Fully soluble poly[2-methoxy-5-(2'-ethylhexyl)-oxy)-p-phenylenevinylene] (MEH-PPV) was synthesized by the addition of molecular weight modifiers (chain stopper, Free radical scavengers) to a polymerization system ...Fully soluble poly[2-methoxy-5-(2'-ethylhexyl)-oxy)-p-phenylenevinylene] (MEH-PPV) was synthesized by the addition of molecular weight modifiers (chain stopper, Free radical scavengers) to a polymerization system containing monomer, catalyst and a solvent. These PPV products synthesized in this work were characterized by IR, NMR, UV-visible spectroscopy and GPC. Results show that the M-w of polyphenylvinylene (PPV) can be controlled by the addition of chain stopper (benzyl bromide) and radical inhibitor (2,6-di-tert-butyl-4-methyl phenol). The polymerization mechanism in the presence of these additives was also discussed. A dual mechanism involving carbene for PPV polymerization was proposed.展开更多
Ⅰ. INTRODUCTION It is well known that polypropylene (PP) produced by the Zeigler-Natla catalyst contains a small amount of hydrogen chloride (HCI). We have shown that hydrogen chloride at such a low concentration cou...Ⅰ. INTRODUCTION It is well known that polypropylene (PP) produced by the Zeigler-Natla catalyst contains a small amount of hydrogen chloride (HCI). We have shown that hydrogen chloride at such a low concentration could accelerate the oxidation of PP and destroy the antioxidants and light stabilizers in the commercial product with the decrease of the ageing-resistance prokpertiew. Furthermore, HCI could catalyze and inhibit the thermal oxidation of PP. This duality is known to the hydrogen bromide-polyethylene system, but has not hitherto been reported for the hydrogen chloride-PP system.展开更多
文摘Fully soluble poly[2-methoxy-5-(2'-ethylhexyl)-oxy)-p-phenylenevinylene] (MEH-PPV) was synthesized by the addition of molecular weight modifiers (chain stopper, Free radical scavengers) to a polymerization system containing monomer, catalyst and a solvent. These PPV products synthesized in this work were characterized by IR, NMR, UV-visible spectroscopy and GPC. Results show that the M-w of polyphenylvinylene (PPV) can be controlled by the addition of chain stopper (benzyl bromide) and radical inhibitor (2,6-di-tert-butyl-4-methyl phenol). The polymerization mechanism in the presence of these additives was also discussed. A dual mechanism involving carbene for PPV polymerization was proposed.
文摘Ⅰ. INTRODUCTION It is well known that polypropylene (PP) produced by the Zeigler-Natla catalyst contains a small amount of hydrogen chloride (HCI). We have shown that hydrogen chloride at such a low concentration could accelerate the oxidation of PP and destroy the antioxidants and light stabilizers in the commercial product with the decrease of the ageing-resistance prokpertiew. Furthermore, HCI could catalyze and inhibit the thermal oxidation of PP. This duality is known to the hydrogen bromide-polyethylene system, but has not hitherto been reported for the hydrogen chloride-PP system.
