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Polyesters (PEs) are sustainable alternatives for conventional polymers owing to their potential degradability, recyclability, and the wide availability of bio-based monomers for their synthesis. Herein, we used a one-pot, one-step self-switchable polymerization linking the ring-opening alternating copolymerization (ROAC) of epoxides/cyclic anhydrides with the ring-opening polymerization (ROP) of L-lactide (LLA) to synthesize PE-based hot-melt adhesives with a high bio-based content. In the cesium pivalate-catalyzed self-switchable polymerization of glutaric anhydride (GA), butylene oxide (BO), and LLA using a diol initiator, the ROAC of GA and BO proceeded whereas the ROP of LLA simultaneously proceeded very slowly, resulting in a copolyester consisting of poly(GA-alt-BO) and poly(L-lactide) (PLLA) segments with tapered regions, that is, PLLA-tapered block-poly(GA-alt-BO)-tapered block-PLLA (PLLA-tb-poly(GA-alt-BO)-tb-PLLA). Additionally, a series of tapered-block or real-block copolyesters consisting of poly(anhydride-alt-epoxide) (A segment) and PLLA (B segment) with AB-, BAB-, (AB)3-, and (AB)4-type architectures of different compositions and molecular weights were synthesized by varying the monomer combinations, alcohol initiators, and initial feed ratios. The lap shear tests of these copolyesters revealed an excellent relationship between the adhesive strength and polymer structural parameters. The (AB)4-type star-block copolyester (poly(GA-alt-BO)-tb-PLLA)4 exhibited the best adhesive strength (6.74 ± 0.64 MPa), comparable to that of commercial products, such as PE-based and poly(vinyl acetate)-based hot-melt adhesives.

Nanoscale three-dimensional (3D) network morphologies, such as those represented by gyroids accessed by the self-assembly of block copolymers, are highly attractive platforms for the fabrication of nanostructured materials. However, it remains challenging to access such morphologies, especially in the sub-10 nm domain spacing region. Herein, we systematically investigated the microphase separation behaviors of biobased sugar–terpenoid hybrid block co-oligomers (BCOs) with different molecular parameters, including their volume fractions, the linker structures between the blocks, and the stereochemistries of the terpenoid blocks. The BCOs were synthesized using the azido–alkyne click reaction of propargyl-β-d-glucopyranoside with azido-functionalized farnesol, phytol, DL-α-tocopherol, and d-α-tocopherol, to ensure a well-defined molecular structure without any molecular weight distribution. Through X-ray scattering screening, we found that tocopherols, when combined with a glucose unit, yield BCOs capable of forming gyroid and hexagonally perforated lamellar (HPL) 3D network morphologies with ultrasmall domain spacings of ∼10 nm. Remarkably, HPL, which is known as a metastable phase in block copolymers, was obtained in both the bulk and film states. The nature of the linker structure and the stereochemistry of the tocopherol hydrocarbon chain were found to influence the resulting morphology and the long-range order of the nanostructures. We expect this study to contribute to the molecular design of precise block copolymers and the construction of intricate nanostructural templates with ultrasmall feature sizes.

The redox behaviors of macrocyclic molecules with an entirely π-conjugated system are of interest due to their unique optical, electronic, and magnetic properties. In this study, defect-free cyclic P3HT with a degree of polymerization (DPn) from 14 to 43 was synthesized based on our previously established method, and its unique redox behaviors arising from the cyclic topology were investigated. Cyclic voltammetry (CV) showed that the HOMO level of cyclic P3HT decreases from –4.86 eV (14 mer) to –4.89 eV (43 mer), in contrast to the linear counterparts increasing from –4.94 eV (14 mer) to –4.91 eV (43 mer). During the CV measurement, linear P3HT suffered from electro-oxidation at the chain ends, while cyclic P3HT was stable. ESR and UV–Vis–NIR spectroscopy suggested that cyclic P3HT has stronger dicationic properties due to the interactions between the polarons. On the other hand, linear P3HT showed characteristics of polaron pairs with multiple isolated polarons. Moreover, the dicationic properties of cyclic P3HT were more pronounced for the smaller macrocycles.

Silver nanoparticles (AgNPs) are used in a wide range of applications, and the size control and stability of the nanoparticles are crucial aspects in their applications. In the present study, cyclized poly(ethylene glycol) (c-PEG) with various molecular weights, along with linear PEG with hydroxy chain ends (HO–PEG–OH) and methoxy chain ends (MeO–PEG–OMe) were applied for the Tollens’ synthesis of AgNPs. The particle size was significantly affected by the topology and end groups of PEG. For example, the size determined by TEM was 40 ± 7 nm for HO–PEG5k–OH, 21 ± 4 nm for c-PEG5k, and 48 ± 9 nm for MeO–PEG5k–OMe when the molar ratio of PEG to AgNO3 (ω) was 44. The stability of AgNPs was also drastically improved by cyclization; the relative UV–Vis absorption intensity (A/A0 × 100%) at λmax to determine the proportion of persisting AgNPs in an aqueous NaCl solution (37.5 mM) was 58% for HO–PEG5k–OH, 80% for c-PEG5k, and 40% for MeO–PEG5k–OMe, despite the fact that AgNPs with c-PEG5k were much smaller than those with HO–PEG5k–OH and MeO–PEG5k–OMe.

Block copolymers (BCPs) have garnered considerable interest due to their ability to form microphase-separated structures suitable for nanofabrication. For these applications, it is critical to achieve both sufficient etch selectivity and a small domain size. To meet both requirements concurrently, we propose the use of oligosaccharide and oligodimethylsiloxane as hydrophilic and etch-resistant hydrophobic inorganic blocks, respectively, to build up a novel BCP system, i.e., carbohydrate-inorganic hybrid BCP. The carbohydrate-inorganic hybrid BCPs were synthesized via a click reaction between oligodimethylsiloxane with an azido group at each chain end and propargyl-functionalized maltooligosaccharide (consisting of one, two, and three glucose units). In the bulk state, small-angle X-ray scattering revealed that these BCPs microphase separated into gyroid, asymmetric lamellar, and symmetric lamellar structures with domain-spacing ranging from 5.0 to 5.9 nm depending on the volume fraction. Additionally, we investigated microphase-separated structures in the thin film state and discovered that the BCP with the most asymmetric composition formed an ultrafine and highly oriented gyroid structure as well as in the bulk state. After reactive ion etching, the gyroid thin film was transformed into a nanoporous-structured gyroid SiO2 material, demonstrating the material’s promising potential as nanotemplates.

The topology effects of cyclization on thermal phase transition behaviors were investigated for a series of amphiphilic Pluronic copolymers of both hydrophilic–hydrophobic–hydrophilic and hydrophobic–hydrophilic–hydrophobic block sequences. The dye solubilization measurements revealed the lowered critical micelle temperatures (TCMT) along with the decreased micellization enthalpy (ΔHmic) and entropy (ΔSmic) for the cyclized species. Furthermore, the transmittance and dynamic light scattering (DLS) measurements indicated a block sequence-dependent effect on the clouding phenomena, where a profound decrease in cloud point (Tc) was only found for the copolymers with a hydrophilic–hydrophobic–hydrophilic block sequence. Thus, the effect of cyclization on these critical temperatures was manifested differently depending on its block sequence. Finally, a comparison of the linear hydroxy-terminated, methoxy-terminated, and cyclized species indicated the effect of cyclization to be unique from a simple elimination of the terminal hydrophilic moieties.

Nanofibrillated bacterial cellulose (NFBC), a type of cellulose nanofiber biosynthesized by Gluconacetobacter sp., has extremely long (i.e., high-aspect-ratio) fibers that are expected to be useful as nanofillers for fiber-reinforced composite resins. In this study, we investigated a composite of NFBC and poly(methyl methacrylate) (PMMA), a highly transparent resin, with the aim of improving the mechanical properties of the latter. The abundant hydroxyl groups on the NFBC surface were silylated using 3-(methacryloyloxy)propyltrimethoxysilane (MPTMS), a silane coupling agent bearing a methacryloyl group as the organic functional group. The surface-modified NFBC was homogeneously dispersed in chloroform, mixed with neat PMMA, and converted into PMMA composites using a simple solvent-casting method. The tensile strength and Young’s modulus of the composite increased by factors of 1.6 and 1.8, respectively, when only 0.10 wt% of the surface-modified NFBC was added, without sacrificing the maximum elongation rate. In addition, the composite maintained the high transparency of PMMA, highlighting that the addition of MPTMS-modified NFBC easily reinforce PMMA. Furthermore, interactions involving the organic functional groups of MPTMS were found to be very important for reinforcing PMMA.

Herein, we report the Suzuki–Miyaura catalyst-transfer polycondensation (SCTP) of triolborate-type carbazole monomers, i.e., potassium 3-(6-bromo-9-(2-octyldodecyl)-9H-carbazole-2-yl)triolborate (M1) and potassium 2-(7-bromo-9-(2-octyldodecyl)-9H-carbazole-2-yl) triolborate (M2), as an efficient and versatile approach for precisely synthesizing poly[9-(2-octyldodecyl)-3,6-carbazole] (3,6-PCz) and poly[9-(2-octyldodecyl)-2,7-carbazole] (2,7-PCz), respectively. The SCTP of triolborate-type carbazole monomers was performed in a mixture of THF/H2O using an initiating system consisted of 4-iodobenzyl alcohol, Pd2(dba)3•CHCl3, and t-Bu3P. In the SCTP of M1, cyclic by-product formation was confirmed, as reported for the corresponding pinacolboronate-type monomer. By optimizing the reaction temperature and reaction time, we successfully synthesized linear end-functionalized 3,6-PCz for the first time. The SCTP of M2 proceeded with almost no side reaction, yielding 2,7-PCz with a functional initiator residue at the α-chain end. Kinetic and block copolymerization experiments demonstrated that the SCTP of M2 proceeded in a chain-growth and controlled/living polymerization manner. This is a novel study on the synthesis of 2,7-PCz via SCTP. By taking advantage of the well-controlled nature of this polymerization system, we demonstrated the synthesis of high-molecular-weight 2,7-PCzs (Mn = 5–38 kg mol−1) with a relatively narrow ÐM (1.35–1.48). Furthermore, we successfully synthesized fluorene/carbazole copolymers as well as 2,7-PCz-containing diblock copolymers, demonstrating the versatility of the present polymerization system as a novel synthetic strategy for well-defined polycarbazole-based materials.

Cellulose is a useful polymer for human life. Therefore, its production in space will be necessary to support human habitation in the near future. In this paper, we studied the protocol and culture vessels for bacterial cellulose production in space using Komagataeibacter, as it is the most convenient method to produce cellulose in space. Since aerobic respiration is required for the cellulose production, we developed new gas-permeable culture vessels that can be used in the International Space Station (ISS). The bacterial cells were cultured on the ISS under microgravity and bacterial cellulose was successfully produced. This study shows that cellulose pellicle formation by Komagataeibacter is free from antigravitaxis and cellulose production is possible under the microgravity. [ABSTRACT FROM AUTHOR]