Abstract
New well-defined telechelic poly(phenyleneoxide)s (PPO's) were synthesized from 4-bromo-2,6-dimethylphenol and bi-phenolic compounds through phase transfer catalyzed aromatic nucleophilic substitution polymerization. Bisphenol–A (BPA), 4,4 ′-biphenol (BP), hydroquinone (HQ) and 2,6-dihydroxynaphthalene (DHN) were employed as telechelic units. The composition analysis by proton-nuclear magnetic resonance ( 1H-NMR) spectroscopy revealed that DHN was highly reactive compared to BPA and HQ, whereas BP was un-reactive in the polymerization process. The number average repeating unit ( n) in telechelic PPO was estimated as n=17–19 and n=17–20 for DHN and BPA (or HQ), respectively. The reactivity of the bi-phenolic in PPO synthesis are confirmed as DHN > HQ ∼ BPA ⩾ BP. The molecular weight determination by gel permeation chromatography (GPC) and viscosity method suggest that the molecular weight of PPO decreased drastically with increasing amount of bi-phenolic units in the feed. The GPC chromatogram of PPO showed a bi-modal distribution, clearly indicative of formation of two different types of molecular weight chains, whereas the telechelic polymers have a mono-modal distribution with a narrow polydispersity. Thermal analysis by differential scanning calorimetry revealed that telechelic polymers are highly amorphous, like PPO, and no crystallization or melting peaks were observed in the heating/cooling cycles.
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