Metallocene-mediated synthesis of chain-end functionalized polypropylene and application in PP/clay nanocomposites

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Abstract

This paper summarizes our research in the preparation of chain end functionalized isotactic polypropylene (PP) having a terminal functional group, such as Cl, OH, and NH2. The chemistry involves metallocene-mediated propylene polymerization using rac-Me2Si[2-Me-4-Ph(Ind)] 2ZrCl2/MAO complex in the presence of styrene derivatives (St-f) and hydrogen, which serve as the chain transfer agents. The molecular weight of the resulting PP polymers with a terminal Cl, OH and NH2 group (i.e., PP-t-Cl, PP-t-OH and PP-t-NH2) are inversely proportional to the molar ratio of [St-f]/[propylene]. Despite the extremely low concentration of functional group, the high molecular weight chain end functionalized PP-t-OH and PP-t-NH3+ exhibit a distinctive advantage over other functional PP polymers containing side chain functional groups or long functional blocks. The terminal hydrophilic OH and NH3+ cations, with good mobility and reactivity, effectively hydrogen bond and ion-exchange the cations (Li+, Na+, etc.) located between the clay interlayers, respectively. Such interactions anchor the PP chain to the clay surfaces. On the other hand, the remaining rest of the unperturbed end-tethered high molecular weight PP tail exfoliates the clay layers. This exfoliated structure is maintained even after further mixing of the PP-bearing platelets with pure neat PP polymers.

Original languageEnglish (US)
Pages (from-to)6292-6299
Number of pages8
JournalJournal of Organometallic Chemistry
Volume690
Issue number26
DOIs
StatePublished - Dec 15 2005

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry
  • Materials Chemistry

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