Al~traet--Copolymers of 4-methylpentene-1 and styrene were prepared (TiCla-AliBu3, 70 ยฐ) and their structure investigated. Monomer reactivity ratios calculated from the copolymer compositions were found to be 3"92 and 0"98. Comparison of the i.r.-spectra of copolymers thus prepared and of isotactic homopolymers (poly-4-methylpentene-1 and polystyrene) allowed some estimation of monomer distribution in copolyrners of different composition; this estimation for styrene units was based on band intensities at 565, 1084 and 985 cm -1, and for 4-methylpentene-1 units on band intensity at 997 era-t. These data show the copolyrners of 4-methylpentene-I and styrene to have random structure, and to be described by statistic relationships corresponding to rlr2 ',, 1. Possible reasons for discrepancies between r~r~-values from compositional studies and those obtained from i.r.-data are discussed.
THERE HAVE been reports on copolymerization of 4-methylpentene-I (4MP1) and styrene using Ziegler-Natta catalysts. (1 .') However, the technique used by the authors did not allow any estimate of monomer isomerization during the process (for isomerization of 4MP1 occurring over complex organometallic catalysts see(S)); apparently the structure of the copolymers was not adequately studied.
Therefore, we have undertaken a thorough study of 4MP1 copolymerization with styrene. The reaction mixture composition during the process was followed by GLC (gas-liquid chromatography); the polymer composition and structure were studied by i.r.-spectroscopy. EXPERIMENTAL 4MPI was distilled over Na with a column of a 100 theoretical plates and then stored in a Sohlenke vessel over Na wire and under argon. Styrene was washed with 10~o aq. NaOH, water, and then distilled over CaH~ under vacuum. Benzene was purified as described in (4) and stored over Na and under argon, iBu3Al was distilled under vacuum at 62 ยฐ. TiCI3 used was of the violet modification (Stauffer, ATR-grade).
Copolymerization was carried out in sealed tubes or in a reaction vessel which permitted sampling.
Reaction mixture composition was determined with a LKhM-SM chromatograph. The column (5 m) was packed with squalane on celite 545; operating temperature was 116ยฐ; helium was the carder gas with flow-rate 60 ml/min.
Cyclohexane was used as internal standard reference. Compositions of copolymers were determined chromatographically and spectroscopically from the ratio of optical densities of the band at 1388 ยขm-t (absorption band of the methyl group in 4MPI units) and the band at 1603 cm-t (benzene 487