Synthesis Polydiacetylenes

ideal spatial parameters topochemical polymerization

synthesis of polydiacetylenes occurs through topochemical polymerization of 1,3-diynes. typically, must occur in solid state because many diynes undergo both 1,2 , 1,4 polymerization in solution – such case diiodobutadiyne, , other diynes electron withdrawing substituents. ideal arrangement of diynes in solid state repeat distance of 5Å, 45° tilt angle, , 3.5Å distance between c1 of 1 monomer , c4 of adjacent diyne monomer.

usually, polymerization accompanied color change due presence of extended π-system. in addition, many pdas exhibit thermochromism caused twisting of polymer backbone, changing amount of conjugation in system. depending upon structure of monomer, resulting pda can have interesting properties such formation of vesicle or tube structure.

the chromatic transition blue red phase of pda caused electronic structure of pdas backbone featured alternative carbon double bond , carbon triple bond. upon exposure external stimuli such thermal, chemical , mechanical stimulus, conjugation effect endow chromatic properties type material. far pure or intrinsic pdas concerned, blue red phase transition irreversible, if head groups of pdas side chain strengthened other structure, example chelation metal oxide nanoparticles, provide resilience of backbone conduct reversible color change. several recent researches assisted dft simulation have shown chromatic properties modified adjusting side chain structures of pda. development thin film fabrication technology such inkjet printing, pdas coated on different substrate materials multifunctional sensor, example kapton films, aluminum foil or conventional paper.