Abstract Cellulose esters with long-chain alkyl groups are promising sustainable materials because their hydrophobicity and thermal stability can be tuned through chemical modification. We report a mechanochemical transacylation method for synthesizing cellulose laurates using vinyl laurate in a dimethyl sulfoxide/sodium hydroxide medium. The process enables the efficient modification of 0.81 g of cellulose and yields products with degrees of substitution ranging from 0.50 to 2.94 under different designated conditions. Structural analysis by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) confirmed successful esterification and reduced crystallinity. The physical properties varied systematically with substitution level, with higher substitution improving thermal stability and reducing wettability, providing opportunities to tailor performance. Response surface methodology, which is based on a five-level, four-factor central composite rotatable design, was applied to study the interactive effects of synthesis parameters and optimize the degree of substitution. The experimental results closely matched the predicted values with 97.3% accuracy, demonstrating the robustness of the approach. This study establishes a green and reproducible route for producing functional cellulose esters with potential applications in bioplastics.

Abstract The development of polymer dielectrics with extremely low dissipation factors ( D f ) in the GHz range is essential for next-generation high-frequency communication and advanced semiconductor technologies. In this study, silicon-containing polyimides (PIs) were systematically synthesized through the incorporation of polysiloxane and double-decker silsesquioxane (DDSQ) units, aiming to elucidate the correlation between molecular structures, higher-order structures, and dielectric properties. Poly(amic acid) precursors were prepared using various tetracarboxylic dianhydrides and silicon-containing diamines, followed by thermal imidization to obtain PI films. Wide-angle X-ray diffraction analysis revealed the formation of periodic layered structures in polysiloxane-containing PIs and the preservation of the cage-like architecture in DDSQ-containing PIs. Dielectric measurements at 10 and 20 GHz demonstrated that the introduction of silicon-containing units reduced the dielectric constant ( D k ) to less than 3.0 because of increased free volume. Notably, the D f values of DDSQ-containing PIs were markedly lower ( ~ 0.002–0.003) than those of polysiloxane-based PIs because of the effective suppression of dipolar orientational polarization originating from the rigid and highly symmetric DDSQ framework. These findings provide an important molecular design strategy for low-loss polymer dielectrics and highlight the potential of DDSQ-based PIs as promising candidates for interlayer insulating materials in high-frequency electronic devices.

Abstract Multiblock copolymers consisting of isotactic polypropylene ( i PP) and ethylene–propylene rubber (EPM) were successfully synthesized by cross-metathesis between these polymers bearing a small number of C = C bonds in the main chain. The C = C bonds for metathesis were incorporated into the polyolefins by copolymerization with butadiene. This polymerization rate was greatly improved by the coexistence of a small amount of ethylene with the butadiene, probably because π-allyl metal species were rapidly converted to alkyl metal species by the insertion of ethylene. The cross-metathesis reaction occurred not only at the in-chain C = C bonds but also at the vinyl groups formed by the 1,2-insertion of butadiene, resulting in the formation of a long-chain branched polyolefin. Compared with the polymer blend of i PP and EPM, the obtained product showed excellent physical properties because of the partial compatibilization of the two phases. In particular, the tensile absorption energy was improved by a factor of 50 by block formation (2.8 ± 1.9 MJ/m 3 vs. 141 ± 28 MJ/m 3 ), successfully demonstrating the potential of this material as a polyolefin-based elastomer.

Abstract The dimensional characterization of ethylcellulose (cellulose ethyl ether, EC x , where x is the degree of substitution based on the number of hydroxyl groups in a repeating unit (in this study, x = 3.0 and 2.5)) with a weight-averaged molar mass ( M w ) ranging from 6.32 × 10 3 to 3.83 × 10 5 g mol –1 and a relatively narrow molar mass distribution ( M w / M n < 1.2) was studied in tetrahydrofuran (THF) at 25 °C using static light and small-angle X-ray scattering and intrinsic viscosity ([ η ]) measurements. Eleven fully substituted EC 3.0 samples with M w / M n values ranging from 1.05 to 1.22 were prepared by reacting commercially available EC 2.5 with ethyl iodide in THF at 55 °C in the presence of sodium hydride, followed by fractionation using recycling preparative size exclusion chromatography (SEC) in CHCl 3 . Furthermore, eight EC 2.5 samples with M w / M n values ranging from 1.04 to 1.19 were obtained by applying the same fractionation technique to EC 2.5 . Afterward, the z-averaged root-mean-squared radius of gyration (< S 2 > z 1/2 ) and [ η ] for the isolated EC 3.0 and EC 2.5 chains were measured and tabulated as functions of M w . Furthermore, their M w dependencies were analyzed using cylindrical wormlike chain and wormlike touched-bead models. The chain stiffness parameter (Kuhn segment length, λ –1 ), molar mass per unit contour length ( M L ), and hydrodynamic bead diameter ( d B ) were determined to be 23.1 nm, 491 g mol –1 nm –1 , and 1.8 nm for EC 3.0 and 16.5 nm, 467 g mol –1 nm –1 , and 1.1 nm for EC 2.5 , respectively. These results indicate that both EC 3.0 and EC 2.5 form semiflexible chains with moderate stiffness, primarily because of steric hindrance arising from the ethyl groups in the cellulose backbone. The monomer counter length ( l M ) was estimated to be 0.50 nm for both EC 3.0 and EC 2.5 , suggesting that the local conformation of the EC chain remains largely unaffected by x between 2.5 and 3.0. In addition, the l M value was almost equal to that (0.51–0.52 nm) of crystalline cellulose but considerably greater than that (0.33 nm) of α-1,4-linked amylose derivatives. In contrast, λ –1 and d B were influenced by x , likely because of greater steric hindrance in the main chain and desolvation around the hydroxyl groups.

Abstract Pullulan, a water-soluble polysaccharide, was grafted with short (4-mer and 6-mer) oligonucleotides containing bridged nucleic acids (BNAs) to produce self-assembled nanogels through the formation of oligonucleotide double chains. Dynamic light scattering measurements and transmission electron microscopy images revealed that oligonucleotide-grafted pullulans containing oligonucleotides with different chain lengths, sequences, and numbers of BNA substituents in water formed nanogels and that their aggregation behavior changed with temperature. Gel electrophoresis revealed that the complexation of fluorescently labeled oligonucleotides with these nanogels was possible, and flow cytometry measurements indicated that the cellular uptake of oligonucleotides was significantly enhanced when the oligonucleotides were complexed with the nanogels. Therefore, self-assembled nanogels derived from oligonucleotide-grafted polysaccharides can be applied as carriers of nucleic acids and nucleic acid-conjugated molecules for intracellular delivery.