Microtacticity of poly(methacrylic esters) obtained by radical polymerization

Abstract

The microtacticity of polymethacrylates prepared by radical initiated polymerization of monomers with side groups of increasing bulkiness is determined by high resolution nuclear magnetic resonance of the corresponding poly(methy1 methacrylates).The syndiotacticity decreases systematically from poty(methy1 methacrylate) to poly-(triethylrnethyl methacrylate) in the series of the saturated polymers.The aromatic polymethacrylates have a lower syndiotacticity than the corresponding saturated polymers and poly(trity1 methacrylate) is the extreme case.The microtacticity of the polymers is undoubtedly determined by the bulkiness and the polarisability of the ester group as well as by specific interaction between the aromatic rings. ZUSAMMENFASSUNG:Die Mikrotaktizitiit von radikalisch polymerisierten Polymethacrylaten, die in der Seitenkette des Monomeren immer grol3ere Gruppen haben, wird durch die hochaufgelosten Kernresonanzspektren der entsprechenden Polymethylmethacrylate bestimmt.Die Syndiotaktizitiit vermindert sich schrittweise von Polymethylmethacrylat bis zu Polytriathylmethylmethacrylat in der Reihe der gesattigten Polymeren. Die aromatischen Polymethacrylate haben eine geringere Syndiotaktizitat als die entsprechenden gesattigten Polymeren. Polytritylmethacrylat stellt den Extremfall dar.Die Mikrotaktizitiit der Polymeren folgt sowohl aus der GroDe und der Polarisierbarkeit der Estergruppe als auch aus der Wirkung, die die aromatischen Ringe aufeinander ausuben.

ESR Study of the Propagating Radical in the Polymerization of MMA in Frozen State

“…(4) The polymer obtained from the radical polymerization of TPMA is stereoregular even at a polymerization temperature of 60°C. 35 These results suggest that the PTPMA radical has more limited conformations than the PMMA radical. If the concept of two conformations is used to explain the ESR spectra, the 5-line spectra of PTPMA radical indicate that this radical consists of mainly a deformed conformation.…”

Highly isotactic polymethacrylates through radical polymerization of methacrylate esters of some ortho‐bridged triaryl carbinols

“…In the examples 1a–c , two of the phenyl groups of the triarylmethanol are linked at the ortho positions through a one‐atom bridge, thus creating a central six‐membered ring. All three compounds were found to polymerize with good yields to afford polymethacrylates with very high degrees of isotacticity (triad mm content >95%) as evidenced by the 1 H NMR spectra of the PMMAs derived from the initial polymers by standard procedures 1, 17. The 1 H NMR signals (CDCl 3 at 20 °C) showed the characteristic pattern of the 2H symmetrical AB quartet centered at δ = 1.83 for the methylene protons as well as the 3H singlet at δ = 1.2 for the α‐methyl protons (Fig.…”

“…Polymethacrylates obtained under radical polymerization in a solution of methacrylic acid esters with various alcohols have been generally found to be mostly atactic, rich in syndiotactic sequences 1. In a few examples of esters with very bulky alcohols, as is the case of the triarylmethyl carbinols,2 the resulting polymers show that diastereoselection operates in favor of isotacticity.…”

Poly(phenyl methacrylate) and poly(1-naphthyl methacrylate) prepared in microemulsions

“…However, the glass‐transition temperature of single chain particles of PMMA was elevated. Polymers of bulkier methacrylic esters formed by free‐radical processes often have tacticities that are different from those of PMMA 9–21. For example, both poly(phenyl methacrylate) (PPhMA) and poly(1‐naphthyl methacrylate) (P‐1‐NM) have more random configurations than PMMA 9–17.…”