We report the thermoreversible viscoelastic properties of a supramolecular ion gel. Two building blocks were used to form “supramacromolecules”. An ABA triblock copolymer ( M n = 50 000, poly(2-vinylpyridine)-b-poly(ethyl acrylate)-b-poly(2-vinylpyridine)) (P2VP−PEA−P2VP), with a mole ratio of 0.1/0.8/0.1 as a telechelic polymer, and a poly(4-hydroxystyrene) (PHS) homopolymer, with M n = 6600 as a connector, form a physical gel via hydrogen bonding between P2VP and PHS. The thermally stable, hydrophobic ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMITFSI) provided a good solvent medium for PEA from room temperature up to at least 160 °C. A solution containing 10 wt % P2VP−PEA−P2VP and 4% PHS was a liquid at elevated temperatures but on cooling formed a network at 141.5 °C. Dynamic shear moduli obtained as a function of frequency at various temperatures from 30 to 160 °C could be superposed to form excellent master curves, with a distinct plateau modulus extending over more than 11 orders of magnitude in frequency. The longest relaxation time inferred from the time−temperature superposition shift factors showed a similar 11 order of magnitude increase on cooling. This remarkable temperature sensitivity of the supramacromolecular ion gel is attributed to the formation of multiple hydrogen bonds between a given P2VP block and PHS cross-linker. A hydrogen bond energy of 13 kJ/mol was estimated from temperature-dependent FTIR measurements, and a straightforward analysis yielded an estimate of the number of hydrogen bonds per P2VP block as a function of temperature. This system is distinct from other supramolecular hydrogen-bonded polymers, and from hydrophobically modified associating polymers, in that below the gelation temperature the number of physical cross-links is independent of temperature, but the strength of each association, namely, the number of active hydrogen bonds within a particular cross-link site, increases strongly on cooling.

The Archimedean tiling (3 2 .4.3.4) is a regular but complex polygonal assembly of equilateral triangles and squares. This tiling pattern with mesoscopic repeating distance has been found for an ABC star-branched three-component polymer composed of polyisoprene, polystyrene, and poly(2-vinylpyridine). In this structure the environment of a molecule splits into multiple sites and two microdomains with different sizes and shapes are formed for one component. This complexity is the first observation in complex polymer systems and can lead to a new type of mesoscale self-organization. The tiling pattern has been observed for the other materials on much shorter length-scale; therefore, the experimental fact observed in the present study is demonstrating that the complexity is universal over different hierarchies.

Microphase-separated structures of diblock copolymers with narrow molecular weight distributions but with various composition distributions were investigated. Monodisperse nine parent block copolymers composed of polystyrene and poly(2-vinylpyridine) having almost the same molecular weight but with different polystyrene volume fraction, φs, covering 0.1-0.9, were prepared. Successively they were blended variously to produce samples with various composition distributions but with constant average composition; that is, φ s was kept constant at approximately 0.5. Structures from solvent-cast and well-annealed films were observed through transmission electron microscopy and small-angle X-ray scattering. It has been found that the blends with wide composition distributions show periodic alternating lamellar structure up to 1.7 in terms of M w(S)/Mn(S), where Mw(S) and Mn(S) denote weight-average and number-average molecular weights of polystyrene block, respectively, and that the microdomain spacing increases with increase of polydispersity of each block. Further, it was clarified that the blend shows macrophase separation in between two kinds of regular microphase-separated structures if M w(S)/ Mn(S) reaches approximately 1.8.

A new nanophase-separated structure with parallel double periodicity has been identified for an undecablock terpolymer in bulk. The polymer includes two long poly(2-vinypyridine) (P) chains on each end, with five short polyisoprene (I) and four short polystyrene (S) chains at the center. This polymer exhibits a hierarchical lamellar structure with two crystallographic periods: 88 nm and 16 nm. The 88 nm period includes one thick P lamella and five thin I-S-I-S-I lamellae, of extremely high orientation.