Copolymerization of various isocyanates with ethylene oxide

Abstract

Copolymerization of various monoisocyanates with ethylene oxide was attempted in relation to the alternate copolymerization of phenyl isocyanate with ethylene oxide by tri ethylaluminum catalyst. It was found that aliphatic and alicyclic isocyanates are not copolymerizable at all while many of aromatic isocyanates give the copolymer. The copolymer obtained was supposed to be alternate one. As to the substituted phenyl isocyanates, it was shown that ortho-substituted isocyanates give the copolymer in high yield, with one exception: 0-anisyl isocyanate. There is no relation between the copolymer yields and HAM-METT'S substituent constants. These results suggest that triethylaluminum may preferentially coordinate with the oxygen atom rather with the nitrogen of the isocyanate group and that the coordination of the catalyst with the substituent may also occur. These expectations were confirmed by the infrared technique and the copolymer structure. ZUSAMMENFASSUNG:Die Copolymerisation verschiedener Monoisocyanate rnit Athylenoxid wurde im Zusammenhang mit der alternierenden Copolymerisation von Phenylisocyanat mit Athylenoxid durch Triathylaluminium als Katalysator untersucht. Es wurde gefunden, dal3 aliphatische und alicyclische Isocyanate nicht copolymerisierbar sind, viele der aromatischen Isocyanate jedoch Copolymere geben; es wird vermutet, dal3 es sich um alternierende Copolymere handelt. Bei den substituierten Phenylisocyanaten wurde gezeigt, dal3 die orthosubstituierten Isocyanate Copolymere in hoher Ausbeute ergeben, ausgenommen ist nur das o-Anisylisocyanat. Es besteht keine Beziehung zwischen der Ausbeute des Copolymeren und den HAMMETTschen Substituenten-Konstanten. Diese Ergebnisse lassen vermuten, dal3 sich das Triathylaluminium vorzugsweise mit dem Sauerstoffatom und nicht mit dem Stickstoff der Isocyanatgruppe koordiniert und dal3 sich die Koordination des Katalysators mit dem Substituenten in gleicher Weise vollzieht. Diese Vermutungen wurden durch die Ergebnisse der Infrarotspektroskopie und die Struktur des Copolymeren gestutzt.

Quasi-Living Copolymerization of Aryl Isocyanates and Epoxides

“…In general, this strategy can afford efficient copolymerization to form a novel class of PUs possessing a primary alternating microstructure with a narrow molecular weight distribution, as demonstrated in Scheme and testified by 13 C NMR and gel-permeation chromatography (GPC) in Figure . In contrast to previous work, − the resonances at 154.74–155.93 ppm and absence of signals at 163 ppm in the 13 C NMR spectra (Figures a and S4) indicate the formation of a urethane unit instead of an acetalic structure, strongly suggesting the regioselective attack of CN bond in MPI by the oxyanion. The resonances located at 152.44–153.35, 69.03–72.97, and 78.65–80.73 ppm indicate the existence of minor moieties constructed from consecutive MPI or BO units.…”

“…PU is an important class of polymer applied widely in thermoplastics, foams, adhesives, and so on, − which is traditionally obtained by polyaddition of dihydric alcohol with diisocyanate, as shown in Scheme . About half a century ago, another strategy by ring-opening alternating copolymerization of monoisocyanates and epoxides was first reported. − Unfortunately, a mixture of polyether and copolymer composed of primary acetalic units was obtained, the structure was poorly defined, and the mechanism was ambiguous at that time. Thereafter, controlled copolymerization of monoisocyanates and epoxides remains a great challenge and has aroused renewed interest very recently, in which a diamagnesium catalyst was utilized.…”

Addition Polymers of Monofunctional Isocyanates

“…The ^C=N-group, such as in ketimines R 2 • C=NH or in guanidine derivatives (RHN) 2 • C=NH, absorbs in the region of 5.95-6.25 fim, which is rather close to the carbonyl band [18]. This is borne out by the work of Furukawa et al [19,20] who have prepared the alternating copolymers of aromatic isocyanates and ethylene oxide. Chemical degradation gave proof of acetalic structures such as -t-CH 2 CH 2 O-C-N-Ph III which is analogous to II for the homopolymer.…”

Heterocycle/Heteroallene Ring‐Opening Copolymerization: Selective Catalysis Delivering Alternating Copolymers

“…Early studies demonstrated that slow alternating ArNCO/ EO ROCOP was possible when employing aAlEt 3 /H 2 O(2:1) catalyst system (TOF 0.3 h À1 ,2 58 8Cf or PhNCO). [215,216] The addition of the isocyanate to the epoxide occurred with retention of the C = Nb ond to form an acetal linkage or with retention of the C=Ob ond to form au rethane linkage (Figure 34);t he semi-crystalline polymer contained two thirds acetal linkages (M n = 1-2.1 kg mol À1 , T m = 80-83 8 8C).…”