Haloaldehyde polymers, 18. Rate of copolymerization of chloral with isocyanates

Abstract

Cryotachensic copolymerization of chloral with various aliphatic and aromatic isocyanates, initiated by lithium tert-butoxide and triphenylphosphine at O"C, was followed by 'H NMR spectroscopy. Information on the mobility of comonomers and solvent molecules in the polymerization mixture was obtained by measuring the line width of the signals. Relative rates of incorporation of chloral and isocyanates into the copolymer were determined, indicating that the copolymer was not uniform in structure and that the content of isocyanate units increased significantly in the final stages of copolymerization.

Haloaldehyde Polymers LXII. High Resolution Solid State 13C NMR Spectra of Chloral and Bromal Polymers

“…The observation that the acetal carbon resonance was not altered by the presence of p-chlorophenyl isocyanate units indicates that the structure of chloral units in the copolymer is similar to that in the homopolymer. This is consistent with the previously discussed structure 25 of segregated p-chlorophenyl isocyanate units in the polymer chain.…”

Haloacetaldehyde polymers and macromolecular asymmetry

“…A block copolymer was produced. 40 It consisted of the initial chloral homopolymer block followed by a short intermediate composition but ultimately followed by a terminal alternating chloral/ isocyanate block. When a hindered aliphatic isocyanate such as isopropylisocyanate was used as the comonomer, the isocyanato growing end cannot propagate.…”