Examination of polymer-polymer miscibility at molecular level by ¹³C CP/MAS/DD nuclear magnetic resonance spectroscopy
by Hoi Sze Lau
M.Phil. Chemical Engineering
xix, 168 leaves : ill. ; 30 cm
The main objective of this study is to investigate the polymer-polymer miscibility and the phase behavior of polymer blends. The information thus obtained should be very useful for the development of high performance engineering polymer blends and alloys....[ Read more ]
The main objective of this study is to investigate the polymer-polymer miscibility and the phase behavior of polymer blends. The information thus obtained should be very useful for the development of high performance engineering polymer blends and alloys.
The experimental techniques employed in this study include thermal analysis, surface characterization, and spectroscopic analysis such as differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR), etc. The experimental probes presented in this study examine the scale of the polymer-polymer miscibility from micro-structure at molecular level to macro-structure of the separated phases.
The importance of studying polymer blends and the relevant applications of blending was demonstrated by investigating four different blend systems, namely, PVC/PMMA, Phenoxy/PCL, Phenoxy/PEOx, and PAA/PVP. These four systems were carefully chosen at the aim of studying the effect of polymer-polymer interactions on the miscibility and the effect of morphology on phase behavior of the blends. A special system of PAA/PVP was chosen to compare the miscibility of the polymer blends and the polymer complexes.
With the help of 13C solid state NMR, we were not only able to judge the miscibility of the above systems, but also able to examine the scale of the miscibility, and hence, to conclude a molecular picture of the polymer blend. In conjunction with the study of the polymer complex, this picture is more vividly described as how intimately the polymer chains can couple together. To incorporate XPS study in polymer complexes can directly give us the complex ratio by elemental analysis.
The major contribution of this work to the academic world is that the miscibility of polymer blends are successfully characterized from the molecular level down to several tens of ÅA. The T1(H) relaxation times report the miscibility at the scale of 200~500 ÅA and T1p(H) relaxation times account for the miscibility at the scale of 10~30 ÅA. The influence of crystallinity on miscibility was also studied with PhenoxyIPCL system.
The nature of this work is fundamental. However, the impact of this work is on both the basic understanding of polymer-polymer miscibility and on the technical supporting side of developing engineering materials.