Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain
the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in
Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles
and JavaScript.
Our recent studies on the polymerization of diazocarbonyl compounds to afford functional polymers are reviewed. In the first part of this article, Pd-mediated polymerization of various functionalized diazoacetates and unique properties of the resulting polymers due to the effects of the dense packing of the functional groups in the polymers are described. The second part of this report summarizes our recent results on the polycondensation of bifunctional diazocarbonyl compounds as monomers.
Low-modulus polypropylene (LMPP) with controlled stereoregularity showed elastic recovery. To understand the underlying mechanism, changes in the morphology of LMPP under cyclic uniaxial elongation were investigated using in situ SAXS and WAXD. During the first cycle, the undulating structure of the crystal lamellae is large, and fragmentation of the lamellae occurs. On the other hand, during the second cycle, the little fragmentation of the lamellae occurs and that only the lamellae were rotating under elongation. Based on these results, lamella fragmentation has a significant effect on the elastic-recovery rate.
The osmotic pressure during the gelation process below the overlapping concentration of prepolymers was investigated using a series of model polymer gels, namely, tetra-polyethylene glycol gels. The osmotic pressure decreased during the gelation reaction and was constant after the sol–gel transition, suggesting that the clusters grow and fill the system, at the sol–gel transition point. This representation of the sol–gel transition at the overlapping condition of the critical clusters corresponds well to the aggregation process prediction.
Active, hydrophilic, piezoelectric PLLA surface is formed by correlating processing parameters with etching and annealing as post-processing steps. Optimal design is obtained after uniaxial drawing of films for five times their length at 90 °C with 40 mm min−1 drawing rate and post-processing heat treatment at 140 °C followed by surface alkaline etching. We designed active PLLA film with high potential for intensive interactions with cells, very important for further biomedical applications, including exploring the effect of piezoelectricity on cell proliferation.
A π-conjugated polymer based on thienylene–vinylene–thienylene (TVT) units can form a thermotropic liquid-crystalline (LC) mesophase over a wide temperature range. Thermal annealing at LC temperatures strongly enhanced hole mobilities in organic field-effect transistors (OFETs) owing to improved molecular ordering. Because of its thermoplasticity, the TVT-based π-conjugated polymer can also be processed into semiconducting fine microfibers and serve as a charge transport pathway in microfiber OFETs.
Visible light-curable alginate was prepared by coupling alginate with furfurylamine. The prepared furfuryl alginate (F-Alginate) underwent gelation in the presence of a photosensitizer under visible light irradiation. The mechanical and release properties of the visible light-induced gel were similar to that of conventional Ca2+-induced cross-linked alginate. The release rate of encapsulated substances depended on their molecular weight. Cell growth was enhanced in response to a sustained release of insulin-like growth factor-1 from the F-Alginate hydrogel.
To understand the roles of mechanical and structural factors in the extracellular matrix on cancer cell migration, elasticity/porosity-tunable gel matrices of gelatinous microfibers were developed. The elasticity of fibers and the porosity of matrix were tuned with photocrosslinking conditions and degree of interfiber bonding, respectively. Highly malignant MDA-MB-231 cells showed the highest degree of MMP-independent invasion into the matrix composed of fibers with a Young’s modulus of 20 kPa and a low degree of interfiber bonding, while nontumorigenic MCF-10A cells did not show invasive behavior under the same matrix conditions.
The epoxydized soybean oil grafted with CTBN (ESO-g-CTBN) was synthesized from ring opening reaction between epoxide group and carboxyl group. The ESO-g-CTBN help to improve the fracture toughness of epoxy resin by the mechanism as shown in the figure.
Core cross-linked star-shaped poly(N-isopropylacrylamide) (PNIPAAm), which was prepared via an arm-first method by reversible addition-fragmentation chain-transfer polymerization, was shown to exhibit unique thermoresponsive behavior in water. Star polymers with ~20–35 arms with narrow molecular weight distributions apparently had a more hydrophilic nature compared with that of linear PNIPAAm, judging from their thermoresponsive behavior. Most importantly, an aqueous solution of the star PNIPAAm with carboxy ends remained transparent even at 70 °C.
