Synthesis of Chain-End Functionalized PP and Applications in Exfoliated PP/Clay Nanocomposites

This paper summarizes our research to the preparation of chain‐end functionalized isotactic polypropylene (i‐PP) having a terminal functional group, such as an OH and an NH2. The chemistry involves metallocene‐mediated propylene polymerization using the rac‐Me2Si[2‐Me‐4‐Ph(Ind)]2ZrCl2/MAO complex in...

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Bibliographic Details
Published in:Macromolecular symposia. 2005-05, Vol.225 (1), p.113-128
Main Authors: Wang, Z.M., Han, H., Chung, T.C.
Format: Article
Language:English
Subjects:
Cations
Chains (polymeric)
Clay (material)
Exfoliation
Functional groups
functionalization
metallocene
Molecular weight
nanocomposite
polypropylene
Polypropylenes
PP/clay composite
Terminals
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Summary:This paper summarizes our research to the preparation of chain‐end functionalized isotactic polypropylene (i‐PP) having a terminal functional group, such as an OH and an NH2. The chemistry involves metallocene‐mediated propylene polymerization using the 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 i‐PP polymers with terminal OH or NH2 groups (i.e., 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 groups, the high molecular weight NH3+‐terminated PP (PP‐t‐NH3+) exhibits a distinctive advantage over other functional PP polymers containing side chain functional groups or long functional blocks. The terminal hydrophilic NH3+ cation, with good mobility and reactivity, effectively ion‐exchanges the cations (Li+, Na+, etc.) located between the clay interlayers, and anchors 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.
ISSN:1022-1360
1521-3900
DOI:10.1002/masy.200550710