NA, when the copolymer is symmetric or moderately symmetric and σ ∝ 1/β2, when the copolymers are asymmetric, where NA is the number of segments of the adsorbing block and β is the ratio of the size of the nonadsorbing block to that of the adsorbing block.)

Ex-PAN carbon fiber surfaces, oxidized to varying degrees by HNO3, have been characterized by NaOH, dye and HCl uptake, ion scattering spectroscopy (ISS), and angleresolved X-ray photoelectron spectroscopy (ARXPS). Subsequent treatments with tetraethylenepentamine to introduce amino groups or epichlorohydrin to introduce epoxy groups have been thoroughly characterized. The efficiency of using these surface functions to bond polymers onto fiber surfaces has been investigated using model anhydrides and isocyanates (for amines) and diols and diamines (for epoxides). The fraction of surface-bound groups which react drops with an increase in molecular size of the species being grafted. Crosslinked elastomeric polyurethane layers with designed modulus values and thicknesses have been bonded to these fibers. Composites have been prepared (epoxy matrices). The impact strengths and interlaminar shear strengths (ILSS) were studied as a function of the interphase modulus and thickness. Impact strengths increased (even at 500–1500 Å thicknesses). ILSS values depend on interphase modulus.

Polymers tethered by one end onto a solid surface are referred to as polymer “brushes”. We consider brushes composed of copolymers that contain both A and B monomers. The A monomers are compatible with the surrounding solvent, while the B sites are solventincompatible. The solvent incompatibility causes the B sites to associate into domains or clusters within the layer. We use Monte Carlo computer simulations and self-consistent field calculations to determine the effect of copolymer architecture on the structure of the polymer brush. In particular, we alter the copolymer sequence distribution (the arrangement of the A and B monomers along the length of the chain) and determine how both the vertical and lateral morphology of the brush are effected by these variations. The results provide guidelines for controlling the size and shape of the B domains, and consequently, the morphology of the tethered layer.

We describe the flow and filtration control imparted to membranes through the adsorption of polymer brushes onto the interior pores. The brushes exhibit a negative Poisson's ratio, i.e. they swell under shear, and as a result behave as sensors and valves controlling the flow and filtration through the pore. The valve-behavior of brushes adsorbed onto cylindrical pores displays the same constant discharge control but also exhibits a critical shear rate for brush swelling.

The use of Scanning Force Microscopy (SFM) to probe wear processes at interfaces is of considerable interest. We present here a simple modification of the SFM which allows us to make highly spatially resolved measurements of conductivity changes produced by abrasion of thin insulating films on metal substrates. The technique is demonstrated on fluorocarbon polymer thin films deposited on stainless steel substrates.

Thin films of polytetrafluoroethylene have been formed by the pulsed-laser deposition technique. The structure of the films was found to be dependent upon the substrate temperature during deposition. At substrate temperatures from room temperature to 200°C the films were determined, by transmission electron microscopy and X-ray diffraction techniques, to be amorphous. Films formed at higher substrate temperatures were found to contain both amorphous and crystalline components. The data for the crystalline component is consistent with it being highly ordered with the long helical molecular chains aligned parallel to the film-substrate interface plane. The maximum amount of crystalline material occurred when the substrate temperature was close to the melting temperature of the polymer.

A novel low temperature process for titanium nitride (TiN) deposition by means of an electron cyclotron resonance (ECR) plasma CVD process was applied to poly(tetrafluoroethylene) (PTFE). The organometallic compound tetrakis(dimethylamido)titanium (TDMAT) introduced into the downstream region of a nitrogen ECR plasma was used as a precursor for TiN deposition at 100°C.

The thin TiN films (thickness 15-30 nm) act as interlayers to activate the electroless deposition of copper followed by an electroplating process. Prior to the deposition of the interlayer, the samples were treated on a biased susceptor with argon ions to enhance the adhesion of the TiN interlayer. This metallization procedure avoids the use of toxic and pollutive etching agents and yields adherent copper layers on PTFE.

The maximum adhesion of the metal film on PTFE was established to be 13 N/mm2. As shown by atomic force microscopy (AFM), TiN grains were formed on the fluoropolymer surface. Film composition was investigated by secondary ionization mass spectrometry (SIMS).

Cu, Ni, and Au were deposited with defined patterns and good adhesion by electroless plating, e-beam evaporation, and sputtering onto Teflon (polytetrafluoroethylene, PTFE), Teflon ET (PTFE-co-ethylene), Teflon FEP (PTFE-co-hexafluoropropylene) and Teflon PFA (PTFE-coperfluoroalkoxy vinyl ether) surfaces. The polymers had been irradiated in a tetramethyl – ammonium hydoxide solution (TMAH) by a Nd:YAG laser at 266 rim and by an excimer laser at 248 nrm prior to the metal deposition process. Both, the treated and virgin polymer surfaces were characterized by x-ray photoelectron spectroscopy (XPS), secondary ion mass spectroscopy (SIMS) and Micro-Raman spectroscopy. The increased metal to polymer adhesion at the interface was found to be due to chemical changes and is in the order Ni > Cu ≅ Au.

UV/ozone cleaning is known to be effective for removing thin organic contaminants, but removal of silicon containing contaminants is questionable. Organo-silicon contaminants, e.g., silicones, can result from a variety of integrated circuit chip and electronic packaging fabrication processes. In this investigation, films of poly(dimethylsiloxane) (PDMS) on silicon substrates, with and without a gold coating, have been used to simulate such contamination up to a thickness of 50 nm. Although treatment consistently reduced the advancing DI water contact angle, in some cases from a value greater than 100° to a value less than 5°, the hydrophilic nature of the treated surfaces was not due to complete contaminant removal, i.e., a significant amount of modified contaminant remained on the surface. High resolution x-ray photoelectron spectroscopy (XPS) in the Si 2p region suggest that O-Si-C bonds in the siloxane, observed prior to treatment, are converted to SiOx, where x is between 1.6 and 2. The time required to reduce the contact angle to a minimum value was greater for the thicker PDMS film samples. Deflection testing was used to evaluate the adhesion of an epoxybased adhesive to intentionally-contaminated silicon chips, before and after UV/ozone treatment. Although PDMS contamination induced loss of adhesion between the chip and the adhesive, complete conversion to silicon oxides by UV/ozone treatment of contaminants having a thickness of 5.0 nm has been demonstrated to restore adhesion to a value equivalent to that of uncontaminated silicon chip surfaces.