Anionic Copolymerizations of 1,1-Diphenylethylene with o- and p-Methoxystyrene

Abstract

ABSTRACT:Anionic copolymerizations of 1,1-diphenylethylene (OPE) with o-and pmethoxystyrene (o-and p-MeOSt) were investigated with n-butyllithium (n-BuLi) and other anionic initiators. In THF, alternating copolymers ofDPE with o-andp-MeOSt were obtained. In aromatic hydrocarbons, the copolymerization of DPE and o-MeOSt with n-BuLi gave a polymer having higher o-MeOSt content, while an almost alternating copolymer was obtained in the copolymerization of DPE and p-MeOSt. The NMR spectra of the alternating copolymers of DPE with o-and p-MeOSt showed the splittings due to the tactic difference with respect to the methoxy group. The latter alternating copolymer was shown by polarized light and X-ray examinations to be crystalline.In earlier studies anionic coplymerizations of various monomer pairs were carried out to obtain information on the reactivities of the monomers and to form new polymers, 1 -5 some of which were alternating. On the other hand, o-methoxystyrene (o-MeOSt) formed a crystalline isotactic polymer in a nonpolar solvent by means of nbutyllithium (n-BuLi), but formed an atactic polymer in tetrahydrofuran (THF) 6 It was supposed that the driving force behind the formation of the isotactic poly (o-methoxystyrene) (P-o-MeOSt) was the interactions of the ether oxygens of the monomer and/or the polymer with lithium counter-ion, and the interactions were diminished in a solvent of higher solvating power such as THF.It is probable that the interaction stated above may occur in the copolymerization of o-MeOSt and 1,1-diphenylethylene (OPE), and greatly affect the reactivity. In the present paper, besides the copolymerization of these two monomers, the copolymerization of p-methoxystyrene (pMeOSt) and OPE is also studied in order to know the properties of the copolymer and the reactivity of the isomer. Materials o-MeOSt EXPERIMENTALThis was synthesized by dehydration of methyl-(2-methoxyphenyl) carbinol over acid potassium sulfate at 220--230°C, 6 and then the crude product was fractionally distilled. The monomer was dried over lithium aluminum hydride in an atmosphere of dry nitrogen, from whence it was redistilled, bp 80--81 °C (10 mmHg), nD 20 1.5605. No impurity was detected by gas chromatography or NMR spectroscopy.p-MeOSt p-MeOSt was obtained by distillation of methyl-(4-methoxyphenyl)carbinol in the presence of a small amount of hydrochloric acid. The monomer purified by distillation was dried over lithium aluminum hydride and redistilled, bp 85°C (13 mmHg), nD 20 1.5615. No impurity was detected by gas chromatography or NMR spectroscopy. DPE This was prepared by dehydration of methyldiphenylcarbinol with sulfuric acid. 7 The monomer was first stirred with Na-K alloy, and then n-BuLi inn-heptane was added until a red coloration appeared. The colored solution was fractionally distilled under dry nitrogen. The fraction . 20of bp 97-98°C (1.5 mmHg) was collected; nD 1.6085. TIIFThe solvent refluxed over lithium aluminum hydride was distilled onto benzophenone and 13

Monomer Sequence Control via Living Anionic Copolymerization: Synthesis of Alternating, Statistical, and Telechelic Copolymers and Sequence Analysis by MALDI ToF Mass Spectrometry

“…However, Yuki et al first reported in 1967 that DPE could be used in an anionic copolymerization with other monomers. [22][23][24][25][26][27] Furthermore, depending on the feed ratio, solvent and co-monomer, apparently perfect alternating copolymers could be prepared provided that the rate constant for cross-propagation to DPE (M 2 ) is significantly higher than the rate constant for self-propagation of the non-DPE monomer (M 1 ) i.e. k 12 << k 11 .…”

“…[22][23][24][25][26][27] Of particular interest for living anionic copolymerizations is the monomer 1,1-diphenylethylene (DPE). DPE is unable to form a homopolymer due to the steric bulk of the monomer although it has been reported 28 that the formation of dimers of DPE can occur following the initiation with n-butyllithium where there is a large excess of DPE with respect to lithium.…”

“…45 Herein sequence-controlled copolymerizations containing DPE and the synthesis of telechelic copolymers using a DPE derivative in a single one-step copolymerization are investigated. Early examples of alternating copolymers (based upon DPE) prepared by living anionic polymerization were reported nearly half a century ago [22][23][24][25][26][27] . In the 1960's NMR was the state-of-the-art analytical technique and was used in combination with infrared spectroscopy and reaction yields to analyze the composition of the resulting copolymers.…”

Stereospecific Polymerization of o-Methoxy-α-methylstyrene

“…It has been reported that o-methoxystyrene ( o-MeOSt) formed a crystalline isotactic polymer in a nonpolar solvent by n-BuLi, 2 and that the ether group of the monomer greatly affected the reactivity of the monomer. 3 In the present study, o-MeO-a-MeSt was polymerized under various reaction conditions, and the stereoregularity of the polymer was determined by NMR spectroscropy in comparison with that of poly-(a-MeSt). The results obtained were correlated with those of the stereospecific polymerization of a-MeSt which had been investigated by several groups.…”

Crystallinity in equimolar highly alternating butadiene–methyl methacrylate copolymers

“…In those instances (15,16) where other equimolar alternating copolymers have been reported to be crystalline, the copolymers either contained symmetrical repeating units or else isomorphism was possible. Neither of these factors seems to account for the occurrence of crystallinity in alternating copolymers of butadiene with methyl methacrylate or methacrylonitrile.…”