Macroreticular porous polymer

For the liquid phase kinetic studies of esterification, with a few exceptions [402,435—437] only the standard (non-porous, see Sect. 1.2.5) ion exchangers were used. The macroreticular (porous) ion exchangers with a large inner surface area are prefered for vapour phase reactions, especially in more recent studies [436—443]. The authors claimed that diffusion was not the limiting process under their conditions. This observation cannot be generalised, however, and even with vapour phase reactions and macroreticular polymers, the possibility of transport limitations through the pores or the polymer mass cannot be excluded a priori. 

TABLE 7.2 USE OF MACRORETICULAR RESINS IN ANALYSIS OF WATER (29) OVER-ALL RECOVERY EFFICIENCY OF THE POROUS POLYMER METHOD OF ANALYSIS FOR ORGANICS IN WATER AT THE 10- TO 100-ppb LEVEL1... 

The use of organic supports (macroreticular/macro-porous polymers) as carriers for an organometallic complex, which by itself may serve as the catalyst precursor complex, has been widely studied. The polymers must be macroporous, providing a highly accessible internal surface area. 

If MX reacts with porous polymers, accessible pores are filled first. Such overgrown pores, which are associated with filling and shielding of the crosslinked macromolecule, is evidence for the MX contribution to a supramolecular buildup of macroligands. Thus it is impossible to predict the effect of a macrohgand pore size on complex formation for macroreticular glycidyl methacrylate-ethylene glycol dimethacrylate copolymer (Fig. 2) since the material has a bimodal and even polymodal pore distribution in radius. Nevertheless, it was shown that insertion of [RhCl(CO)2]2 in a polyamide is accompanied by a shift of the pore size to lower values some... 

Macroporous or macroreticular polystyrenes have also been used as catalyst supports. (The terms macroporous and macroreticular are synonomous. They originated in different laboratories.) Macro-porous polymers are prepared by suspension polymerization of... 

Truly porous, synthetic ion exchangers are also available. These materials retain their porosity even after removal of the solvent and have measurable surface areas and pore size. The term macroreticular is commonly used for resins prepared from a phase separation technique, where the polymer matrix is prepared with the addition of a hq-uid that is a good solvent for the monomers, but in which the polymer is insoluble. Matrices prepared in this way usually have the appearance of a conglomerate of gel-type microspheres held together to... 

The resins studied (Rohm and Haas and Ionac) were all functionalized, cross-linked, styrene polymers with the exception of poly (4-vinyl-pyridine). Porous, macroreticular resins included the polymeric analogs of N,2V-dimethylbenzylamine (A21 polyDMBA, Rohm and Haas), N,N-dimethylaniline, and l-phenyl-2- (N,2V-dimethylamino) ethane (poly-Alipham), The last two materials were prepared in this laboratory. Nitrogen content of the porous resins was 4.1, 2.5, and 2.6 mequiv/gram, respectively. Poly(4-vinylpyridine) (6.9 mequiv/gram) had a gel-type structure. 

However, in the 2-ethylhexanol, the sodium and tetraethylammonium borohydrides are, in general, more reactive than the polymer-bound boro-hydrides. Of the resins, those polymers having the styrene-DVB skeletal backbone (A-26 and IRA-400) offer some advantage over the acrylate-DVB-based resin (XE-279 and IRA-458). Of the styrene-DVB resins, the macroreticular resin (A-26) gives the best reduction, particularly at an elevated temperature. Both sodium borohydride and tetraethylammonium borohydride appeared to have limited solubility at this level in 2-ethylhexanol. However, since 2-ethylhexanol is more viscous and less polar than ethanol, reactions involving the porous ion-exchange resins would be somewhat slower than the corresponding reduction with soluble borohydrides. 

Rollman and co-workers have reported a study on Rh elution from polymer supports where the Rh was anchored to porous macroreticular polymer supports based on polystyrene cross-linked through divinylbenzene or ethyleneglycoldimethacrylate via dibutylphenylphosphine or AW-dimethyl-benzylamine groups. When a flow reactor at 85-100 °C and 5-10 MPa H2/CO was used Rh concentrations of 0.2-17 x 10 M were observed in the effluent. Increasing metal loadings, CO pressure, or the polarity of the solvent caused a corresponding increase in Rh loss while increasing temperature decreased metal loss. If these results are representative of the... 

In nearly all of our investigations we used macro-porous (macroreticular) polymers. For details on the structure of macroporous polymers see Refs. (43,44). Macroporous polymers consist of primary particles (so-called nuclei) grown together during polymerization. 

Millar, J. A., Smith, D. G., Marr, W. E., and Kresmarm, T. R. E. Solvent modified polymer networks. Part 1. The preparation and characterization of expanded-networks and macro-porous styrene-DVB copolymers and their sulfonates. J Cherw Soc, pp. 218-225 (1963). Kun KA, Kunin R. Macroreticular resins III. Formation of macroreticular styrene-divinyl-benzene copolymers. JPolym Sci, PartAl, Polym Chem, 6,2689-2701 (1968). 

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