The solid state photobleaching and photocrosslinking of copolymers containing the anthracene chromophore

Abstract

SynopsisCopolymers of methyl methacrylate with an anthracene derivative are photodegraded in the solid state to give crosslinked material. The mechanism of insolubilization is dependent on the nature of the substituents at both the 9 and 10 positions of the anthracene chromophore. Photodimerization is the primary and most efficient cause of insolubilization if one of these positions is unsubstituted. Photodimerization does not occur if both of these positions are substituted; instead crosslinking is caused by photolysis of the endoperoxide of the parent anthracene. Bromination can sensitize the initial photooxidation and subsequent crosslinking in a copolymer where photodimerimtion does not occur. As a consequence of the crosslinking the rate of photobleaching of the anthracene chromophore by 'Ago2 is severly curtailed. Poly(methy1 methacrylate), a positive-tone polymer when exposed to UV light, is made negative acting by the incorporation of bound anthracene chromophores. EXPERIMENTAL Synthesis of Materials(1 0-Bromo-9-Anthrylmthyl Methacrylate (BAMMA) 10-Bromo-9-anthracenecarboxaldehyde was synthesized as follows; anthrone (5 g, Aldrich) was slurried in DMF (70 d) and cooled with an ice/water mixture. POBr, (5 g, Pfaltz and Bauer) was added slowly to the

Surface energy gradient driven convection for generating nanoscale and microscale patterned polymer films using photosensitizers

“…There is no difference in the spectra taken after photoexposure compared with the one taken before the exposure. This result agrees with the Hargreave's statement that there is no difference between IR spectra of light exposed and unexposed anthracene if only endoperixde formation has occurred because of the weak influence of OO on any dipole moment . Once the photoexposed sample has been thermally annealed, two new peaks appear and grow at 1650–1700 cm −1 and 3250–3620 cm −1 , which correspond to a ketone stretch and hydroxyl stretch, respectively.…”

“…This result agrees with the Hargreave's statement that there is no difference between IR spectra of light exposed and unexposed anthracene if only endoperixde formation has occurred because of the weak influence of OAO on any dipole moment. 41,42 Once the photoexposed sample has been thermally annealed, two new peaks appear and grow at 1650-1700 cm 21 and 3250-3620 cm 21 , which correspond to a ketone stretch and hydroxyl stretch, respectively. Both the ketone and hydroxyl groups are common functional groups resulting from polymer oxidation.…”

Polymerizable anthracene derivatives for labeling emulsion copolymers

“…The synthesis of 4 was first reported by Hargreaves 18. Our approach to the synthesis of 4 is based on the previously described synthesis19 of 9‐hydroxymethyl‐10‐methyl An 9‐OH from anthraquinone, a one‐pot preparation involving the addition of two equivalents of methyl lithium to form the dianion of 8 , followed by the addition of aqueous sulfuric acid to yield 9‐OH .…”

Artificial photosynthetic antenna-reaction center complexes based on a hexaphenylbenzene core

“…The 4-iodo benzal dehyde, 4-bromobenzal dehyde, methyl 4-formyl benzoate, methyl 4-iodo benzoate, 4,4'-di bromo benzil, tetra phenylcylo penta dienone, 1-ethy nyl-3,5-dimethoxy benzene, phenyl acetylene, allyl palladium(II) chloride dimer, bis(triphenyl phosphine) palladium(II) chloride, tetrakis (triphenyl phosphine) palladium(0), quinu clidine, piperidine, tri-tert-butyl phos phine, diiso butyl aluminum hydride (1 M in hexane), n-butyl lithium (2.86 M in hexane), tert-butyl carbamate, and C 60 were commercially available and were used without purifi cation. The 5-(2,4,6-trimethyl phenyl) dipyrromethane [50], 3-(4-bromo phenyl)-2,4,5-triphenylcyclopentadienone [51], 1,3-bis(4-bromophenyl)-2propa none [52], and 9-bromo anthraldehyde [53,54] were synthesized by published methods.…”