Self-supporting Rods, Discs and Plugs

The synthesis of self-supporting monolithic cylindrical rods ( lcmxlOcm) again with compositions and morphologies similar to resins has been reported [51]. These can also be prepared with a texture that allows each rod to be cleaved into discs. ( lcmx0.2cm, mass 250-500mg) (Fig. 1.10). The latter can be handled by a robot arm and soHd phase synthesis on one disc allows up to 0.5 mmole of a single compound to be produced. Similar disc and alternative shaped macroscopic supports have now been reported [52-54]. 

Recently this problem has been circumvented by the synthesis of so-called plugs which are in effect conventional resins that have been sintered and melt fused with a polyalkene (Fig. 1.11) [55]. Each cylindrical plug is 7 mmxlO mm and the level of polyalkene employed is low enough for much of the interstitial space between the resin beads to be retained hence providing ready access by solvent and reagents to the core of the plug. 

In principle any pre-functionalized resin can be formed into a plug and the monoliths show good solvent resistance except to e.g. hot toluene or xylene. The size of each plug makes them easily manipulated by a robot and use in scavenging situations seems very attractive. Some applicahons have already been reported [56] and the monoliths will be made available as StratoSphere Plugs via Polymer Laboratories (Church Stretton, UK). 

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