Method for the Preparation of Monodisperse High Molecular Weight Polymers (21062)
A novel method has been developed whereby monodisperse high molecular weight polymers (> 500,000 g/mol) can be prepared from a variety of synthetic, normally disperse high molecular weight polymers. This mechanical process is applied directly to the polymer and does not involve synthetic or chemical modifications. Improved properties are anticipated with reduced polydispersity in plastics, textile fibers, optical media, biomedical, electronic and specialty polymers.
ADVANTAGES: A direct and potentially low cost processto improve polymer properties of lower quality polydisperse resins without chemical modification
SUMMARY:Polymerization reactions generally yield products of varying polydispersity (Mw/Mn) containing a range of low to high molecular weight components. Polymer properties are controlled to a large degree by the polymer molecular weight distribution. Properties, such as mechanical strength and environmental stability, generally improve with low polydispersity and high molecular weight. Anionic living polymerizations can afford high molecular weight materials with polydispersity indices (PDI) of 1.10-1.30. However indices below 1.2 for high molecular weight polymers are generally difficult to obtain.
The present invention utilizes a unique device that generates mechanical extensional forces to reduce the PDI of high molecular weight polymers. High molecular weight polyacrylamide, polydimethylacrylamide and poly(ethylene oxide) with broad PDI can be converted to narrow PDI high polymers. Thus, polyacrylamide (Mw 4.1 x 106 g/mol, PDI 1.42) upon treatment affords reduced PDI polymer (Mw 7.5 x 105 g/mol, PDI 1.12). Similarly poly(ethylene oxide), (Mw 2.7 x 106 g/mol, PDI 1.59) yields product with Mw 2.9 x 105 g/mol, PDI 1.13. Key process parameters have been identified and the method is amenable to scale-up and continuous operation. The procedure appears general and applicable to a wide range of polymers.
STATUS: U. S. Patent No. 7,026,414 has issued.
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