Conversion of the polydiacetylene of bis(ethylurethane) of 5,7‐dodecadiyne‐1,12‐diol to a non‐thermochromic crystalline form by solvent extraction

Abstract

Exposure of crystals of the thermochromic polydiacetylene (PDA) of the bis(ethy1urethane) of 5,7-dodecadiyne-l, 12-diol (ETCD) to the hot solvents chlorobenzene and Nfl-dimethylformamide results in the conversion of the material to a nonthermochromic form. The material resulting from chlorobenzene extraction retains its original shape and is crystalline. It was further characterized by differential scanning calorimetry, X-ray powder diffraction, and Raman spectroscopy. Significant amounts of chlorobenzene are not retained in the extracted material. It is indicated that chlorobenzene extracts monomer and oligomer causing expansion of the lattice, some disordering of the polymer chains, and removal of the interactions which allow observation of thermochromism. The implications of these findings for the role of possible mechanical strains in the crystal structure-thermochromism relationship in urethane-substituted PDA crystals are discussed.0 1993, Hiithig & Wepf Verlag, Base1CCC 0025-1 16X/93/$05.00

Structural Aspects of the Thermochromic Transition in Urethane-Substituted Polydiacetylenes

“…Thermochromic vs Nonthermochromic Poly-(ETCD). Solvent extraction of poly(ETCD)-P with boil- ing chlorobenzene 21,22 removes oligomer as well as residual monomers and produces a red nonthermochromic form of PDA, poly(ETCD)-CE, while giving orange extracts (16.0 wt % weight loss). Unit cell expansion was observed by X-ray powder diffraction (Table 3) for poly-(ETCD) after chlorobenzene extraction.…”

“…The four methylene units between backbone and urethane function in the side group are found to exhibit a change in the conformer population in the course of the transition as evidenced by infrared and solid-state 13 C NMR spectroscopy. , The ambiguity that residual monomer contributes to the phase transition was ruled out by study on poly(IPUDO), which has a conversion from monomer to polymer greater than 99% . In an attempt to find the nature of the thermochromic phase transition, a crystalline nonthermochromic form of poly(ETCD) was prepared from its thermochromic form. , Interestingly, the nonthermochromic form of poly(ETCD) does not lose crystallinity and maintains vibronic structure in the reflection spectra polarized parallel to the chain axis . Nonetheless, no attempt has been made to establish a correlation between thermochromic and nonthermochromic poly(ETCD) in conjunction with their structures.…”

“…20 In an attempt to find the nature of the thermochromic phase transition, a crystalline nonthermochromic form of poly-(ETCD) was prepared from its thermochromic form. 21,22 Interestingly, the nonthermochromic form of poly-(ETCD) does not lose crystallinity and maintains vibronic structure in the reflection spectra polarized parallel to the chain axis. 22 Nonetheless, no attempt has been made to establish a correlation between thermochromic and nonthermochromic poly(ETCD) in conjunction with their structures.…”

Dose Dependence of the Charge Carrier Mobility and Decay Kinetics in Radiation Polymerized Diacetylenes

“…These fits yielded a value close to 1 cm 2 V -1 s -1 for the product X max ∑μ(0) for both ETCD and IPUDO. It has been reported by Sandman et al that the maximum monomer conversion in both ETCD and IPUDO single crystals is close to 1. Using this value of X max results in a charge carrier mobility for both compounds close to 1 cm 2 V -1 s -1 .…”