Demonstration of isospecific free radical polymerization of acrylate controlled by conformation and chirality of monomer

Abstract

Radical polymerization of lactic acid‐based chiral and achiral methylene dioxolanones, a model for conformationally s‐cis locked acrylate, was carried out with AIBN to demonstrate an isospecific free radical polymerization controlled by chirality and conformation of monomer. Polymerization of the dioxolanones proceeded smoothly without ring opening to give a polymer with moderate molecular weight and 100% of maximum isotacticity. ESR spectrum indicated a twisted conformation of the growing poly(methylene dioxolanone) radical in contrast to an acyclic analogous radical, suggesting a restriction of the free rotation around main chain CαCβ bond of the growing radical center. Chirality as well as the polarity and bulkiness of monomer affected the polymer tacticity, and chiral alkyl substituent would afford a high isotactic polymer, in which higher the enantiomeric excess of the monomer was, higher the isotacticity of the polymer was. While, achiral or polar substituents including dibenzyl and trichloromethyl groups would afford an atactic polymer. In addition, glass transition temperature (Tg) of the resulting polymers was significantly high, ranging from 172.2 to 229.8 °C, and even for an isotactic polymer Tg was as high as 206.8 °C. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 2007–2016

Methylenelactide: vinyl polymerization and spatial reactivity effects

“…Similar findings were reported by Tanaka et al who investigated the polymerization of methylene dioxolanone derivatives yielding predominantly isotactic polymers [15]. Our recently reported spatial dipole–dipole interactions between neighboring lactide units were supported by IR spectroscopy, as the interactions causes two separate carbonyl stretching vibrations.…”

Synthesis, properties and thermal stability of water‐soluble poly(potassium 1‐hydroxyacrylate‐co‐styrene) copolymer

“…The weight‐average molecular weight, radius of gyration and second virial coefficient were measured by Zimm plot. In the Zimm plot Kc /Δ R θ is plotted against sin θ /2 + kc , where k is a constant. The poly(KHA 68 ‐ co ‐St 32 ) copolymer was dissolved in water and plotted for four concentrations and five angles.…”

“…Thus, polymer properties can be anticipated by utilizing the chemical structure of the monomeric units of the polymer . 2‐Isopropyl‐5‐methylene‐1,3‐dioxolan‐4‐one is a monomer and it forms a poly(2‐isopropyl‐5‐methylene‐1,3‐dioxolan‐4‐one) which is soluble in different organic solvents , . Poly(potassium 1‐hydroxyacrylate) (PKHA) is water soluble and is obtained after alkaline hydrolysis of the precursor polymer .…”

Strategy for rational control of stereosequence in free radical polymerization of acrylates

“…1 was synthesized mainly by two steps, that is, cyclization of lactic acid with isobutylaldehyde and following vinylization of resulting cyclic dioxolanone according to the literature . Cyclization, for instance, was carried out by refluxing a mixture of lactic acid 33.8 g (0.375 mol) and isobutylaldehyde 37.8 g (0.524 mol) in n ‐pentane 50 mL for 8 h in the presence of p ‐toluenesufonic acid 1.0 g (5.8 mmol).…”

“…For instance, bromination of the dioxolanone 10.0 g (69.4 mmol) using N‐bromosuccinimide (NBS) 18.2 g (0.102 mol), and AIBN 37.0 mg (0.226 mmol) in CCl 4 100 mL for 4 h followed by dehydrobromination of the brominated dioxolanone 14.1 g (62.6 mmol) with triethylamine 14.1 g (0.139 mol) diluted in benzene 20 mL as reported . After dehydrobromination, crude product was purified by distillation under reduced pressure (bp 52 °C/6 mmHg) to give a colorless liquid in 43.5% yield; [ α ] D = −13.4 and +13.7° (−13.2 and +13.8°) in CHCl 3 for 1S and 1R , respectively. 1 H NMR (CDCl 3 , TMS, ppm): 1.00 (d, J = 6.8 Hz, 3H), 1.01 (d, J = 6.8 Hz, 3H), 2.05 (m, 1H), 4.86 (d, J = 2.7 Hz, 1H), 5.15 (d, J = 2.7 Hz, 1H), 5.59 (d, J = 4.4 Hz, 1H).…”