Understanding the Mechanism of Solvent‐Mediated Adhesion of Vacuum Deposited Au and Pt Thin Films onto PMMA Substrates

Abstract

The adhesion of vapor deposited Au and Pt thin fi lms onto poly(methyl methacrylate) (PMMA) substrates can be signifi cantly enhanced by either spin-casting or vapor-exposure to hydrohalocarbon solvents prior to metal deposition. X-ray photoelectron spectroscopy (XPS) and evolved gas analysis Fourier transform infrared spectroscopy detect residual halogenated solvent at the PMMA surface which chemically activates the surface. Density functional theory (DFT) calculations show that the solvent molecules form a Lewis acid-base adduct with the ester oxygens in PMMA. DFT predicts that the deposited metal atom (M) inserts into the C-halogen (X) bond on either CHCl 3 or CHBr 3 to form a O-M-X interaction. This is consistent with M-X bonding observed in high resolution XPS. A model is proposed in which the bond energy of the C-X bond of the solvent must be weak enough so that it can be cleaved by the metal atom to form a M-X bond. A negative control of PMMA exposed to CHF 3 is shown to have no effect on Au or Pt adhesion since the bond dissociation energy of the C-F bond is stronger than the C-Cl and C-Br bond energy compared to the metal halide bond energies.

Enhancement of Thermal Boundary Conductance of Metal–Polymer System

“…Several studies indicate a large potential for increased Au-PMMA bonding and hence improved TBC through post-treatment of the as-deposited PMMA. Common methods are functionalizing the PMMA surface by plasma treatment [56], UV ozone surface modification [27], organic or halogenated solvents [57,58] and silane bridging [59]. The idea is to treat the PMMA such that chemical bonds can form at the Au-polymer interface.…”

Preparation of a biodegradable poly(vinyl alcohol)–starch composite film and its application in pesticide controlled release

“…The XPS wide scan of all of the drug‐loaded films (presented in Figure ) showed three predominant peaks at binding energies of 529.70, 282.20, and 197.95 eV; these were attributed to O1s, C1s, and Cl2p species, respectively . This denoted that the surface of the PSDMA film was mainly composed of O, C, and Cl, and Cl was assigned to the incorporation of 2,4‐D into the composite films.…”

Significant Enhancement of the Adhesion between Metal Films and Polymer Substrates by UV–Ozone Surface Modification in Nanoscale

“…Referring to the method of Augustine’s group, , a tape test adhesion measurement modified from the ASTM D3359-09 method was used to measure the adhesion of metal films on PMMA substrates. The representative micrographs of PMMA plates containing an 11 × 11 square array of circular metal dots before and after the tape test were shown in Figure S1.…”

“…However, since the polymer surface is nonpolar and has a low wettability, the adhesion of deposited metal films on polymer substrates is normally poor. , This is especially evident for weakly reactive metals, such as Cu, Ag, Au, or Pt . Several methods have been explored to modify the polymer surface to enhance the adhesion, such as plasma treatment using different gases, − irradiation with ion beam or excimer laser, and spin-casting organic solvents. , By these methods, some new polar groups are formed at the polymer surface, and the wettability is increased. Meanwhile, the polymer surface roughness is increased by a few of the aforementioned methods such as plasma treatment, which increases the surface area and also contributes to the improvement in the adhesion …”