polymers), and incorporation of polar monomers into various polyolefin classes. For example, if acrylates, vinyl esters, acrylonitrile, and the like could be incorporated into the present low-pressure polyolefin synthesis, the result would be a new family of olefin-based polymers that are likely to have major commercial significance. Of course, improvements in the present catalytic systems will have a pronounced effect on the polyolefins that are commercially available. Improvements in molecular weight distribution control (e.g., narrow molecular weight distribution), the ability to synthesize EPRs in gas-phase reactors, and the control of catalyst decay (e.g., improved efficiency) are advances that will surely occur.
Novel metathesis catalysts for the synthesis of cyclic olefins have resulted in a host of new polymeric structures. Several of these have reached commercial status (e.g., trans-poly(octenamer)). The few catalysts that are effective are often expensive and require unattractive precautions during industrial scale-up. Further advances could make this a promising area for industrial exploitation.
In the field of functionalized monomers, the trend will likely revolve around new or existing monomers via biomass, coal, or C1 conversion, as the carbon source availability changes together with economics. Improved catalysts for creating monomers from agricultural commodities or waste materials offer increasingly important opportunities. This field could benefit from the genetic engineering of specific enzyme "catalysts." Oxidative coupling of methanol to ethylene glycol and ethanol to 1,4-butanediol could open new routes to these important monomers. A new process (in progress) involving the one-step ammoxidation of propane to acrylonitrile could change the commercial position. Other possibilities—for example, utilizing shape-selective catalysts such as zeolites—could yield lower-cost routes to 4,4'-diphenol via phenol coupling. Such a molecule is of interest for liquid crystalline and engineering polymers. Improved non-phosgene routes to diisocyanates are desired. Functionalized oligomers such as hydroxyl (OH)-, amino (NH2)-, and carboxyl (COOH)-terminated polyolefins could yield important blocks for step-growth polymers (e.g., urethanes, polyesters). Functionalized fluoroolefin oligomers for inclusion in step-growth polymers could likewise offer a new variety of polymers. A non-chlorine route to siloxane polymer precursors is also desired.
In the field of polymers, a number of prior failures have been well documented in the literature, primarily resulting from the unavailability of appropriate catalysts. The reaction of acetaldehyde to yield polyvinyl alcohol is one such example. Because phosgene is highly toxic, a non-phosgene route to polycarbonate is desirable. The polymerization of phenol to a highly linear unsubstituted poly(1,4-phenylene oxide) of high molecular weight would be of interest, as would the polymerization of polyphenylene