Stereochemistry and macromolecules: Principles and applications

Abstract

IV, Isotactic, racemic mixture (2)1 Most polymerizations incorporate monomer predominantly in a head-to-tail orientation, as shown in eqn. (1), because of favorable electronic and/or steric factors.

Meso and dl diastereomers: Synthesis and 1H NMR study of the 1,3-diphenylpropane-1,3-diols. An advanced undergraduate project in physical organic chemistry

“…Alternatively, these stereochemical principles could be extended to the study of the tacticity of crystalline polymer systems of the type (-CHR-CH2-CHR-)n, for example, polyfpropylene) or poly(styrene). Then the meso and dl forms studied in this experiment could be considered as corresponding to the elementary units of the isotactic and syndiotactic phases (11).…”

Influence of Tacticity on the Structure Formation of Poly(methacrylic acid) in Langmuir/Langmuir–Blodgett and Thin Films

“…[1] Iso-and syndiotactic polymers are often semi-crystalline, whereas atactic polymers are amorphous as observed in many flexible chain polymers like poly(propylene). [1,5,6] The scenario is different for acrylic polymers such as poly(methyl methacrylate) (PMMA) [7] or poly(acrylic acid) (PAA). [8,9] Even iso-or syndio-tactic rich configurations are still amorphous.…”

Illustrating Catalysis with Interlocking Building Blocks: Correlation between Structure of a Metallocene Catalyst and the Stereoregularity of Polypropylene

“…The propagation of a polymer chain is accomplished by repeating monomer coordination and insertion. Polypropylene can be classified into three categories in terms of tacticity (stereoregularity) (Figure B). − The tacticity of polypropylene originates from the prochirality of propylene (Figure C) . The methyl groups in isotactic polypropylene are arranged on the same side of the polymer backbone, whereas those in the syndiotactic one are arranged on alternate sides of the polymer backbone.…”

“…In atactic polypropylene the methyl groups are oriented randomly along the polymer backbone. The tacticity determines much of the polymer’s mechanical properties . The isotactic and syndiotactic polypropylenes are crystalline materials, while the atactic polypropylene is a viscous liquid .…”