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Topologically crosslinked polymers with rotaxane structures at the crosslinking points (rotaxane-crosslinked polymers, RCPs) have attracted great interest experimentally and theoretically. This focus review describes recent progress concerning the synthesis and applications of RCPs via four strategic approaches. Related research topics and further perspectives on RCPs are also discussed.
Isothermal crystallization of PLLA/PBA blends shows great difference to that of neat polymer. Blends have faster crystallization rate and lower melting temperature than PLLA in high-temperature region. However, blends form different crystal structures to that of neat PBA at low temperatures and have lower crystallization rate. The crystallization rate, morphology and crystal structure of neat PLLA and PBA can be modulated by mutual blending.
Cascading energy landscapes through funneling has been postulated as a mechanistic route for achieving lowest energy configuration of a macromolecular system (such as, proteins and polymers). In particular, understanding molecular mechanism of melting and crystallization of polymers is a challenging fundamental question. The structural modifications that lead to melting of PEG are investigated here. Specific Raman bands corresponding to different configurations of the PEG chain have been identified and the molecular structural dynamics of PEG melting has been addressed using Raman spectroscopy, two-dimensional Raman correlation and DFT calculations.
The electro-optical properties of the low-molecular-weight liquid crystal (LC) blue phase and the polymer-stabilized blue phase are investigated using the cyanobiphenyl homologue chiral nematic LC mixtures. It was found that the driving voltage and the switching hysteresis of blue phase were increased by polymer stabilization. Also, it was confirmed that the electro-optical rising time of blue phase was varied with the molecular parity of the n-CB homologue chiral nematic LC mixtures.
The transmittance is suddenly diminished at a critical concentration C*, and the C* shifts to the higher value as the smaller molecular weight is employed and, especially in the case of Mw of ca. 0.3 × 104, C* was not found out up to ca. 50 wt%.
UV-cured polyurethanes and linear polyurethanes are investigated for the potential use of thermo-optic waveguide materials. The thermo-optic effects of these polymer films are improved with higher contents of urethane backbones. The urethane polymers exhibit high light transmission in NIR region after deuterium-exchange reaction.
Poly(m-phenylene diethynylene)s tethering a pendant rotaxane switch were synthesized. The reversible switching behavior of rotaxane in a polymer side chain matched that of the monomer. The dynamic foldamer behavior of these polymers was controlled by solvent and rotaxane moiety. The amine-type polyrotaxanes were confirmed to favor a folded conformation in a CH2Cl2/CH3CN mixed solvent. In contrast, the ammonium salt-type polyrotaxanes exhibited only a random-coil conformation because of the ionic character in the same mixed solvent.
DNA-immobilized glass beads (DNA beads) were prepared by coating DNA-inorganic hybrid material onto glass beads. When these DNA beads were placed in an aqueous metal ion-containing solution and incubated (batch method), the DNA beads selectively accumulated the heavy and rare-metal ions, such as Cu2+, Cd2+, In3+ or La3+. Therefore, we demonstrated the accumulation of metal ions by a DNA-immobilized glass bead column (DNA column). As a result, the DNA column effectively accumulated the heavy and rare-metal ions. Furthermore, the DNA column could be recycled by washing it with an aqueous EDTA solution.
