Polybutylene Terephthalate Adhesion on Metals: A Density Functional Theory Investigation (original) (raw)
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DFT and Cluster Model Investigation on the Adhesion of Polyethylene Terephthalate on Metals
e-Journal of Surface Science and Nanotechnology, 2011
We investigate the adhesion mechanism of metal atoms (Al, Cu Ag, Au and Pt) on polyethylene terephthalate (PET) using Density Functional Theory (DFT) and cluster models. The structural geometry of the basic unit of PET is optimized then a metal atom is made to approach this structure at different orientations while calculating the total energy of the system under B3LYP functional. Results show that Al atom binds strongly when oriented linear to C=O at a distance of 1.80Å. Orbital population analysis indicates that the good adhesion of Al at this orientation is due to the interaction of pz orbital of free oxygen in the carbonyl group and py orbital of Al atom. Binding is strongest for Al atom, followed by Pt, Cu, Ag, and Au, in decreasing order of adhesive strength.
Nature of adhesion of condensed organic films on platinum by first-principles simulations
Physical Chemistry Chemical Physics, 2011
Energy decomposition model for the solid organic-metal interfaces. The interface tension Γ inter f ace (J.m −2 ) is calculated from the total electronic energy of the bulk materials (organic crystal and platinum). The formation and relaxation of the (010) surface from the monoclinic phase of the organic crystal requires a surface energy noted E sur f . The change of crystallinity for the relaxed (010) organic surface from monoclinic to fcc phases can be defined as the crystal transition energy E trans . The change of geometry for the organic molecules between the relaxed structure of the (010) surface in the fcc phase and the situation in the relaxed solid organic-metal interface model is associated with the ionic relaxation energy E relax . The change of energy between the frozen structure of the organic phase obtained from the interface with the metal and the relaxed natural (010) organic surface is the deformation energy E de f . The energy difference between the total electronic energy of the relaxed solid organic-metal interface and the references (relaxed clean Pt(111) and natural organic (010) surfaces) is called adhesion energy E adh . The interaction energy E interaction between the frozen organic and metal structures coming from the relaxed interfaces can thus be calculated by subtracting the deformation energy of the organic and the metallic separated systems to the interface energy.
Materials Science and Engineering: A, 2010
We present a combined chemical (auger electron spectroscopy) and microscopic (optical microscopy, scanning electron microscopy and scanning probe microscopy) study of the work of adhesion and delamination mechanisms at interfaces between a glassy polymer (glycol-modified polyethylene terephthalate) and Al covered with different types of surface hydroxides. A clear correlation between the measured work of adhesion and the chemical nature of the Al surface, specifically the hydroxyl coverage and the iso-electric point is found. The magnitude of the work of adhesion points to important contributions from plastic deformation in the glassy polymer for some cases. Delamination is shown to be accompanied by the formation of microscopic shear bands at such interfaces. The non-monotonous stress-strain behaviour of the glassy polymer that gives rise to the shear bands is also shown to lead to peculiar pinning events at the crack front. Evidence indicates that the occurrence of protrusions in the crack front deriving for example from the presence of stress concentrators and crack initiation sites ahead of the front, combined with mode and rate dependence of the local energy release rate along the front may pin the front at positions adjacent to a protrusion. It is believed such microscopic mode-dependent pinning phenomena may be relevant for the adhesion on patterned interfaces.
Polymers
An interfacial adhesion improvement between low-density polyethylene (LDPE) and aluminum (Al) foil is an important challenge in designing multilayered packaging (TetraPak packaging type) due to insufficient inherent adhesion between both untreated materials. Therefore, extra adhesive layers are often used. The hydrophobic character of LDPE is responsible for poor adhesion to Al and can result in delamination. This study deals with the comparative study of the bulk modification of LDPE with various commercially available adhesive promoters with different chemical compositions to increase LDPE’s adhesive characteristics and ensure good adhesion in LDPE/Al laminates. A copolymer of ethylene and methacrylic acid; a terpolymer of ethylene, maleic anhydride, and acrylic ester; or maleated polyethylene (PE) were used as adhesive promoters, and their effect on adhesion improvement of LDPE to Al was investigated. The best adhesion improvement was observed in LDPE-modified samples with maleat...
Progress in Polymer Science, 2009
Most industrially applied polymer resins and composites have low surface free energy and lack polar functional groups on their surface, resulting in inherently poor adhesion properties. A strong research momentum to understand polymer adhesion in the last decade has been motivated by the growing needs of the automotive and aerospace industries for better adhesion of components and surface coatings. This paper reviews the recent research efforts on polymer adhesion with a special focus on adhesion mechanisms. It starts with an introduction to adhesion with explanatory notes on adhesion phenomena. Recent research on the adhesion mechanisms of mechanical coupling, chemical bonding and thermodynamic adhesion is then discussed. The area of adhesion promoters is reviewed with the focus on plasma and chemical treatments, along with direct methods for adhesion measurement. The topics of polymer blends and reactive polymerization are considered and the interactions with adhesion mechanisms are reported. The concluding section provides recommendations regarding future research on the contentious aspects of currently accepted adhesion mechanisms and on strategies for enhancing polymer adhesion strength.
Effect of electron beam treatment on adhesion of Ta/polymeric low-k interface
Applied Physics Letters, 2006
Reliability of the Cu/low-k structure is a serious concern since the metal/dielectric interface is generally weak. The adhesion of the Ta/polyarylene ether interfaces with and without electron beam ͑EB͒ treatment was investigated by four-point bending test, x-ray photoelectron spectroscopy, and density functional theory. Higher adhesion energy ͑G c ͒ was achieved with low-dose EB treatment, attributed to the strong Ta-arene interaction. However, high-dose EB breaks the aromatic rings partially, resulting in fewer available sites for Ta-arene bonding, leading to lower adhesion. It is suggested that the amount of carbon atoms involved in bonding with the metal is the key to improve the Ta/polymer adhesion.
Synthetic Metals, 1993
The interaction between aluminum and ct-(e-diphenyltetradecaheptaene (DP7), asexithienyl (6T), and poly(p-phenylenevinylene) (PPV), respectively have been studied using both X-ray Photoelecu'on Spectroscopy (XPS) and Ultraviolet Photoelectron Spectroscopy (UPS). The UPS valence band spectra, are interpreted with the help of quantum chemical calculations based upon Modified Neglect of Diatumic Overlap (MNDO), Valence Effective Hamitonian (VEH) and ab initio Hartree-Fock methods. DF7 is a model molecule for polyacetylene, while 6T is a model molecule (an oligomer) of polythiophene. The results indicate that aluminum reacts strongly with the surfaces of all of the materials studied. The x-electronic structure of each material was strongly modified. Furthermore, aluminum reacts preferentially with the polyene part of DP7, with the vinylene part of PPV, and with the a-carbons of the thiophene units of 6T.
Chemistry of Materials, 1995
The photolytic addition of thiols or thiolacetic acid to olefinic groups at the surfaces of syndiotadic 1,2-polybutadiene (PBD) provided polymer surfaces bearing sulfide or thioacetate groups. Ethanolysis cleaved these thioacetate groups t o give the corresponding thiols. The product surfaces have been characterized by attenuated total reflectance infrared (ATR-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and contact angles of water. Evaporated films of copper and of gold adhered to surfaces of sulfur-functionalized polymers but not to the unfmctionalized polymers in tape-peel tests. Quantitative adhesion experiments were performed using a 180" peel test with these surface-modified derivatives of PBD (and with the unmodified polymer) heated under pressure against copper foil substrates, and the limiting values of peel strength in these systems were related to the identity of the interfacial functionality in an understandable way. The rate in growth of adhesion was not limited by thermal reconstruction of the polymer surface. Mechanical studies of modified and unmodified samples of PBD indicated that the observed differences in adhesion are not due to changes in the bulk properties of the polymer. 1987,109, 733. (9) Laibinis, P. E.; Whitesides, G. M.; Allara, D. L.; Tao, Y.-T.; Parikh, A. N.; Nuzzo, R. G.
Interaction forces and molecular adhesion between pre-adsorbed poly(ethylene imine) layers
Journal of Colloid and Interface Science, 2006
Interaction forces between pre-adsorbed layers of branched poly(ethylene imine) (PEI) of different molecular mass were studied with the colloidal probe technique, which is based on atomic force microscopy (AFM). During approach, the long-ranged forces between the surfaces are repulsive due to overlap of diffuse layers down to distances of a few nanometers, whereby regulation of the surface charge is observed. The ionic strength dependence of the observed diffuse layer potentials can be rationalized with a surface charge of 2.3 mC/m 2. The forces remain repulsive down to contact, likely due to electro-steric interactions between the PEI layers. These electro-steric forces have a range of a few nanometers and appear to be superposed to the force originating from the overlap of diffuse layers. During retraction of the surfaces, erratic attractive forces are observed due to molecular adhesion events (i.e., bridging adhesion). The frequency of the molecular adhesion events increases with increasing the ionic strength. The force response of the PEI segments is dominated by rubber-like extension profiles. Strong adhesion forces are observed for low molecular mass PEI at short distances directly after separation, while for high molecular mass weaker adhesion forces at larger distances are more common. The work of adhesion was estimated by integrating the retraction force profiles, and it was found to increase with the ionic strength.
Photochemical surface modification of poly(ethylene terephthalate)
Journal of Applied Polymer Science, 1989
To elucidate the role of chemical interactions in the promotion of metal-polymer adhesion, a poly(ethy1ene terephthalate)/copper system was studied. Surface photografting of unsaturated monomers containing different chemical functional groups onto a three-mil poly(ethy1ene terephthalate) f i l m provided a means of examining a variety of copper-polymer interfaces. Initial graft verification was accomplished via contact angle measurements. Adhesion strengths to vacuum-deposited copper were determined using 90" peel tests. Graft analysis, as well as investigation of the interfacial interaction between copper and the grafted moieties, was accomplished using X-ray photoelectron spectroscopy.