The characterization of the interfacial interaction between polymeric methylene diphenyl diisocyanate and aluminum: a ToF‐SIMS and XPS study

Abstract

Time of flight secondary ion mass spectrometry (ToF-SIMS) and X-ray photoelectron spectroscopy (XPS) have been employed to study the interfacial interaction between polymeric methylene diphenyl diisocyanate (PMDI) and aluminium produced by the deposition of a thin PMDI layer on the aluminium, in order to improve adhesion and/or abhesion performance.When the PMDI concentration increases, the intensity ratio fragments indicative of the reaction product with water (m/z = 106 u: C 7 H 8 N + ) to that of isocyanate group (m/z = 132 u:C 8 H 6 NO + ) decreases. A very thin MDI layer on oxidised aluminium samples exhibits lower 106/132 ratio than degreased samples as a result of less hydroxide/hydroxyl spices on the surface. This suggests that water reactions occur both at the surface of PMDI and at the PMDI/aluminium interface. The variation of the PMDI chemistry has also been studied by exposing PMDI treated samples to the air for various periods of time (a few hours to 14 days), in order to assess the reaction of the PMDI surface and PMDI/aluminium interface. At the interface, the yield of reaction with water is limited because of the finite amount of hydroxyl groups on the aluminium surface, and the water reaction is completed in a short period of time.However, the PMDI surface continues to react with water from the atmospheric. This methodology was also used to establish the presence of specific interactions at the PMDI/aluminium interface, and a fragment indicative of covalent bond formation between PMDI and aluminium (AlCHNO 3 -) is observed at the interface.2

The characterisation of the interfacial chemistry of adhesion of rigid polyurethane foam to aluminium

“…These peaks are observed from all reaction products and thus it is difficult to identify the cure reaction from the 106/132 ratio 9 . However, the previous paper shows that urea and urethane samples exhibit a high 106/132 ratio 9 . Therefore, increase of the 106/132 cure ratio can imply occurrence of the PMDI reaction with water and/or polyol.…”

“…Figure 2 shows the positive ToF-SIMS spectra in the mass range of m/z = 1-210 u of the raw material samples. From the PMDI sample, a high intensity of a fragment of the isocyanate functional group (m/z = 132 u) is observed, and a fragment of an amine functional group (m/z = 106 u), which originates from the reaction product of PMDI exposed to atmospheric moisture before the analysis, is also observed at low intensity 9 . For the polyol sample, high intensities of oxygen containing fragments such as C 4 which has segregated to the surface during the foil production process.…”

“…Three peaks are observed on the failure surfaces of all foams: the lowest mass peak is Al 2 O 3 -and originates from the aluminium substrate, the highest mass peak is C 7 H 4 N -which comes from PMDI, the middle peak is AlCHNO 4 -which indicates a covalent bond formation between aluminium and PMDI. Details of the peak assignments were described in previous work 9 . By contrast, only Al 2 O 3 -peak is observed on the aluminium foil, and this confirms that the specific bonding is present at the interface between all foams and aluminium.…”

Surface treatment on amorphous InGaZnO4 thin film for single-stranded DNA biosensing

“…8 shows the O 1s spectrum of aIGZO and ITO films with and without OH − pretreatment at a certain sputtering condition. The peaks shown were assigned to OH − and O 2− according to previous reports [49][50][51]. Although the peak profiles of the ITO film changed after OH − treatment, it was not as significantly as that of the aIGZO films.…”

Cyanate ester tethered POSS/BACY nanocomposites for low-k dielectrics

“…[15,[19][20][21] Subsequently, the third peak at 287.5 eV represents the C = O bond of isocyanurate ring. [22] In addition, the characteristic O1s signal was deconvoluted into three peaks (Fig. 5c), the major peak at 531.2 eV corresponds to C-O, small peak at 530 eV is attributed to keto group of isocyanurate, and other one exhibited at 532.0 eV was assigned to the Si-O-Si bond.…”