Polydiacetylenes PDAs

Although the production of polymeric material had been thought, since the 1950s, to occur in the preparation of certain diacetylene materials. 

Variation of the side-groups determines the morphology of PDAs, with coffin-shaped crystals (PTS) and fibres (DCH) as the two extreme crystal forms. More complex side-groups can also give PDAs that can form LB films or be cast as amorphous films. 

Attempts to calculate the PDAs have been made [104-106], but since there is no agreement between workers, there remains a need for further theoretical study to match the mounting degree of experimental data. 

Early THG measurements on single-crystal PDAs (PTS and DCH [107]) showed large values of x (10 °esu at. 9 /am) and a large anisotropy between the different chain orientations. Recently, more thorough time-resolved and dispersive measurements have been made on thin film 

The use of soluble PDAs in device-like structures is possible because they can be cast to form waveguides or quasi-waveguides. The films have various degrees of order, and this is manifested as a difference in colour the red phase is less ordered than the blue phase. The time-resolved intensity-dependent refractive index n2 for 4-BCMU has been measured by plasmon techniques [110] and found it to be 10 m W Measurement of interferometric bistability in the same compound [110] has given an appreciably higher figure (5 X 10 m W at 653 and 700 nm). The reason for this discrepancy is not clear, and more work is needed in this area. THG studies on other soluble PDAs also give values around 10 esu, which corresponds to = 10 m [111]. 

---

In addition to simple ions, CPs can be used to detect larger, potentially bio-active materials. An early example of such a system employed the polymer polydiacetylene (PDA) (Fig. 6) for viral detection [14],... 

Jung YK, Park HG, Kim JM. Polydiacetylene (PDA)-based colorimetric detection of biotin-streptavidin interactions. Biosens Bioelectron 2006 21 1536-1544. 

Lee NY, Jung YK, Park HG. On-chip colorimetric biosensor based on polydiacetylene (PDA) embedded in photopolymerized poly(ethylene glycol) diacrylate (PEG-DA) hydrogel. 

In this paper we report functional waveguides exhibiting SHG in tapered thickness 2-methy1-4-nitroani1ine(MNA) thin film crystal waveguide, and all optical bistabi1ity,in tensity dependent optical modulation in vacuum evaporated polydiacetylene(PDA) thin film waveguides. 

All Optical Bistability of Vacuum Evaporated Polydiacetylene (PDA.12-8) Film Waveguide with a Grating Coupler... 

The synthesis and characterization of polyacetylene (PA) provided new incentive for understanding 7r-electronic spectra, electron-phonon interactions and electronic correlations[l, 2, 14]. The electrical conductivity of chemically doped PA rivals that of metals. Families in Fig. 2 such as polydiacetylenes (PDAs), poly thiophenes (PTs), cr-conjugated polysilane (PSs) and polyparaphenylene vinylene (PPVs), among... 

The discussion above left aside an entire class of CPs, the polydiacetylenes (PDAs) (see Table 1). Their study has followed a path similar to that of other CPs, but with only occasional intersections. Indeed, they differ greatly from other CPs in many respects. PDAs have a feature that is almost unique in the entire polymer field, and not only among CPs single crystals of macroscopic size can be obtained. They owe that to their peculiar polymerization mechanism, which is a topotactic reaction occurring in the mon-... 

Poly diacetylenes. The polydiacetylenes (PDA s) are unique among highly conducting polymers discovered in the past years in that they can be obtained as highly perfect macroscopic single crystals.68 Upon solid-state polymerization of... 

Figure 6 Segment of a typical polydiacetylene PDA) backbone. The side chain groups are substituted by hydrogen atoms and the translationally invariant unit cell is surrounded by broken lines. The carbon-carbon bond distances vary for different models as defined in Table 4...

Polydiacetylenes (PDAs) were the first class of conjugated polymer that could be produced in pure, single crystal form by the polymerization of the corresponding crystals of the monomeric dialkyne derivatives. DC measurements had demonstrated large electron mobilities in such PDA crystals. Because of this they were considered at the time to be of potential application as an organic semiconductor layer in electronic devices. While these hopes were unfulfilled, these... 

Similar properties were observed only in single polydiacetylene (PDA) quantum wires, embedded in their monomer crystal. Such a conjugated system has exhibited an almost undetectable spectral diffusion and blink-... 

Topochemical reactivity and solid-state polymerization strongly merged in the extensive studies of diacetylene (1) polymerization by G. Wegner and collaborators beginning in 1969. There are two recent books devoted to polydiacetylenes (PDA, 2) (9,10), and it is fair to say that the literature of fully ordered macromolecules would be much less voluminous without the extensive research associated with diacetylene polymerization and the chemical, structural, and physical properties of these polymers. 

Studied the effects of bond and atom alternations and of chain pairing on the NLO properties of one-dimensional periodic semiconductors, with special emphasis on polydiacetylenes (PDA). The properties were referred to as and but we prefer and this is more correct to write 3(A)/A and y(N)/N with N, the number of units, tending toward infinity. Another Hiickel investigation [174] concentrated on (a) the second-order NLO responses of asymmetric unit cell polymers that modeled polymethineimine (PMI) and (b) the relations between bond alternation, atom alternation, and the sign and magnitude of p(/V)//V. At this level of theory the equations reduced to the non-self-consistent scheme detailed above and can be called uncoupled. 

Light and neutron small-angle scattering (SANS) has been performed on different polydiacetylenes (PDA) in... 

Jung, K., Kim, T.W., Park, H.G., and Sob, H.T. 2010. Specific clorimetric detection of proteins using bidentate aptamer-conjugated polydiacetylene (PDA) liposomes. Adv. Funct. Mater. 20 3092-3097. 

It must be noted that the values reported in the literature vary over broad ranges. Therefore, the values listed here reflect only the general behavior of several classes of compounds. It can be seen in Table 3.5 that trans-polyacetylenes (PAs) and polydiacetylenes (PDAs) exhibit the largest third-order NLO susceptibilities. The x value of cis-PA (not shown) is more than an order of magnitude smaller than that of trans-PA. Derivatives of poly-p-phenylene, poly(phenyl-ene vinylene), and polythiophene also exhibit NLO activity, but to a much lesser extent than PAs and PDAs. As pointed out above, polysilanes also possess quite large x values. This is explained by the cr-conjugation of the silicon chain, which implies a pronounced delocalization of cr-electrons. A very large x value... 

---