Main‐Chain Chirality and Optical Activity in Polymers Consisting of CC Chains

Abstract

Main-chain chirality is the optical activity resulting from the configurational or conformational arrangement in the main chain of a polymer. The chirality of the most important types of structures has been investigated on the basis of systematic considerations of symmetry. This has led to the surprising result that even in polymers derived from 1-substituted or nonsymmetric 1 ,I-disubstituted olefins (the technologically most important polymers) several types of chiral structures exist, which are expected to result in optical activity if a particular enantiomer is favorably formed. By carrying out an asymmetric cyclopolymerization, it has been possible to obtain certain structural types in the form of optically active copolymers or homopolymers (e.g., copolymers of styrene with methyl methacrylate, or even the homopolymer of styrene). Another new group of optically active polymers consists of the atropisomeric helical polyisocyanides, poly(trity1 methacrylates), and polychlorals. Optically active polymers are already used as adsorbents for the chromatographic separation of racemic mixtures. Further applications are likely to emerge.

Reversible conformation-driven order–order transition of peptide-mimic poly(n-alkyl isocyanate) in thin films via selective solvent-annealing

“…As a result, the overall mobility of the PHIC chain induced by toluene vapor is relatively lower. Specifically, the toluene-induced mobility of the polymer backbone is significantly less than that induced by CHCl 3 . Under this circumstance, the alkyl side groups appear to form a smectic A-like ordering rather than a well-defined lattice ordering or full disordering.…”

“…Overall, the CS 2 solvent molecule primarily induces both the rigid amide backbone and the n-hexyl side groups to mobilize in a proper level via favorable interactions in marginal levels; note that the mobility of the polymer backbone induced by CS 2 appears to be greater than that induced in a secondary process by the nonpolar toluene but considerably less than that induced by the polar CHCl 3 . Such cooperative interactions collectively lead the PHIC molecules to have the 8 3 helical conformations and form the HCP structure.…”

“…[1][2][3][4][5][6][7][8] Considerable research efforts have been dedicated to improving the understanding of the conformation and packing of PAICs. Specifically, poly(n-butyl isocyanate) (PBIC) and poly(n-hexyl isocyanate) (PHIC) (Figure 1a) have been thoroughly investigated as representative PAICs.…”

Biomimetic Polymers for Chiral Resolution and Antifreeze Applications

“…Because the right-and left-handed helices are mirror images, if one of the two is preferentially synthesized, the polymer can be optically active. [76][77] Although many stereoregular polymers have a helical conformation in the solid state, most of them cannot maintain a helical conformation in solution because the dynamics of the polymer chain are extremely fast in solution, except for some polymers having an optically-active side group. 78 Therefore, isotactic polystyrene [79][80] and polypropylene 81 prepared with an optically-active catalyst do not show optical activity due to a helical conformation.…”

Advances in synthetic optically active condensation polymers - A review

“…A direct and efficient approach for synthesizing chiral polymers is to introduce chiral elements into the macromolecule backbone or the side chains [6][7][8][9][10][11][12][13][14]. In the history of synthetic polymer chemistry, it seems that one of the most challenging tasks is to construct functional polymeric systems and optically active synthetic polymers that will be as effective as those in living systems [15][16][17][18]. Specially, the synthesis of chiral polymers containing amino acids is a subject of much interest, since a high degree of amino acid functionality can lead to polymers with increased solubility and the ability to form secondary structures.…”