Flash-synthesis of low dispersity PPV via anionic polymerization in continuous flow reactors and block copolymer synthesis

Abstract

Low dispersity poly[2-methoxy-5-(3 ',7 '-dimethyloctyloxy)]-1,4-phenylenevinylene (MDMO-PPV) with well-defined end-groups is made available by performing the anionic polymerization in a continuous tubular reactor under flash chemistry conditions. The anionic polymerization was carried out via the sulfinyl (Vanderzande) precursor route, following a protocol previously established. Flash flow chemistry allowed now to not only control the microstructure, but also the disperisty of the PPV efficiently. Further, this is the first time that premature termination of PPV anionic polymerization could be observed. Only at ultra-low reaction times in the order of tens of miliseconds products can be observed that have not reached full monomer conversion, redering this type of polymerization one of the fastest polymerizations known. Due to the efficient mixing in the tubular reactors, dispersities of 1.2 could be reached at such low residence times, which is unachievable in conventinal batch-wise chemistry. In a second step, a block copolymer was formed of the precursor PPV and tert-butyl acrylate (tBuA), which is further converted into an amphiphilic block copolymer of PPV with poly(acrylic acid) (PAA). Self-assembly of the PPV-b-PAA block copolymer in a continuous tubular reactor resulted in micelles with a number average diameter of 170 nm.