Solutions of polydiacetylenes in good and poor solvents : a light and neutron scattering study

Abstract

To cite this version:M. Rawiso, J.P. Aime, J.L. Fave moléculaire élevée. On n'a pas observé de véritables solutions rouges de bâtonnets isolés, même à des concentrations aussi faibles que 0,5 x 10-3 g 1-1 de P-4BCMU de grande masse moléculaire (Mw = 1,67 x 106 gmole-1) ou 0,5 gl-1 de P-4BCMU de petite masse moléculaire (Mw = 4,32 x 104 g mole-1). Ceci suggère que dans toutes les expériences sur les solutions bleues ou rouges de P-3BCMU et P-4BCMU on n'observe que des agrégats. Cependant, la question reste ouverte de savoir si les modifications de la structure électronique observées sont dues à une agrégation et/ou une cristallisation partielle, ou si elles proviennent d'une transition pelote-bâtonnet suivie d'une agrégation subséquente des bâtonnets. Finalement, on discute le processus d'agrégation tel qu'il est observé par diffusion des neutrons aux petits angles. Abstract. 2014 The properties of the P-3BCMU and P-4BCMU solutions in good and poor solvents have been investigated, by use of light and neutron scattering techniques. In good solvents, P-3BCMU and P-4BCMU dissolve with a yellow color and form semi-rigid coils in a trans isomeric state. Their internal structure is better described by a continuous model of a wormlike ribbon than by a model of discrete defects separating misoriented rigid platelets of variable lengths. At room temperature and for both polydiacetylenes, the longitudinal persistence length is found to be close to 160 Å and the mean square radial radius of gyration, which is related to the side extension of the macromolecules, is of the order of 60 Å2. The conjugated chain stiffness does not seem to depend on the presence or absence of Hydrogen bonds between neighboring side groups, as long as a small enough proportion of such bonds are formed. In poor solvents, specifically for red solutions of P-4BCMU in toluene, the chains form complex aggregated structures of large molecular weight.No evidence for red solutions of isolated rod molecule has been found, even for concentrations as low as 0.5 x 10-3 g 1-1 with high molecular weight P-4BCMU (Mw =1.67 x 106 g mole-1) or 0.5 gl-1 with low molecular weight P-4BCMU (Mw ~ 4.32 x 104 g mole-1). This strongly suggests that all experimental J. Phys. France 49 (1988) Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphys:01988004905086100 862 investigations on the blue and red solutions of P-3BCMU and P-4BCMU observe the aggregated structures only. However, it still remains an open question whether the observed change in the electronic structure is caused by aggregation and/or partial crystallization or whether the color change originates from an instantaneous coil to rod transition followed by subsequent aggregation of the rods. The aggregation process, as seen by small angle neutron scattering, is studied and discussed.

Dissolution and Spectroscopic Properties of the Polydiacetylene Poly(10,12-docosadiyne-1,12-diol-bisethylurethane)

“…[16,29,42] Neutron scattering studies have shown that in solution the yellow, disordered, polymer is best described as a worm-like chain. [43] The optical and Raman spectra of the blue-phase polymer are similar to those of the as polymerised, crystalline polymer, hence, it follows that the polymer structure is also similar in both situations. [16,42,44,45] The transition between disordered and ordered forms has been considered to be due to either the full extension of individual polymer chains or extension associated with self-collapse of individual polymer chains and aggregation.…”

“…Tetrahydrofuran and DMF are good solvents for the nBCMUs. [43,53] Tetrahydrofuran has a similar boiling point to chloroform and, therefore, was not investigated as a solvent for 9EU. In the initial study, DMF was not heated close to its boiling point.…”

“…450 nm typical of disordered, worm-like polydiacetylene chains. [43] In addition there is a more structured absorption at longer wavelengths indicating the presence of ordered polymer. In second derivative plots the latter gives rise to a principal minimum at 610 nm (16 400 cm -1 ) and weaker minima at ca.…”

Optical and Electrochemical Transducers Based on Functionalized Conjugated Polymers

“…This intriguing effect has been extensively studied and has led to the development of various thermochromic polythiophene [4,5,[12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29], polysilane [30][31][32][33][34][35][36][37][38][39][40][41], and polydiacetylene [42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57] derivatives (Figure 2.1). As an example of thermochromism reported for some neutral conjugated polymers, Figure 2.2 shows the temperature-dependent UV-vis spectrum of sodium poly[2-(4-methyl-3-thienyloxy)ethanesulfonate] in...…”

Electrochromic carbon nanotube polydiacetylene and zinc oxide hybrids

“…In order to obtain absolute measurements, SANS experiments were carried out by Wegner et al [24]. P3BCMU and P4BCMU samples with comparatively low MW (~43200) and reasonable polydispersity were used in the study.…”