Preparation and photocrosslinking behaviors of polyesters derived from trans‐2,2′‐dihydroxystilbene

Abstract

SYNOPSISThe monomer, truns-2,2'-dihydroxystilbene (DHS), has been prepared by asymmetric photocleavage (254 nm) of coumarin dimer acid derived from coumarin dimer. Four new polyesters are successfully synthesized by interfacial polycondensation of the DHS with adipoyl chloride, azelaoyl chloride, sebacoyl chloride, and dodecanedioyl dichloride, respectively. The reduced viscosities of the polyesters decrease from 0.32 to 0.11 dL/g as the number of methylene unit in diacid chlorides increases from 4 to 10. From DSC investigation, it is found that the polyesters are semi-crystalline polymers with T,,, = 39-192°C. Under 350 nm light, photocrosslinking behavior in solution and film-state is investigated by UV spectral change with irradiation time (350 nm). The photoreactive stilbene chromophores in the main chain dimerize to form cyclobutane derivatives, and lead to crosslinking of the polyesters. Photosensitivity in the film state has also been evaluated by their characteristic curves. Polyester from dodecanedioyl dichloride (5d) exhibits the highest initial reaction rate and ultimate crosslinking ratio. 0 1995 John Wiley & Sons, Inc.

Liquid crystalline and photoactive poly[4,4′-stilbeneoxy]alkylbiphenylphosphates

“…Flexibility of photocrosslinkable main chain liquid crystalline polymers was improved by introducing flexible spacer, consisting of polymethylene chains in between the mesogenic units [6]. Semi-crystalline polyesters were synthesized from trans-2,2 0 -dihydroxystilbene with aliphatic diacid chlorides for the synthesis of photoresists [7]. Photo-crosslinkable liquid crystalline polymers of trans-4,4 0 -dihydroxystilbene with azobenzene were synthesized and reported that the polymer exhibited photo-crosslinking [8] and fluorescence [9] properties.…”

Studies on photocrosslinkable‐cum‐flame retardant poly(benzylidene phosphoramide ester)s

“…The methylene protons of cyclopentanone appear at 2.7 ␦, whereas the same protons of the cyclohexanone and cycloheptanone containing polymers appear around 2.7-2.9 ␦ and 1.7-1.8 ␦, respectively. 32 The proton-decoupled 13 C-NMR spectra of the polymers Ie and IIa are shown in Figure 1. The chemical shift assignments were carried out using the normal additivity parameter of the substituents in the benzene ring and the considerations of the off-resonance spectra in conjunction with the difference in intensities among the quaternary methine, methylene, and methyl carbons.…”

“…11,12 Semicrystalline polyesters were synthesized from trans-2,2Ј-dihydroxystilbene with aliphatic diacid chlorides for the preparation of photoresists. 13 Photosensitive polyarylates are used as photoresist and nonlinear optical materials. 14 Poly[bis(benzylidene ester)]s have been synthesized and studied for their liquid crystalline and photochemical properties.…”

Studies on photocrosslinkable-cum-flame retardant poly(benzylidene phosphoramide ester)s

“…The methylene protons of cyclopentanone appear at 2.7 ␦, whereas the same protons of the cyclohexanone and cycloheptanone containing polymers appear around 2.7-2.9 ␦ and 1.7-1.8 ␦, respectively. 32 The proton-decoupled 13 C-NMR spectra of the polymers Ie and IIa are shown in Figure 1. The chemical shift assignments were carried out using the normal additivity parameter of the substituents in the benzene ring and the considerations of the off-resonance spectra in conjunction with the difference in intensities among the quaternary methine, methylene, and methyl carbons.…”

“…11,12 Semicrystalline polyesters were synthesized from trans-2,2Ј-dihydroxystilbene with aliphatic diacid chlorides for the preparation of photoresists. 13 Photosensitive polyarylates are used as photoresist and nonlinear optical materials.…”