ISSN:
0360-6376
Keywords:
Physics
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The polyamides were prepared from the dicarbonyl chloride of (+) (S)- or (-)(R)-trans-1,2-cyclopropanedicarboxylic acid (C3A) with either the dihydrochloride salt of (+)(S)- or (-)(R)-trans-1,2-diaminocyclopropane (C3B) or the dihydrobromide salt of (+)(S)- or (-)(R)-trans-1,2-bis(methylamino)cyclopropane (C3MB) by interfacial polycondensation. Several diamide model compounds composed of these monomers were also synthesized. The polyamides [poly(C3A-C3B)] derived from C3A and C3B have the capability of hydrogen bonding, while the polyamides [poly-(C3A-C3MB)] derived from C3A and C3MB do not. Poly(C3A-C3B) were insoluble in common organic solvents except strong acids. Poly(C3A-C3MB) were soluble in common organic solvents. Poly(C3A-C3B) had melting points higher than 300°C. Poly(C3A-C3MB) melted at 180-235°C. The ORD and CD study has shown that poly(+)C3A(+)C3B in methane sulfonic acid (MSA), 2,2,2-trifluoroethanol (TFE) (5 v % MSA), and tetramethylenesulfone (TMS) (5 v % MSA) exhibits a very strong Cotton effect or CD peak at 212-218 mμ, attributable to a component of the split π-π* transition of the amide chromophores. Poly(+)C3A(+)C3MB in MSA and TFE (5 v % MSA) shows a strong Cotton effect or CD peak at 217-223 mμ and an intermediate Cotton effect or CD trough at 202-204 mμ as well as an intermediate Cotton effect or CD trough at 220-222 mμ and an intermediate Cotton effect or CD peak at 202-204 mμ in TFE and TMS. These peaks and troughs may be assigned to splitting of the π-π* transition. The CD spectra of poly(+)C3A(+)C3MB in nonacidic media are quite different from those in acidic media: they are almost mirror images. The CD spectra in this transition induced by MSA suggests that a transition from a compact helix to another more extended helix with opposite handedness occurs similar to poly-L-proline I ⇄ II. This transition may be explained by electrostatic repulsion between protonated amide groups. Viscosity data have shown that the conformation is changed to a highly extended from in acidic media. The polyamides and diamides derived from enantiomers exhibit mirror image spectra. Poly(+)C3A(+)C3B and poly(+)C3A(+)C3MB in every solvent studied exhibit a marked enhancement of the rotatory strength of ORD and CD with respect to the corresponding diamide models.
Additional Material:
12 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pol.1981.170190210
