HPLC를 이용한 다양한 합성 고분자의 분리 및 분석
- HPLC를 이용한 다양한 합성 고분자의 분리 및 분석
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- Synthetic polymers are rarely homogeneous chemical species but have multivariate distributions in molecular weight, chemical composition, functionality, and so on. Various interaction chromatographic (IC) techniques as well as size exclusion chromatography (SEC) are employed for the characterization. Also the multiple detection methods each sensitive to a specific molecular characteristic can provide additional information. In this dissertation study, various synthetic polymers were characterized by High Performance Liquid Chromatography (HPLC).
In Chapter I and II, basic working principles of liquid chromatography and MALDI-TOF MS for the molecular characterization of synthetic polymers are briefly reviewed, respectively. Chapter II also includes some practical MALDI-TOF MS methodologies for analysis of synthetic polymers such as matrix selection, sample preparation, etc.
In Chapter III, Poly(dimethyl siloxane) (PDMS) polymers were rigorously characterized. PDMS was characterized by interaction chromatography using C4 i
bonded silica and a mixture of THF/CH3OH as stationary phase and mobile phase, respectively. Under the separation condition, a commercial PDMS with broad molecular weight distribution was successfully fractionated according to molecular weight into fractions with a very narrow molecular weight distribution. The IC separation could be applied to more rigorous characterization of PDMS, modified PDMS and PDMS containing block copolymers.
In Chapter IV, we investigated the side reactions in the anionic ring opening polymerization of poly(butylene oxide) (PBO) by HPLC and MALDI-TOF mass spectrometry. Poly(alkylene oxide) and derivatives are widely used in various scientific and industrial fields. The most extensively employed synthesis technique of polyalkylene oxides (PAO) is anionic ring-opening polymerization. For the anionic ring-opening polymerization of alkylene oxide various side reactions are present. The reason for the side reactions is the relatively high acidity of the alkyl protons of AO leading to different types of termination and chain transfer reactions. In this study, we investigate the side reactions occurring during the anionic ring opening polymerization of butylene oxide at different temperatures by HPLC and MALDI-TOF mass spectrometry. In order to characterize the molecular weight distribution and the end group of the side products precisely by MALDI mass, polymers with target molecular weights of ~5,000 were synthesized under different reaction temperatures. We found that three major side-reactions occur in the anionic polymerization of PBO.
In chapter V, we investigated the effect of the MWD of P3HT to the formation
of the self assembled P3HT and influences of the ordered structure to the organic electronic devices Effect of the molecular weight distribution (MWD) of the poly 3-(hexylthiophene) on the organic electronics was investigated by using the fractionation of the mother polymer. Fractionated F4 P3HT which has narrow MWD was separated from mother P3HT and with these F4 and mother P3HT we fabricated the self assembled P3HT nanowires using marginal solvent for electronic devices such as organic field effect transistors (OFETs) and organic photovoltaics (OPVs). Molecular ordering which is one of the most important factors in organic electronics and nanowire formation could be controlled depending on the value of MWD. Similar sized polymer chains can develop the nanowire formation easily and allow the device properties enhancement based on the molecular ordering increase. Finally improved charge transport contributes to the FET mobility increase about one order and higher OPV efficiency about 3.11% without any post treatments.
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