Alternating copolymerization through the complexes of conjugated vinyl monomers–alkylaluminum halides

Abstract

A vinyl monomer that has the nitrile or carbonyl group conjugated to the CC double bond, such as acrylonitrile, methyl acrylate, and methyl methacrylate, forms a complex with an alkylaluminum halide, and the complex reacts spontaneously with a hydrocarbon monomer such as styrene, propylene, or ethylene, giving a high molecular weight copolymer. The copolymers always contain the two monomer units in 1:1 ratio. Thus styrene, copolymerized with methyl acrylate or methyl methacrylate in the presence of ethylaluminum sesquichloride in homogeneous toluene solution, gives such an equimolar copolymer regardless of the initial monomer compositions. The NMR spectra of these copolymers are distinctly different from those of the equimolar copolymers obtained with azobisisobutyronitrile as initiator and have simpler and well separated patterns. The copolymers and the corresponding radical copolymers appear to be amorphous, judged by their x‐ray diffraction patterns and their differential thermal analyses. Their infrared spectra resemble each other very closely. Hence, the difference in the NMR spectra may be ascribed to the matter of the sequence distribution. The infrared spectrum of ethylene–methyl acrylate copolymer shows no absorption near 720 cm.−1 due to the methylene sequence arising from ethylene–ethylene linkage. These experimental data lead to the inference that the equimolar copolymers obtained in this work may have an alternating sequence.

Electron-Withdrawing Enhancement of Monomers Complexed with Alkylaluminum Halides

“…Refering to the Q-e scheme, the following relations hold: Then, r 1 r 2 =exp{-(e 1 -e 2 h} (3) From eq 3, it is recognized that as for the alternating copolymer the difference of e-values between two monomers is required to be large. Therefore, it may be theoretically understood that if the e-value of a monomer is enhanced by forming a complex, the alternating tendency is to be raised.…”

Radical/cation transformation polymerization and its application to the preparation of block copolymers

“…Accordingly, the radical polymerization is one of the most well-refined research fields in polymer synthesis (Refs. [1][2][3][4][5]. Sequence and structure controls are the most important problems in the polymer syntheses.…”

Hypochromic Effects in UV Spectra of Polymers in Solution

“…The alternating ST-MMA copolymer (SM-AL) was polymerized at -78°C with Al(C2H 5)i_ 5 • Clu in toluene according to the method given by Hirooka, et al 11 The block copolymer (SMBlock) was kindly provided by Dr. T. FukudaTanaka, University of Kyoto, the preparation and characterization of which are given in ref 10. Random ST-MMA copolymer samples with different ST contents (coded as SM-series) were supplied by the courtesy of Dr. R. J. Briissau, BASF AG., Ludwigshafen.…”