Invited Review in 2015

Glycosaminoglycans (GAGs) are one of the most important polysaccharide in the living systems. However, preparation of GAGs is difficult owing to the complex structure and high molecular weight. In order to obtain the GAGs’ materials with a practical way, we investigated a new approach to mimic GAGs using polymer chemistry. We reviewed the syntheses of GAGs of the previous reports and the glycopolymers having GAGs moieties, including our GAGs' mimic polymers.

In this review, we show that using two-dimensional (2D) samples suitable for atomic force microscopy (AFM) observation, especially Langmuir–Blodgett films, molecular images of various polymer structures could be obtained by tapping-mode AFM. The molecular-level observations included isolated polymer chains and their movements on substrates, 2D folded-chain crystals and their melting behavior, crystallization behavior of single isolated chains, supramolecular multistranded stereocomplex and chain packing in monolayers. The molecular-level information obtained by the direct observations should greatly improve our understanding of polymer science.

Susceptible situation of water molecules in the vicinity of lopsidedly charged copolymer films (upper) and a zwitterionic copolymer film. The charge-neutralized polymer surface is less perturbative to the structure of vicinal water. The image first published in Kobunshi 39, 445 (Hot Topics) (2014).

This review focuses on redox-induced molecular actuation in macromolecular and self-assembled systems. Effective amplifications of conformational changes of unit molecular part are explored on the basis of three categories: polymeric system; molecular interactions; and self-assembled system. The importance of highly ordered structures is suggested to effectively amplify conformational change of small molecular unit into macroscopic deformation of bulk materials. Finally, future outlook toward electrochemical soft actuators and tips to prepare stimuli-responsive molecular assemblies, which undergo amplification in conformational change of constituent molecules, are provided.

The establishment of a Lewis acid-mediated selective propoxylation reaction using a specific borane catalyst enabled the synthesis of a novel class of PPG with an increased primary hydroxyl content of up to 70%. In addition, we developed a high yielding continuous process for producing the new PPG with a low amount of by-products by using tube reactors combined with film evaporators for by-product removal. Our new PPG achieves an excellent balance between reactivity and humidity resistance. As a result, it has important advantages for a broad area of polyurethane applications.

For long-lasting implants of an artificial hip joint, it is necessary to reduce the wear of the acetabular liner made with polyethylene (PE). An articular cartilage-mimicking technology has been developed by grafting poly(2-methacryloyloxyethyl phosphorylcholine (MPC)) onto a highly cross-linked PE using photoinduced polymerization. The thickness of the poly(MPC) graft layer is 100–200 nm. The poly(MPC)-grafted PE has been introduced on an artificial hip joint system as a liner for lubrication. This artificial hip joint has been used clinically since 2011 and implanted on over 20 000 patients.