We report the effect of phenol on the phase behaviour and physical properties of polydiacetylene gels. Specifically, they are o-dichlorobenzene (o-DCB) solution of poly[4,6-decadiyne-l,10-diol-bis(nbutoxycarbonylmethylurethane)], abbreviated as P(3BCMU), and toluene (Tol) solution of poly[5,7- dodecadiyne-l,12-diol-bis(n-butoxycarbonylmethylurethane)], abbreviated as P(4BCMU). The polymer concentration was 0.1 to 2 wt%, and the molar ratio z of phenol to the monomer unit of the polydiacetylenes was regulated within 20. The gel-to-sol transition temperatures T t were determined by measurements of shear modulus for the P(3BCMU)/o-DCB system and by a falling ball method for the P(4BCMU)/Tol systems. Tt decreased with increasing z and the systems with polymer concentration of 1 wt% turned into a sol at room temperature in the range of z > 10. The temperature dependence of alternating-current (a.c.) conductivity a,c at 1 kHz exhibited a maximum at a temperature ca. 20 K below the transition temperature. The value of ~rac decreased steeply at the electrical transition temperature T~, which also decreased with increasing z. Ultra-violet and visible-light spectra for the P(3BCMU)/o-DCB and P(4BCMU)/Tol systems shifted to the short-wavelength side with increasing z. The infra-red spectra indicate that the intramolecular hydrogen bonds between the N H and C=O groups of the side groups are cleaved by phenol. These results indicate that the conjugated rod-like conformation is made unstable by phenol. To clarify the mechanism of crosslinks of the gel network, the crystallinity of concentrated P(3BCMU) gels was determined by wide-angle X-ray diffraction. No crystallinity was observed in the gels of C less than 30 wt%.
Посилання на статтю:
Effect of scission of hydrogen bonds by phenol on phase behaviour and physical properties of polydiacetylene gels: P(3BCMU) and P(4BCMU) / Pingfan Chen*, Keiichiro Adachi~ and Tadao Kotaka // Polymer. – 1993. – Vol 34. – P. 4953-4960.