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Non‐covalent chemical modification of crown ether side‐chain polymethacrylates with a secondary ammonium salt: a family of new polypseudorotaxanes
Author(s) -
Yamaguchi Nori,
Gibson Harry W.
Publication year - 2000
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/(sici)1521-3935(20000401)201:7<815::aid-macp815>3.0.co;2-#
Subject(s) - side chain , polymer chemistry , covalent bond , salt (chemistry) , crown ether , ammonium , chemistry , ether , chemical modification , crown (dentistry) , materials science , organic chemistry , polymer , composite material , ion
Here we report syntheses of copolymeric polymethacrylates ( 5 ) bearing dibenzo‐24‐crown‐8 (DB24C8) moieties and their non‐covalent chemical modification with dibenzylammonium hexafluorophosphate ( 7 ) to form side‐chain polypseudorotaxanes. The complexation process, primarily driven by hydrogen bonding and π ‐stacking interactions, was investigated in solution with 1 H NMR spectroscopy. By the use of Scatchard and Hill plots it was shown that this system is anticooperative, with a Hill coefficient, n H ≈ 0.45; that is, in addition to the usual entropic effects associated with multiple binding sites, the addition of subsequent ligands to an already complexed macromolecule is retarded. Thus, the more crown moieties per macromolecule or the higher the fraction of complexed sites, the lower the effective macroscopic binding or association constant. Films of the side‐chain polypseudorotaxanes showed significant increases in T g compared to the parent polymers. The effects of pseudorotaxane formation on surface morphology of films are also reported.