Polydiacetylenes solubility

The nonlinear optical properties of novel, soluble polydiacetylenes are reviewed and discussed. 

Recently, polydiacetylenes have been discovered which are soluble in common organic solvents (12). These polymers have urethane substituent groups of the form... 

The influence of the side-groups will be much less in solution but, until recently, there have bean few studies of polydiacetylene solutions since most fully polymerized materials are insoluble. However, a number of soluble polydiacetylenes have now been identified (, 57, 59, ). In the case of... 

Since Patel discovered in 1978 that poly3BCMU (R = R = —(CH2)3—OCONH— CH2—COO—(CH2)3CH3, cf. Table 1) is a readily soluble polymer the study of the solution properties of polydiacetylenes attracted increasing interest 66.i< -u5) with such samples the molecular weight and its distribution can be determined using standard techniques and related to the conversion and other experimental parameters. This analysis has been carried out in great detail for PTS-12... 

Many aspects of the preparation and properties of polydiacetylenes are the subject of lively debate. This review presents recent results that bear on some of these controversies. First the relationship of diacetylene monomer crystal structure and solid-state reactivity is discussed. Secondly the temporal evolution of solvato-chromio transitions of soluble polydiacetylenes is displayed. Optical and Raman spectra reveal the occurrence of an intermediate form of the polymer. A model compatible with these results is described. 

Probably themostpromisingpolymers were the various polydiacetylenes, hereafter denoted PDA, that not only shows a yellow-to-blue or yellow-to-red transition but in many cases have a very large statistical length. Here again, to achieve the solubility of PDA in a common organic solvent, a very large substituent is added. 

Alloisio. M. Moggio, I. Comoretto, D. Cnniberti, C. DelTErba. C. Dellepiane, G. Soluble polydiacetylenes Molecular properties and solid state organisation. Synth. Met. 2001. 124. 253-255. 

These polydiacetylenes are soluble in common organic solvents, such as CHCI3, due to the high entropy content of the complicated urethane substituent groups. The discovery of these soluble polymers has lead to a number of interesting developments the first determination of the chain length in a polydiacetylene, [about 1000 repeat units for both polymers(2)], characterization of the chain dynamics for polydiacetylenes in solutlon(3), discovery of the remarkably strong two photon absorption now known to be characteristic of the polydiacetylene backbone(4), and discovery of a conformational transition in the polymer solutions, referred to as a "visual conformational transi-tlon"(1). 

Additional soluble polydiacetylenes have been discovered which show temperature- or solvent-induced color changes with absorption shifts similar to poly4BCMU(6-8). These solutions are believed to... 

Previous characterization studies gave information on both L and the degree of polydispersity for the soluble polydiacetylenes with BCMU side groups. For poly-4BCMU, L 2400... 

Since polydiacetylene 4BCMU has a rodlike conformation with a large axial ratio (length/diameter) in certain solvents, it is a likely candidate for a lyotropic polymer. However, it has low solubility in those solvents and no liquid crystalline phase has been observed. As described above, a rod-to-coil conformational transition can be induced in the PDA 4BCMU by changing the solvent... 

In contrast to the polydiacetylenes, thin films of polysilane polymers are more readily formed, and are transparent tiuoughout the visible spectrum. These polymers have a long catenated o-bonded silicon backbone with two sidegroups, usually carbon based, attached to each Si atom in the backbone chain [7]. They are soluble in most hydrocarbon solvents and thin films of excellent optical quality can be fabricated with conventional spinning and... 

Polydiacetylenes with different symmetrically substituted side groups differ mainly in terms of crystal quality, stability, and solubility the influence on the third order susceptibility is rather small [118]. Interesting effects where found, however, in the imsymmetri-cally substituted diacetylene NP/4-MPU. This diacetylene forms a non-centrosymetric crystal with a significant [124, 125]. The second harmonic generation with this crystal can... 

A. D. Nava, M. Thakur, and A. E, Tonelli, CNMR structural studies of a soluble polydiacetylene po-ly(4BCMU), Mocromolecules 2i.3055 (1990). 

Recently, a soluble unsymmetrically substituted polydiacetylene (Fig. 26.2) has been reported to exhibit an SHG signal from spin-coated or cast films without recourse to poling [33,34] (see next paragraph for the definition of poling). The polymer film showed apprecia-... 

Disordered samples of polydiacetylenes can be prepared by a number of routes. First, the less perfectly polymerizing crystals can be obtained in a fibrilar form due to disruption of the crystal lattice by internal strain, e,g, (120). Secondly, similar samples can be obtained by the removel of unreacted monomer from partially polymerized crystals. Thirdly, single crystals can be deformed mechanically. Fourthly precipitates in the form of films or powders can be obtained for soluble diacetylenes and finally the solutions of such soluble materials can be studied directly. 

Although most of these polymers are insoluble, several soluble polydiacetylenes have been synthesized. The most studied are those containing... 

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