No abstract

Oxyanions form a new class of catalysts for group-transfer polymerization (GTP) of acrylic monomers.Active catalysts in this class include aliphatic and aromatic carboxylates, phenolates, sulfinates, phosphinates, sulfonamidates, perfluoroalkoxides, nitrite, and cyanate. Catalytic activity is found in oxyanions whose conjugate acids have a p (in DMSO) within the range 4.5-23. Best results in terms of livingness and polydispersity of the resulting polymers are obtained with the lowest operable concentrations of the most active catalysts and with somewhat higher concentrations of catalysts of moderate activity. Bioxyanions (1:1 complexes of oxyanions with their conjugate acids) also are active but show reduced activity compared to the corresponding monooxyanions. They give better control of molecular weight than is obtained with the corresponding monooxyanions. In contrast to the more potent catalysts, the weaker catalysts show little activity at temperatures substantially below room temperature. Relative catalyst efficiency correlates well with pKa(DMSO) of the conjugate acids of the corresponding catalysts. The stereochemistry of PMMA prepared with oxyanion catalysts does not differ substantially from that of PMMA prepared with bifluoride catalysis.

No abstract

No abstract

No abstract

No abstract

No abstract

Photolithography at 157 nm requires development of new photoresists that are highly transparent at this wavelength. Transparent fluoropolymer platforms have been identified which also possess other materials properties required for chemically amplified imaging and aqueous development. Polymers of tetrafluoroethylene (TFE), a fluoroalcohol-substituted norbornene and an acid-labile acrylate ester show the best combination of properties. A solution, semibatch, free-radical polymerization process was developed allowing synthesis of the terpolymers on a multikilogram scale. Further property enhancements may arise from replacing the norbornene with functionalized tricyclononenes. Formulated resists have been imaged in a 157 nm microstepper. #