1-Methyl-3-methylenecyclobutene (MMCB) and 1,2-dimethylenecyclobutane (DMCB) copolymerized readily with isobutene with aluminum chloride as initiator in methyl chloride solution at temperatures from −95 to −78°C....
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1-Methyl-3-methylenecyclobutene (MMCB) and 1,2-dimethylenecyclobutane (DMCB) copolymerized readily with isobutene with aluminum chloride as initiator in methyl chloride solution at temperatures from −95 to −78°C. No polymers were obtained with methylenecyclobutene (MCB) under similar conditions. The copolymerization of MMCB with isobutene took place through a 1,5-addition reaction while that of DMCB through both 1,2- and 1,4-addition reactions. Large amounts of gel were present in the copolymers obtained from DMCB if the reaction was carried to high conversion. The commonly observed effects of dienes (i.e., rate retardation and molecular weight depression) on cationic copolymerization reactions were observed but to a much higher degree with these small ring dienes. The thermal crosslinking behavior of the resulting copolymers was investigated. In conjunction with the copolymerization studies, homopolymers of MMCB, DMCB, and 3,3-dimethyl-1-isopropylidene-2-methylenecyclobutane (IMCB) were prepared and their chemical structures examined.
A series of α,α‐disubstituted β‐propiolactams (substituted nylon 3 polymers) was prepared from non‐optically active lactams. Their thermal characteristics, densities, and x‐ray fiber diffraction patterns were r...
A series of α,α‐disubstituted β‐propiolactams (substituted nylon 3 polymers) was prepared from non‐optically active lactams. Their thermal characteristics, densities, and x‐ray fiber diffraction patterns were recorded. One of the α‐substituents was always a methyl group while the other was either CH 3 , C 2 H 5 , n ‐C 3 H 7 , or n ‐C 4 H 9 . The melting point for the dimethyl substituted polymer was 268°C; the others were respectively 76, 74, and 72°C. X‐ray fiber diffraction data on all four samples yielded the same fiber repeat of ≈8,4 Å. A minimum energy based conformational analysis for the α,α‐dimethyl derivative indicates that two conformations correspond to this repeat, each of which is a 2 1 helix.
Optically active α-phenyl-ααethyl-β-propiolactone of high optical purity was prepared and polymerized by homogeneous anionic initiation to the isotactic polyester. The racemic and isotactic polymers had apparently...
Optically active α-phenyl-ααethyl-β-propiolactone of high optical purity was prepared and polymerized by homogeneous anionic initiation to the isotactic polyester. The racemic and isotactic polymers had apparently different crystalline properties suggesting that the former may be syndiotactic or may crystallize with unit cells containing both R and S blocks. Similar attempts to prepare α-methyl-α-isopropyl-β-propiolactone of high optical purity were unsuccessful although a partially crystalline polymer was obtained from the racemic monomer.
13 C NMR spectra of isotactic and syndiotactic poly(ethyl α‐chloroacrylate)s and poly(isopropyl α‐chloroacrylate)s were measured in toluene‐ d 8 at 25 MHz. The spectra were analyzed for triad, tetrad and pentad t...
13 C NMR spectra of isotactic and syndiotactic poly(ethyl α‐chloroacrylate)s and poly(isopropyl α‐chloroacrylate)s were measured in toluene‐ d 8 at 25 MHz. The spectra were analyzed for triad, tetrad and pentad tacticities comparing the spectra with the results previously obtained by 1 H NMR spectroscopy. Tetrad tacticities of the polymers were measured from the resonance of the backbone methylene carbon and favorably compared with tetrad values obtained by 1 H NMR. The resonance of the carbonyl carbon showed the peaks corresponding to the tactic triad with a pentad splitting in mm resonance. The triad values obtained from the carbonyl carbon resonance were in good agreement with those calculated from the tetrad values as well as the triad tacticities obtained by 1 H NMR. The quaternary carbon reconances were very complicated because the chemical shift differences for the different tactic triads were of the comparable magnitude with those for the pentads, and a tentative peak assignment was made with the aid of the statistical calculation of pentad values assuming first‐order Markovian statistics for the isotactic polymer and Bernoullian statistics for the syndiotactic polymer.
Under identical conditions of cationic polymerization at low temperature 2‐( p ‐tolyl)‐1‐propene (α, p ‐dimethylstyrene) gave polymers with much higher syndiotactic contents than unsubstituted α‐methylstyrene....
Under identical conditions of cationic polymerization at low temperature 2‐( p ‐tolyl)‐1‐propene (α, p ‐dimethylstyrene) gave polymers with much higher syndiotactic contents than unsubstituted α‐methylstyrene. All samples of poly(α, p ‐dimethylstyrene) were crystalline, but poly(α‐methylstyrene) did not crystallize even at high degrees of stereoregularity. Similarly polymers of p ‐isopropyl‐α‐methylstyrene were crystalline, and the crystalline properties of copolymers of the three monomers were investigated and compared to those of the homopolymers. The rôles of stereoregularity and crystallizability in forming crystalline products were considered. Unter identischen Bedingungen der kationischen polymerisation bei tiefer Temperature lieferte 2‐( p ‐Tolyl)‐1‐propen (α, p ‐Dimethylstyrol) polymere mit höherem syndiotaktischem Gehalt als das unsubstituierte α‐Methylstyrol. Sämtliche Proben von Poly(α, p ‐dimethylstyrol) erwiesen sich als kristallin im Gegensatz zum Poly(α‐methylstyrol), das selbst bei hoher Stereoregularität nicht kristallisierte. Ähnlich erwiesen sich polymere des p ‐Isopropyl‐α‐methylstyrols als kristallin. Die kristallinen Eigenschaften von Copolymeren der drei Monomere wurden untersucht und mit denen der Homopolymere verglichen. Die Rolle der Stereoregularität und der Kristallisierbarkeit bei der Bildung kristalliner Produkte wurde in Betracht gezogen.
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