Green Antibacterial Nanocomposites from Poly(lactide)/Poly(butylene adipate-<i>co</i>-terephthalate)/Nanocrystal Cellulose–Silver Nanohybrids

Silver nanoparticles (AgNPs) with a diameter of 3–6 nm were uniformly reacted onto the surface of nanocrystal cellulose (NCC) via complexation leading to NCC–Ag nanohybrids with an AgNP content of 8 wt %. Subsequently, antibacterial green nanocomposites containing renewable and biodegradable poly­(lactide) (PLA), poly­(butylene adipate-<i>co</i>-terephthalate) (PBAT) and NCC–Ag nanohybrids were synthesized and investigated. The PBAT as flexibilizer improved the toughness of the PLA matrix while the uniformly dispersed NCC–Ag nanohybrids enhanced the compatibility, thermal stability, crystallization, and antibacterial properties of the PLA/PBAT blends. The crystallization rate and the storage modulus (<i>E</i>′) of the green nanocomposites were increased obviously with increasing content of CNC–Ag nanohybrids. Meanwhile, notably the antibacterial activity of the PLA/PBAT/NCC–Ag nanocomposites was achieved against both Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus cells. The antibacterial performance was mainly related to the antibacterial nature of the finely dispersed NCC–Ag nanohybrids. The study demonstrates great potential of the green nanocomposites in functional packaging and antibacterial textile applications

Biobased Poly(lactide)/ethylene-<i>co</i>-vinyl Acetate Thermoplastic Vulcanizates: Morphology Evolution, Superior Properties, and Partial Degradability

Partially biobased thermoplastic vulcanizates (TPV) with novel morphology, superior properties and partial degradability were prepared by dynamic cross-link of saturated poly­(lactide) and ethylene-<i>co</i>-vinyl acetate (PLA/EVA) blends using 2,5-dimethyl-2,5-di­(<i>tert</i>-butylperoxy)­hexane (AD) as a free radical initiator. EVA showed higher reactivity with free radicals in comparison with PLA, leading to much higher gel content of the EVA phase (<i>G</i>_f‑EVA) than that of the PLA phase (<i>G</i>_f‑PLA). However, the <i>G</i>_f‑PLA increased more steeply at AD content larger than 1 wt % where the reaction of EVA approached to a saturation point. The competing reaction changed the viscosity ratio of the two components (η_PLA/η_EVA) that resulted in a novel morphology evolution of the TPV, i.e., from sea–island-type morphology to phase inversion via a dual-continuous network-like transition and finally cocontinuity again with increasing the AD content. The cross-link and phase inversion considerably enhanced the melt viscosity (η*), elasticity (<i>G</i>′) and the solid-like behavior of the PLA/EVA-based TPV. Meanwhile, superior tensile strength (σ_t = 21 MPa), low tensile set (<i>T</i>_s = 30%), moderate elongation (ε_b = 200%) and suitable stiffness (<i>E</i>′ = 350 MPa, 25 °C) were successfully achieved by tailoring the cross-link structure and phase morphology. In addition, the TPV are partially degradable in aqueous alkali. A degradation rate of approximately 5 wt % was achieved within 10 weeks at 25 °C and the degradation mechanism was investigated from both molecular and macroscopic levels. Therefore, this work provides a new type of partially biobased and degradable materials for substitution of traditional TPV

Reprocessable, Highly Transparent Ionic Conductive Elastomers Based on β‑Amino Ester Chemistry for Sensing Devices

Ionic conductive elastomers (ICEs) exhibit a compelling combination of ionic conductivity and elastic properties, rendering them excellent candidates for stretchable electronics, particularly in applications like sensing devices. Despite their appeal, a significant challenge lies in the reprocessing of ICEs without compromising their performance. To address this issue, we propose a strategy that leverages covalent adaptable networks (CANs) for the preparation of ICEs. Specifically, β-amino ester bonds as dynamic motifs are incorporated into a poly(ethylene oxide) network containing lithium bis(trifluoromethane) sulfonimide (LiTFSI) salt. LiTFSI-containing β-amino ester networks (LBAEs) exhibit superb transparency (94%), thermal stability (>280 °C), and modest conductivity (0.00576 mS·cm–1 at 20 °C), and some LBAEs maintain operational capability across a wide temperature range (−20 to 100 °C). By regulating the lithium salt content, the mechanical properties, conductivities, and viscoelastic behaviors can be tailored. Benefiting from these features, LBAEs have been successfully applied in sensing devices for monitoring human motion (e.g., finger bending, swallowing, and clenching). Notably, even after four reprocessing cycles, LBAEs demonstrate structural integrity and maintain their operational capability. This novel approach represents a promising solution to the reprocessing challenges associated with flexible conductive devices, demonstrating the successful integration of CANs and ICEs

Rapid Stereocomplexation between Enantiomeric Comb-Shaped Cellulose‑<i>g</i>‑poly(l‑lactide) Nanohybrids and Poly(d‑lactide) from the Melt

In this work we report the in situ preparation of fully biobased stereocomplex poly­(lactide) (SC-PLA) nanocomposites grafted onto nanocrystalline cellulose (NCC). The stereocomplexation rate by compounding high-molar-mass poly­(d-lactide) (PDLA) with comb-like NCC grafted poly­(l-lactide) is rather high in comparison with mixtures of PDLA and PLLA. The rapid stereocomplexation was evidenced by a high stereocomplexation temperature (<i>T</i>_c‑sc = 145 °C) and a high SC crystallinity (<i>X</i>_c‑sc = 38%) upon fast cooling (50 °C/min) from the melt (250 °C for 2 min), which are higher than currently reported values. Moreover, the half-life crystallization time (175–190 °C) of the SC-PLA was shortened by 84–92% in comparison with the PDLA/PLLA blends. The high­(er) stereocomplexation rate and the melt stability of the SC in the nanocomposites were ascribed to the nucleation effect of the chemically bonded NCC and the “memory effect” of molecular pairs in the stereocomplex melt because of the confined freedom of the grafted PLLA chains

Simultaneously Enhancing Mechanical Strength, Toughness, and Fire Retardancy of Biobased Polyurethane by Regulating Soft/Hard Segments and Crystallization Behavior

In this work, biobased flame-retardant polyurethanes were designed. First, a vanillin-based diol (VDP), as the hard segment, was prepared by condensation and addition reactions of vanillin with DDM (4,4′-diaminodiphenylmethane) and DOPO (9,10-dihydro-9-oxa-10-phospha­phenanthrene-10-oxide). Then, polyurethane materials FRBPU-xP were prepared by a polycondensation reaction of different contents of VDP, crystallized polycaprolactone diol, and HDI by modulating the amount (x) of P. Interestingly, when the amount of VDP was increased from 0 to 14.5 wt % (P = 1.0%) and the amount of PCL diol was decreased from 82.4 to 64.8 wt %, the Tg of the prepared FRBPU-xP was significantly increased from −34.7 to 2.8 °C, while the tensile strength increased from 10.7 to 15.6 MPa and the elongation at break increased from 822% to 930%, showing simultaneous mechanical strengthening and toughening. These behaviors can be ascribed to (1) the increase of the hard VDP diols and the enhancement of intermolecular interactions and (2) the decrease of the crystallinity from 21.2% to 14.5% due to the decreasing content of PCL diols and the inhibiting crystallization behavior induced by VDP, which helped to improve the ductility of the polyurethane material. Furthermore, the LOI value of FRBPU-0.5P reached 29.6%, and this material achieved a UL-94 V-0 rating. In addition, the polyurethanes showed good reprocessability, and FRBPU-1.0P had a retention of 72.6% and 93.3% for its tensile strength and elongation at break after thermal remolding, respectively. This work provides an idea for the preparation of high-performance biobased flame-retardant polyurethane

Simultaneously Enhancing Mechanical Strength, Toughness, and Fire Retardancy of Biobased Polyurethane by Regulating Soft/Hard Segments and Crystallization Behavior

In this work, biobased flame-retardant polyurethanes were designed. First, a vanillin-based diol (VDP), as the hard segment, was prepared by condensation and addition reactions of vanillin with DDM (4,4′-diaminodiphenylmethane) and DOPO (9,10-dihydro-9-oxa-10-phospha­phenanthrene-10-oxide). Then, polyurethane materials FRBPU-xP were prepared by a polycondensation reaction of different contents of VDP, crystallized polycaprolactone diol, and HDI by modulating the amount (x) of P. Interestingly, when the amount of VDP was increased from 0 to 14.5 wt % (P = 1.0%) and the amount of PCL diol was decreased from 82.4 to 64.8 wt %, the Tg of the prepared FRBPU-xP was significantly increased from −34.7 to 2.8 °C, while the tensile strength increased from 10.7 to 15.6 MPa and the elongation at break increased from 822% to 930%, showing simultaneous mechanical strengthening and toughening. These behaviors can be ascribed to (1) the increase of the hard VDP diols and the enhancement of intermolecular interactions and (2) the decrease of the crystallinity from 21.2% to 14.5% due to the decreasing content of PCL diols and the inhibiting crystallization behavior induced by VDP, which helped to improve the ductility of the polyurethane material. Furthermore, the LOI value of FRBPU-0.5P reached 29.6%, and this material achieved a UL-94 V-0 rating. In addition, the polyurethanes showed good reprocessability, and FRBPU-1.0P had a retention of 72.6% and 93.3% for its tensile strength and elongation at break after thermal remolding, respectively. This work provides an idea for the preparation of high-performance biobased flame-retardant polyurethane

Simultaneously Enhancing Mechanical Strength, Toughness, and Fire Retardancy of Biobased Polyurethane by Regulating Soft/Hard Segments and Crystallization Behavior

In this work, biobased flame-retardant polyurethanes were designed. First, a vanillin-based diol (VDP), as the hard segment, was prepared by condensation and addition reactions of vanillin with DDM (4,4′-diaminodiphenylmethane) and DOPO (9,10-dihydro-9-oxa-10-phospha­phenanthrene-10-oxide). Then, polyurethane materials FRBPU-xP were prepared by a polycondensation reaction of different contents of VDP, crystallized polycaprolactone diol, and HDI by modulating the amount (x) of P. Interestingly, when the amount of VDP was increased from 0 to 14.5 wt % (P = 1.0%) and the amount of PCL diol was decreased from 82.4 to 64.8 wt %, the Tg of the prepared FRBPU-xP was significantly increased from −34.7 to 2.8 °C, while the tensile strength increased from 10.7 to 15.6 MPa and the elongation at break increased from 822% to 930%, showing simultaneous mechanical strengthening and toughening. These behaviors can be ascribed to (1) the increase of the hard VDP diols and the enhancement of intermolecular interactions and (2) the decrease of the crystallinity from 21.2% to 14.5% due to the decreasing content of PCL diols and the inhibiting crystallization behavior induced by VDP, which helped to improve the ductility of the polyurethane material. Furthermore, the LOI value of FRBPU-0.5P reached 29.6%, and this material achieved a UL-94 V-0 rating. In addition, the polyurethanes showed good reprocessability, and FRBPU-1.0P had a retention of 72.6% and 93.3% for its tensile strength and elongation at break after thermal remolding, respectively. This work provides an idea for the preparation of high-performance biobased flame-retardant polyurethane

Simultaneously Enhancing Mechanical Strength, Toughness, and Fire Retardancy of Biobased Polyurethane by Regulating Soft/Hard Segments and Crystallization Behavior

In this work, biobased flame-retardant polyurethanes were designed. First, a vanillin-based diol (VDP), as the hard segment, was prepared by condensation and addition reactions of vanillin with DDM (4,4′-diaminodiphenylmethane) and DOPO (9,10-dihydro-9-oxa-10-phospha­phenanthrene-10-oxide). Then, polyurethane materials FRBPU-xP were prepared by a polycondensation reaction of different contents of VDP, crystallized polycaprolactone diol, and HDI by modulating the amount (x) of P. Interestingly, when the amount of VDP was increased from 0 to 14.5 wt % (P = 1.0%) and the amount of PCL diol was decreased from 82.4 to 64.8 wt %, the Tg of the prepared FRBPU-xP was significantly increased from −34.7 to 2.8 °C, while the tensile strength increased from 10.7 to 15.6 MPa and the elongation at break increased from 822% to 930%, showing simultaneous mechanical strengthening and toughening. These behaviors can be ascribed to (1) the increase of the hard VDP diols and the enhancement of intermolecular interactions and (2) the decrease of the crystallinity from 21.2% to 14.5% due to the decreasing content of PCL diols and the inhibiting crystallization behavior induced by VDP, which helped to improve the ductility of the polyurethane material. Furthermore, the LOI value of FRBPU-0.5P reached 29.6%, and this material achieved a UL-94 V-0 rating. In addition, the polyurethanes showed good reprocessability, and FRBPU-1.0P had a retention of 72.6% and 93.3% for its tensile strength and elongation at break after thermal remolding, respectively. This work provides an idea for the preparation of high-performance biobased flame-retardant polyurethane

Enhanced Thermal Stability and UV-Shielding Properties of Poly(vinyl alcohol) Based on Esculetin

In this article, PVA composites with outstanding thermal stability, UV shielding, and high transparency were fabricated on the basis of traditional Chinese medicine (esculetin). Characterization data have suggested in which the resulting PVA/esculetin (ESC) composites display excellent thermal stability compared to pure PVA and most of the PVA nanocomposites. The pyrolysis mechanism of PVA before and after modification with esculetin varies from chain unzipping degradation followed by chain random scission. The DPPH scavenging activity and FTIR measurements have illustrated that esculetin can scavenge reactive radicals, which leads to improvements in thermal stability and a change in the pyrolysis mechanism of PVA. More importantly, the resulting composites can almost completely block the whole UV region (200–400 nm) without any deterioration of the high transparency of the composites. Therefore, the composites can convert harmful UV light into blue light effectively, which is beneficial for their application as optical materials and devices

Simultaneously Enhancing Mechanical Strength, Toughness, and Fire Retardancy of Biobased Polyurethane by Regulating Soft/Hard Segments and Crystallization Behavior

In this work, biobased flame-retardant polyurethanes were designed. First, a vanillin-based diol (VDP), as the hard segment, was prepared by condensation and addition reactions of vanillin with DDM (4,4′-diaminodiphenylmethane) and DOPO (9,10-dihydro-9-oxa-10-phospha­phenanthrene-10-oxide). Then, polyurethane materials FRBPU-xP were prepared by a polycondensation reaction of different contents of VDP, crystallized polycaprolactone diol, and HDI by modulating the amount (x) of P. Interestingly, when the amount of VDP was increased from 0 to 14.5 wt % (P = 1.0%) and the amount of PCL diol was decreased from 82.4 to 64.8 wt %, the Tg of the prepared FRBPU-xP was significantly increased from −34.7 to 2.8 °C, while the tensile strength increased from 10.7 to 15.6 MPa and the elongation at break increased from 822% to 930%, showing simultaneous mechanical strengthening and toughening. These behaviors can be ascribed to (1) the increase of the hard VDP diols and the enhancement of intermolecular interactions and (2) the decrease of the crystallinity from 21.2% to 14.5% due to the decreasing content of PCL diols and the inhibiting crystallization behavior induced by VDP, which helped to improve the ductility of the polyurethane material. Furthermore, the LOI value of FRBPU-0.5P reached 29.6%, and this material achieved a UL-94 V-0 rating. In addition, the polyurethanes showed good reprocessability, and FRBPU-1.0P had a retention of 72.6% and 93.3% for its tensile strength and elongation at break after thermal remolding, respectively. This work provides an idea for the preparation of high-performance biobased flame-retardant polyurethane