High-Temperature Shape Memory Behavior of Semicrystalline Polyamide Thermosets

We have explored semicrystalline poly­(decamethylene terephthalamide) (PA 10T) based thermosets as single-component high-temperature (>200 °C) shape memory polymers (SMPs). The PA 10T thermosets were prepared from reactive thermoplastic precursors. Reactive phenylethynyl (PE) functionalities were either attached at the chain termini or placed as side groups along the polymer main chain. The shape fixation and recovery performance of the thermoset films were investigated using a rheometer in torsion mode. By controlling the <i>M</i>_n of the reactive oligomers, or the PE concentration of the PE side-group functionalized copolyamides, we were able to design dual-shape memory PA 10T thermosets with a broad recovery temperature range of 227–285 °C. The thermosets based on the 1000 g mol^–1 reactive PE precursor and the copolyamide with 15 mol % PE side groups show the highest fixation rate (99%) and recovery rate (≥90%). High temperature triple-shape memory behavior can be achieved as well when we use the melt transition (<i>T</i>_m ≥ 200 °C) and the glass transition (<i>T</i>_g = ∼125 °C) as the two switches. The recovery rate of the two recovery steps are highly dependent on the crystallinity of the thermosets and vary within a wide range of 74%–139% and 40–82% for the two steps, respectively. Reversible shape memory events could also be demonstrated when we perform a forward and backward deformation in a triple shape memory cycle. We also studied the angular recovery velocity as a function of temperature, which provides a thermokinematic picture of the shape recovery process and helps to program for desired shape memory behavior

Facilely Synthesizing Ethynyl Terminated All-Aromatic Liquid Crystalline Poly(esterimide)s with Good Processability and Thermal Resistance under Medium-Low Temperature via Direct Esterification

Developing a facile strategy to synthesize thermosetting all-aromatic liquid crystalline poly­(esterimide)­s (LCPEIs) at medium-low temperature and endowing LCPEIs with good processability and high thermal resistance are still two big challenges. Herein, a new solution polymerization based on direct esterification under 120 °C is developed, overcoming bottlenecks of traditional melt and solution polymerizations. Besides, two new reactive LCPEIs (LCPEI-1 and LCPEI-2) terminated with 3-ethynylaniline (3-EA) were synthesized, and their structures and properties were compared with two control samples without 3-EA end groups. LCPEI-1 and LCPEI-2 not only show good processing characteristics including low melting temperature (<i>T</i>_m = 200 °C), low melting viscosity, and good solubility in solvent, but their cured samples also have high glass transition temperature (<i>T</i>_g = 192 and 225 °C) and high storage modulus, whereas control samples, even treated with similar thermal history as curing procedure for LCPEI-1 and LCPEI-2, have poor performances. Cured-LCPEI-2 exhibits the highest <i>T</i>_g among polyesters with low <i>T</i>_m values (<250 °C) reported. The mechanism behind outstanding performances of LCPEIs is discussed

Water-Phase Synthesis of a Biobased Allyl Compound for Building UV-Curable Flexible Thiol–Ene Polymer Networks with High Mechanical Strength and Transparency

Using water as a reaction medium to synthesize biobased monomers with high renewable carbon content for preparing biobased polymers is of great importance for environmental protection and sustainable development. Herein, a trifunctional allyl compound, tris­(4-allyl-2-methoxyphenyl) phosphate (TAMPP) with 100% renewable carbon content was synthesized from renewable eugenol through one-step method using water as the solvent. TAMPP was then used to prepare flexible and transparent thiol–ene polymer networks TAMPP-SH via solvent-free thiol–ene “click” photopolymerization with various multifunctional thiols. The influences of the thiol functionality from 2 to 4 on structure and integrated performances were systematically researched. Among them, TAMPP-SH4 shows the best thermal and mechanical properties. Specifically, its glass transition temperature (<i>T</i>_g) is as high as 35 °C, while its tensile strength and modulus are as high as 19.8 ± 0.6 MPa and 601.6 ± 22.4 MPa, respectively. At the same time, it still maintains high flexibility. The nature behind these outstanding integrated performances is attributed to the unique structure of TAMPP, which is rich in aromatic structure, and the very high cross-linking density of TAMPP-SH4 network. The especially high renewable carbon content and outstanding thermal and mechanical performances clearly show that the TAMPP-SH4 network has great potential in fabricating flexible products

Biobased Heat Resistant Epoxy Resin with Extremely High Biomass Content from 2,5-Furandicarboxylic Acid and Eugenol

Preparing a biobased (biomass-based) high performance epoxy resin with extremely large biomass content is of great importance for sustainable development. Herein, a new epoxy resin with a precise structure, bis­(2-methoxy-4-(oxiran-2-ylmethyl)­phenyl)­furan-2,5-dicarboxylate (EUFU-EP), was synthesized from two biobased green and low toxic compounds (2,5-furandicarboxylic acid and eugenol) and the biomass content of EUFU-EP is as large as 93.3%. In addition, a new biobased epoxy resin, EUFU-EP/MHHPA, was prepared by using methyl hexahydrophthalic anhydride (MHHPA) as the curing agent and 2-ethyl-4-methylimidazole as the curing accelerator. The curing reactivity and integrated performances including thermal and mechanical properties as well as flame retardancy of the cured resin were systematically researched and compared with those of petrochemical resource-based epoxy resin (DGEBA/MHHPA) consisting of commercial diglycidyl ether of bisphenol A (DGEBA), MHHPA and 2-ethyl-4-methylimidazole. Results show that EUFU-EP/MHHPA and DGEBA/MHHPA have similar curing reactivity, but cured EUFU-EP/MHHPA resin shows better thermal properties, rigidity, and flame retardancy than cured DGEBA/MHHPA resin. Specifically, the glass transition temperature (<i>T</i>_g) of EUFU-EP/MHHPA resin is as high as 153.4 °C, the storage modulus at 50 °C increases by 19.8%; meanwhile, both peak heat release rate and total heat release reduce by 19.0%. The nature behind these outstanding integrated performances is attributed to the unique structure of EUFU-EP, which is not only rich in aromatic structure but also has a furan ring. The especially large biomass content and outstanding thermal, mechanical, and flame retarding performances clearly show that EUFU-EP resin has a great potential in actual applications

Selective and Controlled Release Responsive Nanoparticles with Adsorption-Pairing Synergy for Anthocyanin Extraction

Anthocyanins with different structures have different anti-inflammatory and anti-cancer properties. Precise structural use can improve the chemopreventive effects of anthocyanins and enhance treatment outcomes because the anthocyanin structure influences its functional sites and activities. However, owing to the available variety of anthocyanins and their complex structures, the low matching of intermolecular forces between existing adsorbents and anthocyanins limits the targeted separation of anthocyanin monomers. Short-range and efficient selective binding, which is difficult to achieve, is the current focus in the extraction field. We here developed self-assembled Fe3O4-based nano adsorbers with different surface modifications based on adsorption-pairing synergy. The electrostatic force, coordination bond, hydrogen bond, and π–π* bond together induced selective adsorption between Fe3O4 nanoparticles and anthocyanin molecules. An acid-release solution disrupted the polarity balance in the aforementioned association system, thereby promoting the controlled release of anthocyanins. Among the candidates, the effects of morphology, particle size, surface charge, and functional group on adsorption performance were analyzed. The polyacrylamide-modified magnetic Fe3O4 nanoparticles were found to be favorable for selectively extracting anthocyanin, with an adsorption capacity of 19.74 ± 0.07 mg g–1. The release percentage of cyanidin-3-O-glucoside reached up to 98.6% ± 1.4%. This study offers a scientific basis for developing feasible nanotechniques to extract anthocyanins and plant active substances

Selective and Controlled Release Responsive Nanoparticles with Adsorption-Pairing Synergy for Anthocyanin Extraction

Anthocyanins with different structures have different anti-inflammatory and anti-cancer properties. Precise structural use can improve the chemopreventive effects of anthocyanins and enhance treatment outcomes because the anthocyanin structure influences its functional sites and activities. However, owing to the available variety of anthocyanins and their complex structures, the low matching of intermolecular forces between existing adsorbents and anthocyanins limits the targeted separation of anthocyanin monomers. Short-range and efficient selective binding, which is difficult to achieve, is the current focus in the extraction field. We here developed self-assembled Fe3O4-based nano adsorbers with different surface modifications based on adsorption-pairing synergy. The electrostatic force, coordination bond, hydrogen bond, and π–π* bond together induced selective adsorption between Fe3O4 nanoparticles and anthocyanin molecules. An acid-release solution disrupted the polarity balance in the aforementioned association system, thereby promoting the controlled release of anthocyanins. Among the candidates, the effects of morphology, particle size, surface charge, and functional group on adsorption performance were analyzed. The polyacrylamide-modified magnetic Fe3O4 nanoparticles were found to be favorable for selectively extracting anthocyanin, with an adsorption capacity of 19.74 ± 0.07 mg g–1. The release percentage of cyanidin-3-O-glucoside reached up to 98.6% ± 1.4%. This study offers a scientific basis for developing feasible nanotechniques to extract anthocyanins and plant active substances

Chemistry and Rheological Behavior of Cross-Linked Liquid Crystal Polyarylate with a Mixed End-Capping Strategy

Liquid crystal thermosets (LCTs) terminated with a phenylethynyl group (PEPA) have attracted extensive attention because their tunable processability is superior to thermoplastic liquid crystal polyarylates (LCPs). However, the high curing temperature and low curing rate of PEPA restrict regulation on the performance of cured LCTs. To address above challenges, the bis- or mixed end-cappers with inner and outer ethynyl groups were utilized to terminate LCP. The curing temperature was decreased from 370 to 320 °C by introducing high reactive 3-ethynylaniline (EA) and derivatives as end-cappers. Meanwhile, the cured LCT exhibited a high storage modulus (∼30 MPa) at a rubbery plateau (400 °C) due to a highly cross-linked network (cross-linking density = 3131.9 mol·m–3). Moreover, appropriate mixed end groups could realize a similar curing rate (∼500 Pa·s·min–1) to their highly reactive counterparts. Consequently, rheological measurements were innovatively conducted to understand the curing mechanism of diverse end cappers, which would inspire new strategies to develop high-performance thermosets

Light-Controlled Triple-Shape-Memory, High-Permittivity Dynamic Elastomer for Wearable Multifunctional Information Encoding Devices

Self-powered information encoding devices (IEDs) have drawn considerable interest owing to their capability to process information without batteries. Next-generation IEDs should be reprogrammable, self-healing, and wearable to satisfy the emerging requirements for multifunctional IEDs; however, such devices have not been demonstrated. Herein, an integrated triboelectric nanogenerator-based IED with the aforementioned features was developed based on the designed light-responsive high-permittivity poly(sebacoyl diglyceride-co-4,4′-azodibenzoyl diglyceride) elastomer (PSeDAE) with a triple-shape-memory effect. The electrical memory feature was achieved through a microscale shape-memory property, enabling spatiotemporal information reprogramming for the IED. Macroscale shape-memory behavior afforded the IED shape-reprogramming ability, yielding wearable and detachable features. The dynamic transesterifications and light-heating groups in the PSeDAE afforded a remotely controlled rearrangement of its cross-linking network, producing the self-healing IED

Light-Controlled Triple-Shape-Memory, High-Permittivity Dynamic Elastomer for Wearable Multifunctional Information Encoding Devices

Self-powered information encoding devices (IEDs) have drawn considerable interest owing to their capability to process information without batteries. Next-generation IEDs should be reprogrammable, self-healing, and wearable to satisfy the emerging requirements for multifunctional IEDs; however, such devices have not been demonstrated. Herein, an integrated triboelectric nanogenerator-based IED with the aforementioned features was developed based on the designed light-responsive high-permittivity poly(sebacoyl diglyceride-co-4,4′-azodibenzoyl diglyceride) elastomer (PSeDAE) with a triple-shape-memory effect. The electrical memory feature was achieved through a microscale shape-memory property, enabling spatiotemporal information reprogramming for the IED. Macroscale shape-memory behavior afforded the IED shape-reprogramming ability, yielding wearable and detachable features. The dynamic transesterifications and light-heating groups in the PSeDAE afforded a remotely controlled rearrangement of its cross-linking network, producing the self-healing IED