Semicrystalline State Research Articles

Poisson’s ratio transition in strain crystallizing elastomer: from rubbery amorphous to semicrystalline

AbstractThe Poisson’s ratio (μ) of natural rubber (NR) undergoing strain-induced crystallization (SIC) during uniaxial stretching was investigated as a function of the applied stretch ($${\lambda }_{{||}}$$ λ ∣ ∣ ) over a broad $${\lambda }_{{||}}$$ λ ∣ ∣ range, encompassing the SIC onset stretch ($${{\lambda }_{{||}}}^{* }$$ λ ∣ ∣ * ≈ 4.1). Below $${{\lambda }_{{||}}}^{* }$$ λ ∣ ∣ * , μ remains near 1/2, indicating the incompressible behavior of NR in its fully rubbery amorphous state. However, once $${\lambda }_{{||}}$$ λ ∣ ∣ exceeds $${{\lambda }_{{||}}}^{* }$$ λ ∣ ∣ * , μ decreases as the degree of crystallinity (χc) increases. As $${\lambda }_{{||}}$$ λ ∣ ∣ increases from $${{\lambda }_{{||}}}^{* }$$ λ ∣ ∣ * to fracture stretch ($${\lambda }_{{||}}$$ λ ∣ ∣ ≈ 7.1), χc increases to 18%, and μ gradually decreases to 0.33. This reduction in μ reflects the transformation of the NR matrix from a rubbery amorphous state to a semicrystalline state. In fact, the true stress (force per cross-sectional area in the deformed state) at the fracture point, obtained via actual lateral contraction, is approximately 85% of that estimated under the assumption μ = 1/2. These findings provide a critical foundation for accurately modeling the mechanical behavior of strain-crystallizing elastomers.

Diimide-Mediated Hydrogenation of Nitrile Butadiene Rubber

The hydrogenation of nitrile butadiene rubber (NBR) has shown great potential for improving its physical, thermal, mechanical, and chemical stability. Hydrogenation process of NBR in this work involved the utilization of diimide produced from the interaction between hydrazine hydrate (N2H4) and hydrogen peroxide (H2O2), with the addition of boric acid as a promoter. Attenuated total reflectance Fourier transform infrared (ATR-FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and X-ray diffraction (XRD) were used to evaluate the degree of hydrogenation, glass transition, thermal stability, and rubber crystallinity, respectively. The highest hydrogenation degree was 99%, which resulted in a 57% gel content. Upon hydrogenation, both the glass transition temperature (Tg) and decomposition temperature (Td) increased. The hydrogenated rubber samples generally showed an amorphous state, except for the 99% hydrogenated sample, which displayed a semi-crystalline state. However, using diimide for direct hydrogenation yields a side reaction from the free radicals in the system, which leads to gel formation. Optimization was accomplished by employing the response surface methodology (RSM), which entailed manipulating parameters such as the total solid content (TSC) of NBR, reaction time, and the mole ratio of H2O2 to N2H4, to reduce the percentage of gel content. The RSM analysis identified the optimum reaction conditions as a 1:1 mole ratio of H2O2: N2H4 and 25% TSC, with a reaction time of 8 h, which yielded 32% gel content percentage, where a mole ratio of H2O2 to N2H4 and reaction time indicated a synergistic effect, whereas TSC denoted an antagonistic effect.

Characterization and modeling of laser transmission welded polyetherketoneketone (PEKK) joints: Influence of process parameters and annealing on weld properties

Welding high-performance thermoplastics has gained popularity across various industries such as automotive, aerospace, and medical. Laser transmission welding (LTW) has emerged as an effective method for joining thermoplastic parts due to its precise control and high joint quality. PAEK (polyaryletherketone) are wide spreading over various industrial applications as a substitute to metals and thermosets when high durability and performance are required. Polyetherketoneketone (PEKK) is one of these PAEK and it has received less attention than PEEK until now. PEKK, being a semi-crystalline thermoplastic, requires additional care during processing due to its propensity to crystallize. This study presents both experimental and numerical investigations into LTW of PEKK molded parts, aiming to understand the influence of welding parameters and crystallinity on weld joint morphology and mechanical properties. PEKK plates, prepared in amorphous and semi-crystalline states, are subjected to LTW using a 975 nm diode laser. Material characterization confirms differences in crystallinity between the samples, which affect their thermal and optical properties, which are crucial for welding. Welding tests are conducted with varying laser power (between 75 and 95 W) and semi-transparent part thickness (2 and 4 mm). The morphology of joints is analysed. Assemblies undergo post-weld annealing treatment to examine its influence on weld crystallinity and consequent mechanical properties. Results reveal an anisotropic distribution of crystallinity within the heat-affected zone (HAZ). The depths of the molten layer (ML) and semi-crystalline layer (scL) vary with laser power and assembly type. A notable decrease in weld strength with laser power is highlighted, while annealing leads to enhanced crystallinity and improved weld strength. Despite variations, high weld strengths are achieved with annealing. Computational modelling elucidates the complex interplay between laser irradiation, temperature distribution, and crystallization kinetics observed experimentally. Overall, this comprehensive investigation provides valuable insights into optimizing LTW parameters for PEKK parts.

Structure-properties relationships in new polymer nanocomposites based on the renewable poly(butylene succinate) filled with low amounts of nanoparticles of 1-3D geometries

A series of polymer nanocomposites (PNCs) based on the renewable poly(butylene-succinate) (PBSu) reinforced with 1 wt% of different nanoparticles (NP), namely, silica (SiO2), montmorillonite (MMT), graphene oxide (GO) and carbon nanotubes (CNT), were synthesized and studied herein. The investigation focuses on both the direct and indirect NP effects on the interfacial interactions, thermal transitions, crystallinity, electrical and thermal conductivity, mechanical properties and molecular dynamics. For that, a sum of complementary techniques was employed, regarding both the structure and performance. The clearly direct effect is related to the promotion of crystal nucleation at the presence of both particles, related to the fillers’ dimensionality (aspect ratio) and the non-worth noting interfacial interactions. The degree of crystallinity of PBSu mildly increases, whereas the semicrystalline morphology (sizes, numbers, distributions of the crystals) is systematically denser in the PNCs. In agreement with previous findings on PBSu, the polymer cannot be preserved amorphous, at least by conventional methods. Consequently, the macroscopic properties, namely, the thermal diffusivity/conductivity as well as the mechanical performance were found connected to crystallinity, in particular, to the semicrystalline morphology (indirect filler effect). PBSu/CNT was surprisingly found electrically conductive, despite the low CNT loading, whereas the rest of the samples are insulating. The molecular dynamics map was constructed here for the first time, obviously only for the semicrystalline state. The cooperativity of PBSu chains drops in the PNCs, most probably, affected by the dense semicrystalline structures that seem to impose an increase in the free volume of the amorphous polymer fraction. Overall, the PBSu PNCs were found to offer potentials for wide range manipulation of properties, via relatively mild processing (synthesis, thermal treatments).

Encapsulation of Zataria multiflora essential oil in electrosprayed zein microcapsules: Characterization and antimicrobial properties

This research was carried out to make zein microcapsules containing Zataria multiflora essential oil (Z. multiflora EO) by the electrospraying method to evaluate the antimicrobial properties of the microcapsules on Z. tritici and F. graminearum fungi, as well as X. translucens and R. tritici bacteria. To achieve this aim, Z. multiflora EO was encapsulated at different concentrations (0, 5,10%, and 15% v/v) in electrosprayed zein microcapsules and the characteristics of the electrosprayed zein microcapsules were examined using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), X-ray diffraction (XRD), and Fourier transform infrared (FTIR). Porosity and specific surface values were measured by the BET method. Then, the amount of loaded Z. multiflora EO was determined for efficiency. The antifungal and antibacterial activities of the electrosprayed zein microcapsules were measured using the agar well diffusion method. The results of SEM showed that the morphology of the electrosprayed zein microcapsule was influenced by the concentration of Z. multiflora EO (p < 0.05). DSC results indicated the compatibility between the Z. multiflora EO and the zein polymer. The FTIR spectrum showed that adding Z. multiflora EO changed the secondary structure of the zein protein. XRD patterns showed that the electrosprayed zein microcapsules were in a semi-crystalline state. The BET results determined the average pore diameter of microcapsules. Electrosprayed zein microcapsules containing Z. multiflora EO had inhibitory effects on both fungi and bacteria (p < 0.05). According to the results, the electrosprayed zein microcapsules containing Z. multiflora EO can be used as an antimicrobial compound for fruit and vegetable products.

Enhancing Oral Bioavailability and Brain Biodistribution of Perillyl Alcohol Using Nanostructured Lipid Carriers.

Perillyl alcohol (POH), a bioactive monoterpenoid derived from limonene, shows promise as an antitumor agent for brain tumor treatment. However, its limited oral bioavailability and inadequate brain distribution hinder its efficacy. To address these challenges, this study developed nanostructured lipid carriers (NLCs) loaded with POH to improve its brain biodistribution. The NLCs prepared using hot homogenization exhibited an average diameter of 287 nm and a spherical morphology with a polydispersity index of 0.143. High encapsulation efficiency of 99.68% was achieved. X-ray diffraction analyses confirmed the semicrystalline state of POH-loaded NLCs. In vitro release studies demonstrated a biphasic release profile. Stability studies in simulated gastric and intestinal fluids confirmed their ability to withstand pH variations and digestive enzymes. In vivo pharmacokinetic studies in rats revealed significantly enhanced oral bioavailability of POH when encapsulated in the NLCs. Biodistribution studies showed increased POH concentration in brain tissue with NLCs compared with free POH, which was distributed more in non-target tissues such as the liver, lungs, kidneys, and spleen. These findings underscore the potential of NLCs as effective delivery systems for enhancing oral bioavailability and brain biodistribution of POH, providing a potential therapeutic strategy for brain tumor treatment.

The Role of Polymer Chain Stiffness and Guest Nanoparticle Loading in Improving the Glass Transition Temperature of Polymer Nanocomposites.

The impact of polymer chain stiffness characterized by the bending modulus (kθ) on the glass transition temperature (Tg) of pure polymer systems, as well as polymer nanocomposites (PNCs), is investigated using molecular dynamics simulations. At small kθ values, the pure polymer system and respective PNCs are in an amorphous state, whereas at large kθ values, both systems are in a semicrystalline state with a glass transition at low temperature. For the pure polymer system, Tg initially increases with kθ and does not change obviously at large kθ. However, the Tg of PNCs shows interesting behaviors with the increasing volume fraction of nanoparticles (fNP) at different kθ values. Tg tends to increase with fNP at small kθ, whereas it becomes suppressed at large kθ.

Effect of Monomer Type on the Synthesis and Properties of Poly(Ethylene Furanoate).

This work aimed to produce bio-based poly(ethylene furanoate) (PEF) with a high molecular weight using 2,5-furan dicarboxylic acid (FDCA) or its derivative dimethyl 2,5-furan dicarboxylate (DMFD), targeting food packaging applications. The effect of monomer type, molar ratios, catalyst, polycondensation time, and temperature on synthesized samples' intrinsic viscosities and color intensity was evaluated. It was found that FDCA is more effective than DMFD in producing PEF with higher molecular weight. A sum of complementary techniques was employed to study the structure-properties relationships of the prepared PEF samples, both in amorphous and semicrystalline states. The amorphous samples exhibited an increase in glass transition temperature of 82-87 °C, and annealed samples displayed a decrease in crystallinity with increasing intrinsic viscosity, as analyzed by differential scanning calorimetry and X-ray diffraction. Dielectric spectroscopy showed moderate local and segmental dynamics and high ionic conductivity for the 2,5-FDCA-based samples. The spherulite size and nuclei density of samples improved with increased melt crystallization and viscosity, respectively. The hydrophilicity and oxygen permeability of the samples were reduced with increased rigidity and molecular weight. The nanoindentation test showed that the hardness and elastic modulus of amorphous and annealed samples is higher at low viscosities due to high intermolecular interactions and degree of crystallinity.

Construction of novel Cu-α-diimide interactions for enhancing thermal resistance and dimensional stability of polyimide films

The new-generation polyimide films with simultaneously outstanding thermal stability and low coefficient of linear thermal expansion (CTE) are urgently needed. Herein, coordination bonds were employed to improve polyimide films' heat resistance and dimensional stability. Polyimide-Cu complex films were fabricated by incorporating α-diimide units (bidentate ligands) into the BPDA-ODA (the structure of commercially available Upilex-R® polyimide films) backbones. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and Energy dispersive X-ray mapping results showed that the coordination interactions occur between α-diimide and copper ions. Wide-angle X-ray diffraction (WAXD) and two-dimensional small-angle X-ray scattering (SAXS) spectra demonstrated that Cu-α-diimide coordination structures introduced in intermolecular chains leading polyimide films transformed from a semi-crystalline state to amorphous state, and inhibited the long-period formation structures. The plateau modulus and longer characteristic relaxation time (τ∗ = 1996.5 s) revealed by dynamic thermomechanical analysis indicated that crosslink networks were successfully formed by constructing coordination bonds. As a result, polyimide films' thermal resistance and dimensional stability were simultaneously enhanced. The typical PI-Cu50 films exhibited elevated glass transition temperatures of 353 °C (pristine PI-Cu0 ∼ 302 °C) and a lower CTE of 47.4 ppm/K (pristine PI-Cu0 films ∼ 64.4 ppm/K) in ranges of 300–400 °C, showing a promising application in the field of high-temperature environments.

Endowing Polythioester Vitrimer with Intrinsic Crystallinity and Chemical Recyclability.

Technologically important thermosets face a long-standing end-of-life (EoL) problem of non-reprocessability, a more sustainable solution of which has resolved to nascent vitrimers that can merge the robust material properties of thermosets and the reprocessability of thermoplastics. However, the lifecycle of vitrimers is still finite, as they often suffer from significant deterioration of mechanical performance following multiple reprocessing cycles, analogous to mechanical recycling, and they often show undesired creep under working conditions. To address these two key limitations, we have developed a cross-linked semi-crystalline polythioester with both dynamic covalent bonds and intrinsic crystallinity and chemical recyclability, affording a vitrimeric system that exhibits not only reprocessability and crystallinity-restricted creep but also complete chemical recyclability to initial monomer by catalyzed depolymerization in solution or bulk. Therefore, reported herein is an "infinite" vitrimer system that is empowered with a facile closed-loop EoL option once serial reprocessing deteriorates performance and the material can no longer meet the application requirements. Specifically, the polythioester vitrimer was constructed by copolymerization of a bicyclic thioester with a bis-dithiolane, producing dynamically cross-linked polythioesters with excellent property tunability, from amorphous to semi-crystalline states and melting transition temperatures from 91 to 178 °C.

DNA folding by protamine from loops to stacks.

In sperm, DNA undergoes a dramatic reorganization to a semi-crystalline state. This incredible compaction is the work of positively charged protamine proteins which bend and loop negatively charged DNA into a series of toroids. Interestingly, other positively charged molecules such as spermine or cations such as cobalt (+3) have been shown to form these toroid structures in vitro, indicating that the physics that drives this process is likely to be electrostatic. Still, the exact mechanism and the states in the folding pathway are unknown. We have previously shown that multiple protamine molecules “bind and bend” the DNA into a loop. But, what happens after loop formation? To answer this question, we measured folding by protamine in vitro on DNA molecules (length = 600-3000 bp) that are known to form several loops. Using atomic force microscopy (AFM), we were able to identify several intermediate folded structures: molecules with a single loop (a loop), molecules with two or more loops that were connected at a single location like a flower (flowers), and molecules with two or more loops stacked on top of one another (stacks). Using a tethered particle motion (TPM) assay we measured real-time folding of the DNA into these structures. At low protamine concentrations (0.1 µM), we observed many, long-lived, discrete folded states indicative of protamine bending, but at higher concentrations (>0.1 µM) these states appeared as a single, initial folding event. We hypothesize that this single, initial folding event is protamine bending the DNA all along its length, causing multiple loops. These loops then collapse into a stack. More work is necessary to determine how these stacks eventually form toroids. This work is important for spermiogenesis and DNA condensation, but also may useful in DNA nanoengineering.

An Equilibrium State Diagram for Storage Stability and Conservation of Active Ingredients in a Functional Food Based on Polysaccharides Blends.

A functional food as a matrix based on a blend of carbohydrate polymers (25% maltodextrin and 75% inulin) with quercetin and Bacillus claussi to supply antioxidant and probiotic properties was prepared by spray drying. The powders were characterized physiochemically, including by moisture adsorption isotherms, X-ray diffraction (XRD), scanning electron microscopy (SEM), and modulated differential scanning calorimetry (MDSC). The type III adsorption isotherm developed at 35 °C presented a monolayer content of 2.79 g of water for every 100 g of dry sample. The microstructure determined by XRD presented three regions identified as amorphous, semicrystalline, and crystalline-rubbery states. SEM micrographs showed variations in the morphology according to the microstructural regions as (i) spherical particles with smooth surfaces, (ii) a mixture of spherical particles and irregular particles with heterogeneous surfaces, and (iii) agglomerated irregular-shape particles. The blend's functional performance demonstrated antioxidant activities of approximately 50% of DPPH scavenging capacity and viability values of 6.5 Log10 CFU/g. These results demonstrated that the blend displayed functional food behavior over the complete interval of water activities. The equilibrium state diagram was significant for identifying the storage conditions that promote the preservation of functional food properties and those where the collapse of the microstructure occurs.

Thermal Conduction and Phonon Transport in Folded Polyethylene Chains

Using theory and simulations, we have investigated the phonons and their role in thermal energy transport in semicrystalline polyethylenes. Considering alternating stacks of lamellae and amorphous regions, and labeling one polyethylene chain interwoven among two amorphous regions and one lamella, we have explored the underlying mechanism of thermal conductivity of polyethylene in its semicrystalline state. We report that hairpin-like folds at the crystalline–amorphous interface significantly scatter phonons, allowing only less than half of the phonons to transmit through polyethylene backbone. Monitoring the phonon propagation and scattering at the interfaces, we have computed thermal conductivity of semicrystalline polyethylene. We have derived a design principle to control thermal conductivity of semicrystalline polyethylene in terms of lamellar thickness and the number of folds per chain at the crystalline–amorphous interface.

Optimising Starch Transformation in Aquafeed Extrusion for Enhanced Water Stability and Performance

The physical quality of aquafeed pellets is paramount for the health and performance of aquatic species in aquaculture systems. Starch, a small, but necessary component of aquafeed, plays a crucial role in creating durable and water-stable pellets. This paper investigates the complex relationship between starch transformation during extrusion cooking and its influence on water stability. Through a series of experiments involving various extrusion parameters, including three melt moisture levels and three screw speeds, the study reveals that the key to producing water-stable aquafeed lies in optimizing starch gelatinization and minimizing dextrinization. High screw speeds, in conjunction with moderate to high melt moisture levels, facilitate starch gelatinization while avoiding dextrinization, resulting in pellets with superior water stability. Conversely, low melt moisture levels at any screw speed or any melt moisture at low screw speeds lead to poor water stability due to increased dextrinization or suboptimal gelatinization levels. The research also underscores the critical role of the glass transition of starch. Starch in its semi-crystalline state is found to be more susceptible to shear degradation during extrusion. Therefore, rapidly elevating the raw material's temperature above its glass transition temperature is crucial for achieving water-stable aquafeed.

Effects of branching and polydispersity on thermal conductivity of paraffin waxes

• Increased branching of paraffin molecules leads to decreased thermal conductivity. • Polydispersity has a minor effect on thermal conductivity at 250 K, but none at 450 K. • For branched paraffin, there is a strong concomitance of crystallinity and thermal conductivity. • Increased thermal conductivity of polydisperse paraffin is explained purely by increasing average chain length. Paraffin waxes are promising phase change materials, abundantly available at very low cost. Having large latent heat, these materials can be used for thermal energy storage. However, when used in heat batteries, paraffin’s low thermal conductivity prevents fast charging and discharging. This calls for the design of tailored hybrid materials with improved properties, the present study concentrates on properties of pure paraffin wax. Using fully atomistic molecular-dynamics (MD) simulations, we study the effects of polydispersity and branching on the thermal conductivity of paraffin waxes, in molten (450 K) and solid (250 K) state. Both branching and polydispersity affect the density and especially the crystallinity of the solid. Branching has a pronounced effect on crystallisation caused by inhibited alignment of the polymer backbones while the effect of polydispersity is less pronounced. The thermal conductivity (TC) has been simulated using the reverse non-equilibrium molecular-dynamics method, as well as the equilibrium Green-Kubo approach. Increased branching, added to backbones comprised of twenty monomers, results in decreasing TC of up to 30%, polydispersity only has an effect in the semi-crystalline state. Comparison to available experiments shows good agreement which validates the model details, applied force field and the calculation methods. We show that at comparable computational costs, the reverse non-equilibrium MD approach produces more reliable results for TC, as compared to the equilibrium Green-Kubo method. The major contribution to TC by acoustic phonon transport along the backbone was shown by analysing extreme cases. The phonon density of states (PDOS) of samples with high branching or with small chain length displayed diminished peaks in the acoustic range as compared to the PDOS of samples with low branching or larger chain length, respectively. The suggested MD approach can definitely be used to investigate specific material modifications aimed at increasing the overall TC.

Sulfolane Crystal Templating: A One-Step and Tunable Polarity Approach for Self-Assembled Super-Macroporous Hydrophobic Monoliths.

Freeze-casting (ice templating) is generally used to prepare super-macroporous materials. However, water solubility limits the application of freeze-casting in hydrophobic material fabrication. In the present work, inexpensive and low-toxic sulfolane was used as a novel crystallization-induced porogen (sulfolane crystal templating) to prepare super-macroporous hydrophobic monoliths (cryogels) with tunable polarity. The phase transition of sulfolane consisted of reversible processes in the liquid, semi-crystalline, and crystalline states. Because of the density change during phase transition, liquid sulfolane experienced a 16.4% volume shrinkage per unit mass. Thus, the cryogels obtained using the conventional freezing method contained obvious hollow-shaped defects. Furthermore, a novel route of pre-cooling, pre-crystallization, crystal growth, freezing, and thawing (PPCFT) was employed to prepare cryogels with defect-free macroscopic morphology and uniform pore structure. The as-obtained cryogels were composed of a super-macroporous structures and interconnected channels, and their porosity ranged between 85 and 97%. Moreover, the cryogels manifested good hydrophobicity (contact angle = 120-130°) and had absorption capacities greater than 10 g g-1 for oils and organic liquids. The maximum absorption capacities of the resultant cryogels in dichloromethane, ethyl acetate, and liquid paraffin were 60.3, 35.8, and 15.2 g g-1, respectively. Moreover, sulfolane could conveniently dissolve hydrophobic and hydrophilic monomers to generate amphiphilic cryogels (contact angle = 130-0°). Therefore, sulfolane crystal templating is a potential fabrication method for super-macroporous hydrophobic materials with tunable polarity.

Bottlebrush Elastomers with Crystallizable Side Chains: Monitoring Configuration of Polymer Backbones in the Amorphous Regions during Crystallization.

Brush-like elastomers with crystallizable side chains hold promise for biomedical applications requiring the presence of two distinct mechanical states below and above body temperature: hard and supersoft. The hard semicrystalline state facilitates piercing of the body whereupon the material softens to match the mechanics of surrounding soft tissue. To understand the transition between the two states, the crystallization process was studied with synchrotron X-ray scattering for a series of brush elastomers with poly(ε-caprolactone) side chains bearing from 7 to 13 repeat units. The so-called bottlebrush correlation peak was used to monitor configuration of bottlebrush backbones in the amorphous regions during the crystallization process. In the course of crystallization, the backbones are expelled into the interlamellar amorphous gaps, which is accompanied by their conformational changes and leads to partitioning to unconfined (melt) and confined (semicrystalline) (conformational) states. The crystallization process starts by consumption of the unconfined macromolecules by the growing crystals followed by reconfiguration of macromolecules within the already grown spherulites.

Long-term in vivo degradation behavior of poly(trimethylene carbonate-co-2, 2′-dimethyltrimethylene carbonate)

Poly(trimethylene carbonate-co-2, 2′-dimethyltrimethylene carbonate) P(TMC-co-DTC) copolymers with different molecular weights or molar ratios were prepared by bulk ring-opening polymerization (ROP) of trimethylene carbonate (TMC) and 2, 2′-dimethyltrimethylene carbonate (DTC). The in vivo degradation behavior of the resulting copolymers of 2 mm diameter was subsequently investigated by implanting the samples subcutaneously in the back of rats. The data showed that the sample's mass loss was reduced, and the form-stability was enhanced with the increase of DTC segments content in the copolymer while increasing the molecular weight could accelerate the degradation rate and improve the form-stability of the copolymers. Among them, the samples containing 25 mol% DTC segments with a molecular weight of 205 kDa achieved the highest mass loss of 26.1% and maintained good form-stability after 35 weeks of implantation. In particular, implants with high DTC segments amount of 75 mol% (molecular weight of 208 kDa) maintained excellent form-stability and a low mass loss of 4.8% during the implantation cycle and exhibited some properties different from the other groups. Further experimental results showed that the content of DTC segments increased from 74.4% to 77.3%, and the crystallinity of the copolymer transformed to semi-crystalline state also increased from 61.4% to 76.4% during the degradation. The Tg, Tm and hardness of the degraded polymers were correspondingly improved. In addition, the degradation mechanism of surface erosion in vivo of the resulting P(TMC-co-DTC) copolymers were verified. This work provides a promising class of candidate carrier materials for the application of long-acting drug delivery systems through a detailed study of the in vivo degradation behavior of P(TMC-co-DTC) copolymers.

Fullerenes Materials Contribute to Ordered Interfacial Cell Water Improving Cellular Electrodynamics and Oxidative Stress Management

The role of water in living systems is complex and a primary mediator of localized and long‐range biological effects in the cell. Of the approximately 70% of cell water, 20‐30% forms a structured semi‐crystalline gel state of water layers, where it also hydrates surfaces of biomolecules and cell structures and is essential for life. Decreases in ordered interfacial water are associated with cellular dysfunction and disease. This interfacial water behaves quantumly. The customary Coulomb Law of electrostatics does not apply, allowing the accumulation of tissues composed of negatively charged cell bodies. Interfacial water is responsible for the thermodynamics of proton and electron transfer and long‐range quantum electrodynamic coherence coordinating quantum criticality of the cellular machinery and systemic integration necessary of complex organisms. We propose that fullerene material increases interfacial water ordering, beneficially altering its electromagnetic properties. Fullerene materials can bind with cellular structures and protein secondary structures not typically available for water interaction, through weak van der Waals forces or pi‐pi stacking arrangements containing aromatic rings with dense pi electron clouds and hydrophobic functional groups. Modulating partial charges, dipoles, and quadrupoles in fullerene materials that result from coherent microtubule‐generated electromagnetic fields helps enhance and extend long‐range ordered water layers and electrostatics between hydrophobic molecules thought necessary for the self‐assembly of bio‐macromolecules. We propose that fullerenes short and long‐range enhancement of structured interfacial water contributes to many of the observed effects of fullerenes in vivo, including a non‐stoichiometric redox mechanism for the well‐established antioxidant activity of fullerene materials.

Modulation of Interfacial Adhesion Using Semicrystalline Shape-Memory Polymers.

Semicrystalline shape-memory elastomers are molded into deformable geometrical features to control adhesive interactions between elastomers and a glass substrate. By mechanically and thermally controlling the deformation and phase-behavior of molded features, we can control the interfacial contact area and the interfacial adhesive force. Results indicate that elastic energy is stored in the semicrystalline state of deformed features and can be released to break attractive interfacial forces, automatically separating the glass substrate from the elastomer. Our findings suggest that the shape-memory elastomers can be applied in various contact printing applications to control adhesive forces and delamination mechanics during ink pickup and transfer.