Polymers polymer-analogous

The solubHity properties of the PAG itself can play an important role in the overaH resist performance as weU (50). SolubHity differences between the neutral onium salt and the acidic photoproducts can be quite high and wHl affect the resist contrast. In fact onium salts can serve as dissolution inhibitors in novolac polymers, analogous to diazonaphthoquinones, even in the absence of any acid-sensitive chemical function (51). 

Using suitable polymers, the analogously recorded information can be erased blockwise by illumination with light of appropriate wavelength. As an eligible photosensitizer, 2,2-dimethoxy-2-phenylacetophenone has been described (171). 

There are a variety of reaction systems that allow the formation of cellulose trinitrate [9046-47-3]. HNO in methylene chloride, CH2CI2, yields a trinitrate with essentially no degradation of the cellulose chain (53). The HNO /acetic acid/acetic anhydride system is also used to obtain the trinitrate product with the fiber stmcture largely intact (51,52). Another polymer analogous reaction utilises a 1 1 mixture of HNO and H PO with 2.5% P2O5 to achieve an almost completely nitrated product (54). 

A polymer-bound analog of the p-sulfonato-calix[6]arenes is described in a Shinkai patent [31,32], which states that the hexakis(carbetoxymethyl)ether of p-sulfonatocalix[6]arene was partially nitrated, ami-nated, and fixed on crosslinked chloromethylated polystyrene. This resin is stated to absorb 108 ixg of uranium... 

The transformation of the hydrophobic periphery composed of bromo substituents into a hydrophilic wrapping of carboxylic acid functions was achieved by reacting 31 with (i) n-butyllithium and (ii) carbon dioxide. The polymer-analogous transformation provides water soluble, amphiphilic derivatives of 31 which constitute useful covalently bonded unimolecular models for micellar structures. 

Synthesis and Modification of New Acrylonitrile Polymers and Copolymers with the Use of Polymer-Analogous Transformations of the Nitrile Groups 115... 

The silyloxy-substituted precursor polymers (88) can be photocyclized in a polymer-analogous fashion to yield polymeric intermediates (90) containing the 3,6-phenanthrylene unit. These intermediates can be converted thermally to yield conjugated polyarylenevinylenes, in this case poly(3,6-phenanthrylene-vinylene) (91), a polymer that displays a long-wavelength absorption maximum at about 360 nm 1114]. 

The synthetic route represents a classical ladder polymer synthesis a suitably substituted, open-chain precursor polymer is cyclized to a band structure in a polymer-analogous fashion. The first step here, formation of the polymeric, open-chain precursor structure, is AA-type coupling of a 2,5-dibromo-1,4-dibenzoyl-benzene derivative, by a Yamamoto-type aryl-aryl coupling. The reagent employed for dehalogenation, the nickel(0)/l,5-cyclooctadiene complex (Ni(COD)2), was used in stoichiometric amounts with co-reagents (2,2 -bipyridine and 1,5-cyclooctadiene), in dimethylacetamide or dimethylformamide as solvent. 

The chemical modification of poly (2,6-dimethyl-l,4-phenylene oxide) (PPO) by several polymer analogous reactions is presented. The chemical modification was accomplished by the electrophilic substitution reactions such as bromination, sulfonylation and acylation. The permeability to gases of the PPO and of the resulting modified polymers is discussed. Very good permeation properties to gases, better than for PPO were obtained for the modified structures. The thermal behavior of the substituted polymers resembled more or less the properties of the parent polymer while their solution behavior exhibited considerable differences. 

In order to determine the necessity and/or the length of the spacer that is required to achieve liquid crystalline behavior from flexible vs. rigid polymers, we have introduced mesogenic units to the backbones of a rigid [poly(2,6-dimethyl-l,4-phenylene oxide) (PPO)] and a flexible [poly(epichlorohydrin) (PECH)] polymer through spacers of from 0 to 10 methylene groups via polymer analogous reactions. 

The attachment of mesogenic units to a polymer backbone via polymer analogous reactions is not a new concept, although they are much less frequently used than the polymerization of mesogen containing monomers. Liquid crystalline polyacrylates,... 

In contrast to the substituted PPO s, It Is theoretically possible to obtain the same substituted PECH s by homopolymerization of the corresponding mesogenic oxirane, or by its copolymerization with epichlorohydrin. We have attempted these polymerizations in order to better interpret the thermal behavior of the more complicated copolymers that we have obtained by polymer analogous reactions. Homopolymerization would be instructive because the incorporation of nonmesogenic units into liquid crystalline homopolymers doesn t as a rule change the type of mesophase obtained (5). 

These results demonstrate that side-chain liquid crystalline polymers can be synthesized by polymer analogous reactions from theoretically any polymer backbone. When the polymer backbone is rigid, as in the case of PPO, a long spacer is required both to decrease the Tg of the parent polymer and to partially decouple the... 

Employing 0.2 equiv. of polymer-bound dendritic Ti-TADDOLates of type 89 (1st and 2nd generation) enantioselectivities up to 98 2 were observed (Fig. 31). This value is comparable to those obtained in heterogeneous reactions using non-dendritic, polymer-bound analogs 88 (er up to 98,5 1,5 [ 105 ]) and with the... 

Initiator (233), and a polymer-supported analog,641 are commercially available and have found widespread use in the ring-closing metathesis (RCM) and ROMP of functionalized substrates. In addition, water-soluble variants such as (234) and (235) have been synthesized using aliphatic ionic phosphines and employed in aqueous media.642-645... 

The synthesis of block copolymers with blocks of ultralow cohesion energy densities on the basis of polystyrene-6-polybutadiene via two highly efficient polymer analogous reactions has been presented. 

---