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TY  - THES
AU  - Patterer, Lena
TI  - Chemically-induced changes at interfaces probed by XPS
VL  - 40
PB  - Rheinisch-Westfälische Technische Hochschule Aachen
VL  - Dissertation
CY  - Aachen
M1  - RWTH-2023-09239
T2  - Materials chemistry dissertation
SP  - 1 Online-Ressource : Illustrationen, Diagramme
PY  - 2023
N1  - Veröffentlicht auf dem Publikationsserver der RWTH Aachen University
N1  - Dissertation, Rheinisch-Westfälische Technische Hochschule Aachen, 2023
AB  - The first part of this thesis is dedicated to the systematic investigation of the interfacial bond formation between magnetron-sputtered Ti-Al-O-N thin films deposited onto polycarbonate (PC) and studied by experimental and theoretical methods. Firstly, the bond formation at PC  -  X interfaces (X = Ti, Al, TiAl) was studied by X-ray photoelectron spectroscopy (XPS). Additionally, changes in the chemical state of the polymer were studied systematically by ab initio molecular dynamics (AIMD) simulations of a PC dimer interacting with the corresponding metallic surfaces. These predictions were confirmed by experiments, indicating a higher reactivity at PC  -  Ti interfaces: Ti reacts with all functional groups of PC, forming numerous interfacial C-Ti and (C-O)-Ti bonds, whereas Al exhibits selective reactivity as only (C-O)-Al bonds with the carbonate group are formed. However, integrated crystal orbital Hamilton population (ICOHP) calculations indicate a significantly higher interfacial bond strength for (C-O)-Al bonds compared to (C-O)-Ti and C-Ti bonds (ICOHP differences up to 3.1 eV). By multiplying the experimentally determined relative interfacial bond concentration with the theoretically determined maximum bond strength as an indicator for adhesion, the PC  -  Ti interface exhibits a  1.9 and  1.4 times larger value compared to the PC  -  Al and the PC  -  TiAl interface, respectively. Thus, Ti thin films are the preferential choice as a metallic adhesion layer for PC. Secondly, the interfacial bond formation at PC  -  X interfaces (X = AlN, TiN, (Ti,Al)N) is comparatively investigated by ab initio simulations as well as XPS. The simulations predict significant differences at the interfaces, as N and Ti form bonds with all functional groups of the polymer, while Al reacts selectively only with the carbonate group of pristine PC. In good agreement with simulations, experimental data reveal that the PC  -  AlN and the PC  -  (Ti,Al)N interfaces are mainly defined by interfacial C-N bonds, whereas for PC  -  TiN, the interface formation is also characterized by numerous C-Ti and (C-O) Ti bonds. Bond strength calculations combined with the measured interfacial bond density indicate the strongest interface for PC  -  (Ti,Al)N followed by PC  -  AlN, whereas the weakest is predicted for PC  -  TiN due to its lower density of strong interfacial C-N bonds. This study shows that the employed computational strategy enables prediction of the interfacial bond formation between PC and metal nitrides and that it is reasonable to assume that the research strategy proposed herein can be readily adapted to other organic  -  inorganic interfaces.Thirdly, the bond formation at PC  -  X interfaces (X = Al2O3, TiO2, TiAlO2) is considered. Generally, the predicted bond formation is consistent with the conducted experiments. For all three interfaces, the majority of bonds identified by XPS are (C-O)-metal bonds, whereas C-metal bonds are the minority. Compared to the PC  -  Al2O3 interface, the PC  -  TiO2 and PC  -  TiAlO2 interfaces exhibit a reduction in the measured interfacial bond density by  75 and  65
LB  - PUB:(DE-HGF)11 ; PUB:(DE-HGF)3
DO  - DOI:10.18154/RWTH-2023-09239
UR  - https://publications.rwth-aachen.de/record/969645
ER  -