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The bicyclic guanidine 1,5,7- triazabicyclo[4.4.0]dec-5-ene (TBD) is an effective organocatalyst for the formation of amides from esters and primary amines. Mechanistic and kinetic investigations support a nucleophilic mechanism where TBD reacts reversibly with esters to generate an acyl-TBD intermediate that acylates amines to generate the amides. Comparative investigations of the analogous bicyclic guanidine 1,4,6-triazabicyclo[3.3.0]oct-4-ene (TBO) reveal it to be a much less active acylation catalyst than TBD. Theoretical and mechanistic studies imply that the higher reactivity of TBD is a consequence of both its higher basicity and nucleophilicity than TBO as well as the high reactivity of the acyl-TBD intermediate, which is sterically prevented from adopting a planar amide structure.

Polymerized ionic liquids (PILs) are a platform for fundamental studies of structure-property relationships in single ion conductors, with potential applications in energy storage and conversion. The synthesis, thermal properties, and ionic conductivities of homologous, narrow dispersity styrenic PILs are described. Hydrophilic poly(4-vinylbenzyl alkylimidazolium chloride) (PVBn(alkyl)ImCl) homopolymers with constant average degrees of polymerization were synthesized by post-synthetic functionalization of a poly(4-vinylbenzyl chloride) (M n ¼ 15.9 kg/mol, M w /M n ¼ 1.34) master batch with N-alkylimidazoles (alkyl ¼ ACH 3 (Me), AC 4 H 9 (Bu), and AC 6 H 13 (Hex)). The chloride counterions of PVBnHexImCl were exhaustively metathesized with BF À 4 , PF À 6 , and bis(trifluoromethanesulfonyl)imide (TFSI À ) to yield a series of hydrophobic PILs. Thermogravimetric analyses indicate that PVBn(alkyl)ImCl homopolymers are unstable above 220 C, whereas the hydrophobic PILs remain stable up to 290 C. The glass transition temperatures (T g ) decrease with both increasing alkyl side-chain length and increasing counterion size, exemplified by T g ¼ 9 C for PVBnHexImTFSI. Hydrophilic PILs exhibit high ionic conductivities (as high as $0.10 S cm À1 ) that depend on the relative humidity, water uptake, and the PIL side chain length. The hydrophobic PILs exhibit lower conductivities (up to $5 Â 10 À4 S cm À1 ) that depend predominantly on the polymer T g , however, counterion size and symmetry also contribute.Additional Supporting Information may be found in the online version of this article.

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Perfectly regioregular α,ω-telechelic poly(1,4-butadienes) (1,4-PBlin or B) bearing terminal alkoxyamine functionalities are synthesized by chain transfer ring-opening metathesis polymerization (ROMP-CT) of trans,trans,cis-1,5,9-cyclododecatriene in the presence of an acyclic olefin chain transfer agent. We demonstrate that these polydisperse, telechelic 1,4-PBlin polymers are macromolecular initiators for nitroxide-mediated polymerizations (NMP) of styrene and isoprene to produce SBS, IBI, and SIBIS block copolymers (S = poly(styrene) and I = poly(4,1-isoprene)). Selected SBS and SIBIS multiblock copolymers were hydrogenated to produce microphase-separated multiblock copolymers containing polydisperse, high-density poly(ethylene) (Elin) segments inaccessible by other polymerization techniques.