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Studies of some poly (phenylene vinylene) derivatives and their composites : synthesis and characterization
Author
Wang, Yu-Ming
Supervisor
Gan, Leong Huat
Abstract
This thesis describes the study of some new poly(phenylene vinylene)(PPV) derivatives and their crosslinked rubber-silica composites. Chapter 1 gives a literature review of PPV derivatives and their electrical-optical properties. Chapter 2 describes the synthesis of some new PPV derivatives and their photoluminescent (PL) and excellent electroluminescent (EL) properties. 1,4-Di-a-bromomethyl-2,3,5,6- tetrafluorobenzene has been successfully synthesized. The compound has a melting point of 126oC and the structure is carefully characterized by 1H NMR, GC/MS, HPLC and X-ray diffraction methods. The compound is used as the monomer for the preparation of poly(2,3,5,6-tetra-fluoro-phenylene vinylene)(PTFPV) through the chlorine precursor route (CPR). The conjugated polymer shows good PL and EL properties. Another new PPV derivative, poly (2,3,5,6-tetrabromo-1,4-phenylene vinylene) (PTBrPV) has also been synthesized. However, the polymer has very poor PL properties. Poly(2,5-dimethoxy-1,4-phenylene vinylene)(PDMoPV) are prepared via both the CPR and Wessling methods. The PDMoPV prepared via Wessling method fluoresces at a longer wavelength with the maximum at 540 nm, while the fluorescence of the PDMoPV via CPR has blue shifted with the maximum at 505 nm. P(TFPV-co-DMoPV) copolymers are also successfully obtained. Single layer LEDs have been fabricated using the polymers prepared. The ITO/PTFPV/AI, ITO/PDMoPV (via Wessling method)/A1 and ITO/PDMoPV (via CPR)/A1 and ITO/P(TFPV-co-DMoPV)/A1 devices are found to emit blue-green light at very low turn-on voltages of 4, 7, 4 and 8 V respectively.
In Chapter 3, the synthesis of a new rubber/silica hybrid material SIS-g-HEMA/silica through the sol-gel process is described. The effects of various factors such as the amounts of DBSA and TEOS, hydrolysis temperature and the curing time on the morphology are studies in detail.
In Chapter 4, the incorporation of PDMoPV into four new rubber-silica matrices prepared, i.e. SIS-g-HEMA/silica, SIS-g-HEMA/silica, SIS-g-AA/silica, SBS-g-HEMA/silica, and SBS-g-AA/silica are described and the fluorescent properties are also studies. Considerable blue shift for the fluorescence of PDMoPV in the rubber/silica composites is observed. These photo-luminescence composite materials are flexible and thus may have some advantages over other rigid PL materials.
In Chapter 3, the synthesis of a new rubber/silica hybrid material SIS-g-HEMA/silica through the sol-gel process is described. The effects of various factors such as the amounts of DBSA and TEOS, hydrolysis temperature and the curing time on the morphology are studies in detail.
In Chapter 4, the incorporation of PDMoPV into four new rubber-silica matrices prepared, i.e. SIS-g-HEMA/silica, SIS-g-HEMA/silica, SIS-g-AA/silica, SBS-g-HEMA/silica, and SBS-g-AA/silica are described and the fluorescent properties are also studies. Considerable blue shift for the fluorescence of PDMoPV in the rubber/silica composites is observed. These photo-luminescence composite materials are flexible and thus may have some advantages over other rigid PL materials.
Date Issued
1999
Call Number
QD381 Wan
Date Submitted
1999