Detection and identification of VOCs in their vapor phase is essential for safety and quality assessment. In this work, a novel platform of a paper-based polydiacetylene (PDA) colorimetric sensor array is prepared from eight diacetylene monomers, six of which are amphiphilic and the other two are bolaamphiphilic. To fabricate the sensors, monomers are coated onto a filter paper surface using the drop-casting technique and converted to PDAs by UV irradiation. The PDA sensors show solvent induced irreversible color transition upon exposure to VOC vapors. When combined into a sensing array, the color change pattern as measured by RGB values and statistically analyzed by principal component analysis (PCA) is capable of distinguishing 18 distinct VOCs in the vapor phase. The PCA score and loading plots also allow the reduction of the sensing elements in the array from eight to three PDAs that are capable of classifying 18 VOCs. Utilizing an array containing only two PDAs, various types of automotive fuels including gasoline, gasohol and diesel are successfully classified.

Mono-and diamides derivatives of 10,12-pentacosadiynoic acid (PCDA) were synthesized from condensation of PCDA with various aliphatic and aromatic diamines. Polydiacetylenes of the amido-PCDA derivatives were prepared by photopolymerization of their molecular assembly homogeneously dispersed in aqueous media. Thermochromic properties of the resulting polydiacetylene sol were studied by temperature variable UV-vis spectrometry along with photographic recording. The color transition temperatures and thermochromic reversibility of the polymers are varied depended on the number of amide groups and the structure of the aliphatic and aromatic linkers. The phenylenediamide and polymethylenediamide PCDA derivatives give polydiacetylenes with complete thermochromic reversibility, while the polydiacetylenes obtained from 1,2-cyclohexylene and glycolic chain diamide derivatives exhibited irreversible thermochromism, whereas the polymers attained from the aromatic monoamide analogues are partially reversible. The variation of the linkers also allows the color transition temperature of the polydiacetylene to be tuned in the range of 20 °C to over 90 °C. The results provide a fundamental idea about the factors affecting the thermochromic properties of polydiacetylenes toward the development of materials for universal thermal indicators.

A series of bisdiynamide lipids containing various lengths of methylene spacer (m = 2, 3 and 4) between the diynes and the diamide headgroup and number of methylene units (n = 6 and 9) in their hydrophobic tails are synthesized. All six lipids synthesized can be dispersed in water and photopolymerized by UV irradiation to give the corresponding polydiacetylene (PDA) sols. The color transitions from blue to red during heating-cooling cycles of the PDA sols are photographically recorded and monitored by UV-vis absorption spectroscopy. The bisdiynamide PDAs exhibit excellent thermochromic reversibility and the color transition temperature can be tuned between ca. 25-55 °C by the variation of m and n values. Temperature indicators can be obtained by applying a screen printing ink formulated from the bisdiynamide monomer on plastic substrates followed by UV irradiation to generate desired patterns of thermochromically reversible PDAs.