Abstract
Poly(methacrylic acid) (PMAA) with a two-fold helical axis was synthesized from sodium methacrylate in the presence of chitosans. The polymer chain formed a two-fold helix with a syndiotactic conformation, in which the sequence of the bond rotation was (TTGG)2 (T- trans, G- gauche). The PMAA was optically active to produce a negative Cotton effect in the UV region. The crystalline powder of PMAA was found to form an orthorhombic lattice with a = 7.94, b = 6.51, and c = 7.99 Å (identical period), of which the space group was determined to be P2221. The astonishing crystallinity of this compound comes from template polymerization with a chiral strand of chitosan. Electronic structures of stereoregular PMAA isomers are also discussed from the perspective of band theory and spectroscopic data. The helical sense was determined to be left-handed by circular dichroism and quantum-chemical calculations, which followed the helical rule for C2 molecules.
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