Chromatic Studies of a Polymerizable Diacetylene Hydrogen Bonding Self-Assembly:  A “Self-Folding” Process To Explain the Chromatic Changes of Polydiacetylenes

• Published in: Langmuir Vol. 15; no. 11; pp. 3972 - 3980
• Main Authors: Huo, Qun, Russell, K. C, Leblanc, Roger M
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 25.05.1999
• Subjects: Applied sciences; Exact sciences and technology; Physicochemistry of polymers; Polymerization; Polymers and radiations; Self assembly; Monolayer; Compressibility; Bifunctional compound; Polyunsaturated fatty acid; Diacetylene polymer; Air water interface; Triazine derivative polymer; Experimental study; Amphiphilic compound; Mechanism; Thermochromism; Mixed monolayer; Conjugated polymer; Amine polymer; Polyynic compound; Photopolymerization; Optical properties; Triazine derivatives; Polyacid; Property structure relationship; Solid polymerization; Monomer; Hydrogen bond
• ISSN: 0743-7463; 1520-5827
• DOI: 10.1021/la990025f

In the present study, a new diacetylene compound (PDATAZ), which readily forms a complementary hydrogen bonding self-assembly at the air−water interface or in the solid state with barbituric acid (BA) or cyanuric acid (CA), was designed and synthesized. The photopolymerization studies of PDATAZ and its assembly with BA or CA have revealed some important insights on the chromatic properties of polydiacetylenes. It was found that the chromatic property of polydiacetylenes is determined by whether the polymer chain is capable of adopting a linear chainlike shape. With the continuous increase of the length of the polymer chain, the original linear polyenyne backbone starts to “self-fold” to a “zigzag” structure due to the free rotation of single bonds within the polymer chain. The efficient π-electron delocalization along the polyenyne backbone is interrupted by this process, leading to a chromatic change from the blue to red form of polydiacetylenes. If there are strong intermolecular interactions existing between the polar groups of the side chains, such as the complementary hydrogen bonding network between the triaminotriazine (TAZ) moiety of the diacetylene amphiphile and its complementary components, the movement of the side chains is restricted and the folding process of the polymer backbone is inhibited. The polymer backbone is able to maintain its extended chainlike conformation, leading to only the blue form absorption band.