| Synthetic routes to 1-substituted 4-vinylbenzocyclobutenes (VBCBs) were developed. The VBCBs were generated by a [2+2]-cycloaddition between benzyne and a vinyl-substituted compound. Routes to aromatic halogenation of 1-substituted-BCBs were explored. The use of a substrate bearing an aromatic halogen for the cycloaddition reaction was a more efficient route to 1-substituted-4-halo-BCBs than post-cycloaddition halogenation. Conversion of the aromatic halogen to a vinyl group using both a Wittig reaction and a Kumada coupling with vinyl bromide was examined with the latter being the preferred route.;These VBCB monomers were copolymerized with styrene derivatives via atom transfer radical polymerization (ATRP). The VBCB monomer was present in 5--20 mol% to act as a thermally induced crosslinker. Random copolymerizations of 1-ethoxy-4-vinylbenzocyclobutene (VEBCBE) with both styrene and 2,3,4,5,6-pentafluorostyrene (PFS) were conducted. Polymerizations using VEBCBE were conducted at polymerization temperatures of 60 ºC or less to prevent premature reaction of the BCB unit. Differential scanning calorimetry (DSC) analysis was used to characterize the ring-opening behavior of the BCB compounds. Dropwise addition of polymers containing these VBCB units to a heated solvent allowed preparation of spherical, polymeric nanoparticles at lower temperatures than those previously described in the literature.;The polymerization behavior of VEBCBE was examined. The chain transfer constant for this compound in the free radical polymerization of both styrene and PFS in bulk at 60 ºC was measured as Cx= 0.006 and 0.015, respectively. The reactivity ratios for PFS and VEBCBE at 70 ºC in bulk free radical polymerization were also measured. The polymerization exhibited an alternating tendency with r1=r VEBCBE=0.05--0.12, r2= rPFS=0.504--0.735, and r1r 2=0.025--088. |
