Bond Content Research Articles

Branched Oligomer-Based Reversible Adhesives Enabled by Controllable Self-Aggregation.

Supramolecular adhesion material systems based on small molecules have shown great potential to unite the great contradiction between strong adhesion and reversibility. However, these material systems suffer from low adhesion strength/narrow adhesion span, limited designability, and single interaction due to fewer covalent bond content and action sites in small molecules. Herein, an ultrahigh-strength and large-span reversible adhesive enabled by a branched oligomer controllable self-aggregation strategy is developed. The dense covalent bonds present in the branched oligomers greatly enhance adhesion strength without compromising reversibility. The resulting adhesive exhibits a large-span reversible adhesion of ≈140 times, switching between ultra-strong and tough adhesion strength (5.58MPa and 5093.92Nm-1) and ultralow adhesion (0.04MPa and 87.656Nm-1) with alternating temperature. Moreover, reversible dynamic double cross-linking endows the adhesive with stable reversible adhesion transitions even after 100 cycles. This reversible adhesion property can also be remotely controlled via a voltage of 8V, with a loading voltage duration of 45s. This work paves the way for the design of reversible adhesives with long-span outstanding properties using covalent polymers and offers a pathway for the rational design of high-performance adhesives featuring both robust toughness and exceptional reversibility.

Use of Renewable Alcohols in Autocatalytic Production of Aspen Organosolv Lignins.

This study aimed to investigate the intrinsic efficiency of renewable alcohols, applied under autocatalytic conditions, for removing lignin from aspen and hot-water-extracted aspen while substantially preserving the lignin structure so as to facilitate various valorization strategies. Ethylene glycol (EG), propylene glycol (PG), 1,4-butanediol (BDO), ethanol (EtOH), and tetrahydrofurfuryl alcohol (THFA) were evaluated based on their lignin solubilization ability, expressed as the relative energy difference (RED) following the principles of the Hansen solubility theory. The findings indicate that alcohols with a higher lignin solubilization potential lead to increased delignification, almost 90%, and produce a lignin with a higher content of β-O-4 bonds, up to 68% of those found in aspen milled wood lignin, thereby indicating their potential for valorization through depolymerization. However, these alcohols also produce lignin with a higher content of β-β and β-5 bonds, resulting in a higher molecular weight and polydispersity, due to readily occurring homolytic reactions. Hot-water extraction (HWE) conducted prior to alcohol treatment reduced the delignification efficiency and resulted in a lignin with a lower β-O-4 bond content. The lignins produced in these experiments exhibited a superior UV-A absorption capacity compared with synthetic benzophenone, as well as a greater radical quenching ability than synthetic butylated hydroxytoluene, indicating their potential for use in the protection of polymers against degradation.

Effect of phosphorylated long‐chain inulin on the quality characteristics of fresh noodles

AbstractIn this paper, phosphorylation was employed to modify long‐chain inulin (PFXL) with the aim of improving the hydrophilicity and stability, thereby enhancing the nutritional value and quality of fresh wheat noodles. The textural characteristics, color, moisture distribution, and microstructure of the fresh noodles, as well as the secondary structure and disulfide bond content of gluten protein, were analyzed. The results indicate a significant enhancement in the quality of fresh noodles with the addition of PFXL. Specifically, the substitution of 6.0% PFXL for wheat flour yielded the highest springiness and whiteness in the fresh noodles. PFXL addition facilitated the transition of tightly bound water to weakly bound and free water within the noodle system, thereby contributing to the softness of the noodles. Furthermore, the introduction of 6% PFXL promoted the formation of a greater number of hydrogen and disulfide bonds, resulting in a higher content of α‐helix and β‐sheet structures. This collective effect served to enhance the overall quality of the noodles. These findings provide valuable insights into the potential applications of long‐chain inulin and offer compelling evidence for the production of high‐quality dietary fiber noodles.

Enhancing freeze-thaw stability of frozen dough with deacetylated konjac glucomannan: The role of degree of deacetylation

The effect of different degrees of deacetylation (DDs) of deacetylated konjac glucomannan (DKGM) on the gluten structure, water state, and yeast activity of frozen dough was evaluated. The moderate DKGM group maintained a more continuous gluten network after three freeze-thaw cycles, as evidenced by an 8.67% increase in disulfide bond content and a 15.01% increase in α-helix content compared to the KGM group. DKGM effectively impeded bound water migration, with the moderate DKGM group retaining 8.28% more bound water than the KGM group after three freeze-thaw cycles. The stabilization of gluten structure and water state in frozen dough by DKGM resulted in higher yeast activity in the low and moderate deacetylation groups (DD = 31.31% and 50.24%). Additionally, DKGM enhanced the quality of frozen steamed bread. The results indicate that DKGM with a moderate DD (50.24%) effectively alleviates the quality deterioration of frozen dough. These findings suggest that DKGM has great potential as a novel cryoprotectant for frozen dough, with DD being a crucial factor in its cryoprotective effect.

A food for elders with dysphagia: Effect of sodium alginate with different viscosities on the gel properties of antarctic krill composite shrimp surimi

This study investigated the effects of sodium alginate (SA) with different viscosities on the physicochemical properties and structure of composite shrimp surimi gels made from Antarctic krill and Litopenaeus vannamei. Changes in texture, rheology, water status, thermal stability, chemical bonding, zeta potential, and microstructures of the gels were analyzed to explore their feasibility as food products for individuals with dysphagia. The addition of SA addition increased the chewiness, absolute value of zeta potential, WHC, and thermal stability of the composite shrimp surimi gels. Concurrently, it decreased the gel strength and the content of chemical bonds, such as ionic and hydrogen bonds, with these changes being more significant at higher SA viscosities. The water distribution analysis showed that increasing SA viscosity increased the content of immobilized water within the gels and stabilized the water. From the perspective of zeta potential and microstructure, higher SA viscosities significantly increased the absolute value of zeta potential, enhanced the electrostatic repulsion and spatial potential resistance, and resulted in larger microstructural gaps, which improved the moisture-trapping capacity and WHC of the gels. The microstructure was more homogeneous and continuous at an SA viscosity of 800 mPa s. International Dysphagia Dietary Standardization Initiative (IDDIS) testing showed that gels with added SA can be classified into Tier 6 dysphagia diets. These findings provide insights for developing nutritious dysphagia-suitable foods for elders.

3D printing of reprogrammable liquid crystal elastomers with exchangeable boronic ester bonds

Liquid crystal elastomers (LCEs) are a kind of soft actuating materials with large reversible deformation ability, which can work as the “motor” to exhibit complex deformations and drive the locomotion of soft robots. The deformation of LCEs depends on the three-dimensional (3D) shape of whole structure and alignment patterns of mesogens. Various methods have been employed to fabricate the LCE structure with desired shapes and mesogen alignments. However, conventional 3D printed LCEs require continuous thermal energy input to maintain their actuated shapes. The LCEs cannot be reprocessed and reprogrammed once cured. Herein, we introduce dynamic boronic ester bonds into the ink, with which the printed LCE structures are capable of being reprogrammed from polydomain into monodomain state and vice versa. We further explore the effects of printing parameters and content of dynamic covalent bonds on the actuation performance and reprogramming ability. The actuated shape could be well predicted with finite element method. The dynamic printable LCEs developed here offer new strategy and large design space for LCE structures.

Morphology of films deposited on the sidewall during the Bosch process using C4F8 plasmas

In the Bosch process, C4F8 plasmas are used to deposit passivation films. In this study, the passivation films were deposited in micro-scale trenches by changing the C4F8 flow rate, ICP power, and pressure, and their cross sections were observed by scanning electron microscopy. The results showed that the morphology of the passivation film and its relative deposition rate at each depth varied depending on the plasma discharge conditions. There is a correlation between the C–CF x bond content and the morphology of passivation films, with high C–CF x bond content resulting in smooth morphology and low C–CF x bond content resulting in a rough morphology. Furthermore, it was found that ion bombardment reduced the roughness of the passivation film. Through these experiments, we also found the possibility of controlling the deposition rate of the passivation film at each trench depth by adjusting the plasma discharge conditions.

Fabrication and Tribological Properties of Diamond-like Carbon Film with Cr Doping by High-Power Impulse Magnetron Sputtering

The present study aims to investigate the advantages of diamond-like carbon (DLC) films in reducing friction and lubrication to address issues such as the low surface hardness, high friction coefficients, and poor wear resistance of titanium alloys. Cr-doped DLC films were deposited by high-power impulse magnetron sputtering (HiPIMS) in an atmosphere of a gas mixture of Ar and C2H2. The energy of the deposited particles was controlled by adjusting the target powers, and four sets of film samples with different powers (4 kW, 8 kW, 12 kW, and 16 kW) were fabricated. The results showed that with an increase in target power, the Cr content increased from 3.73 at. % to 22.65 at. %; meanwhile, the microstructure of the film evolved from an amorphous feature to a nanocomposite structure, with carbide embedded in an amorphous carbon matrix. The sp2-C bond content was also increased in films, suggesting an intensification of the film’s graphitization. The hardness of films exhibited a trend of initially increasing and then decreasing, reaching the maximum value at 12 kW. The friction coefficient and wear rate of films showed a reverse trend compared to hardness variation, namely initially decreasing and then increasing. The friction coefficient reached a minimum value of 0.14, and the wear rate was 2.50 × 10−7 (mm3)/(N·m), at 8 kW. The abrasive wear was the primary wear mechanism for films deposited at a higher target power. Therefore, by adjusting the target power parameter, it is possible to control the content of the metal and sp2/sp3 bonds in metal-doped DLC films, thereby regulating the mechanical and tribological properties of the films and providing an effective approach for addressing surface issues in titanium alloys.

Effects of fish skin collagen peptide on physicochemical properties of frozen dough and quality and antioxidant activity of steamed bread

Fish skin collagen peptide (FSCP), as a bioactive peptide, holds significant potential in the food industry, particularly in enhancing the quality and nutritional attributes of frozen dough products. This research examined the impacts of FSCP addition and freezing time on water distribution, rheo-fermentation, rheological, and structural properties of dough, as well as the textural properties, internal structure, and antioxidant activity of steamed bread. The results showed that adding FSCP inhibited water migration and reduced freezable water content. After 4 weeks of freezing, the freezable water content of the FSCP-added groups decreased by 0.42%–4.77% compared with the control. Rheo-fermentation analysis indicated that the total CO2 release volume, maximum dough development height, and CO2 retention volume initially increased with FSCP concentration, peaking at 1.5%, before decreasing with further increases in FSCP concentration. Moreover, FSCP effectively mitigated gluten freeze damage, resulting in a slower decline in disulfide bond content and viscoelasticity. Additionally, it improved the textural properties and antioxidant activity of the steamed bread. X-ray micro-CT images revealed that FSCP improved gas pore distribution and network density in the steamed bread. Overall, FSCP proved effective in improving the attributes of frozen dough and the final steamed bread, particularly at a 1.5% concentration. These findings suggest a promising application of FSCP in frozen dough-based products, especially in the development of functional foods.

Advanced manufacturing of high conductive graphene coatings on polyethylene terephthalate substrate through laser-induced processes and thermal optimization

Graphene holds immense promise for applications in sensors due to its exceptional properties such as large carrier mobility and high electrical and thermal conductivities. Nevertheless, the manufacture of high conductive graphene films onto flexible substrates remains a formidable challenge. This paper presented a novel method for the precise incorporation of high conductive graphene coatings onto polyethylene terephthalate (PET) through the back transfer of laser-reduced graphene oxide (LRGO) from Al2O3 ceramic to PET. A record-low sheet resistance for LRGO so far, approximately 12 Ω/sq. was achieved, meantime exhibiting 5B level adhesion performance with PET substrate. The sheet resistance of the transferred LRGO was measured and demonstrated to be adjustable by manipulating laser power, scanning speed, and hatch distance. The analysis of reduction of graphene oxide (GO) involved a comprehensive examination of alterations in topography image, chemical bond content, C/O atomic ratio, and ID/IG intensity ratio. These observations provided insights into the factors contributing to the decrease of sheet resistance within LRGO. The adoption of a continuous gigahertz (GHz) femtosecond laser as the light source, coupled with the incorporation of thermally conductive Al2O3 plate as a heat sink, facilitated the manufacturing processes including reduction and transfer of GO. The manufacture of graphene coatings with high electrical conductivity on PET in a versatile and cost-effective manner, presents significant potential for diverse applications, particularly in conductive-coatings-based sensors.

Polyacrylate epoxide oligomers with robust photo‐crosslinked and thermomechanical properties enabled by controlling copolymerizing molecular weight distribution

AbstractPhoto‐triggering curing coatings have advantages of improving production efficiency, reducing pollution emissions, and contributing to green environmental protection. However, making the trade‐off between appropriate viscosity and UV‐curing properties in a high‐performing polymer system remains a formidable challenge. In this paper, firstly, a series of acrylate copolymer oligomers (named as PAAR) were synthesized using methyl methacrylate (MMA), butyl acrylate (BA), and glycidyl methacrylate (GMA), then methacrylic acid (MAA) was grafted utilizing the reaction between carboxyl group in MAA with epoxy group in oligomer to introduce double bonds. By adjusting the oligomer molecular weight to control the viscosity and changing the GMA ratio to obtain suitable double bonds content. As a result, the number molecular weight (Mn) of the thus‐obtained PAAR oligomers were less than 3000 Da, and the polymer dispersity indexes (PDI) were lower than 1.8. Photo‐polymerization kinetics revealed that the coating prepared using the oligomers could be fully cross‐linked by UV light triggering within 60 s, achieving a high transparency of 90% along with favorable thermal and mechanical properties. Furthermore, it was confirmed that the water resistance on the surface of the cured films and hydrophobicity were more influenced by the presence of hydroxyl groups.

Effect of Zanthoxylum bungeanum extract on the quality and cathepsin L activity of Niuganba

Niuganba (NGB) is a traditional fermented beef product. Protease activity typically significantly affects the quality of NGB. Some natural food extracts may markedly influence NGB's protease activity and performance. This study aims to investigate the effect of Zanthoxylum bungeanum extract (ZBE) on the quality and cathepsin L activity of NGB. Following ZBE treatment, the myofibril fragmentation index (MFI), the content of TCA-soluble peptides, surface hydrophobicity, disulfide bond content, and cathepsin L activity of NGB significantly decrease. The content of free thiol groups and β-sheet significantly increases. Scanning electron microscopy (SEM) reveals that the arrangement of muscle fibers in the cross-section of NGB is more compact after ZBE treatment. The research results indicate that ZBE effectively inhibits cathepsin L activity, alleviates the degradation of myofibrillar proteins, improves the physicochemical characteristics of NGB, and enhances its structural stability.

Evaluation of the Ocular Safety of Hollow Mesoporous Organosilica Nanoparticles with Different Tetrasulfur Bond Content.

Drug therapy for eye diseases has been limited by multiple protective mechanisms of the eye, which can be improved using well-designed drug delivery systems. Mesoporous silica nanoparticles (MSNs) had been used in many studies as carriers of therapeutic agents for ocular diseases treatment. However, no studies have focused on ocular biosafety. Considering that MSNs containing tetrasulfur bonds have unique advantages and have drawn increasing attention in drug delivery systems, it is necessary to explore the ocular biosafety of tetrasulfur bonds before their widespread application as ophthalmic drug carriers. In this study, hollow mesoporous silica nanoparticles (HMSNs) with different tetrasulfur bond contents were prepared and characterized. The ocular biosafety of HMSN-E was evaluated in vitro on the three selected ocular cell lines, including corneal epithelial cells, lens epithelial cells and retinal endothelial cells (HREC), and in vivo by using topical eye drops and intravitreal injections. In cellular experiments, HMSNs caused obvious S content-dependent cytotoxic effect. HMSNs with the highest tetrasulfur bond content (HMSN-E), showed the highest cytotoxicity among all the HMSNs, and HREC was the most vulnerable cell to HMSN-E. It was shown that HMSN-E could react with intracellular GSH to generate H2S and decrease intracellular GSH concentration. Treatment of HREC with HMSN-E increased intracellular ROS, decreased mitochondrial membrane potential, and induced cell cycle arrest at the G1/S checkpoint, finally caused apoptosis and necrosis of HREC. Topical eye drops of HMSN-E could cause corneal damage. The intravitreal injection of HMSN-E could induce inflammation in the vitreum and ganglion cell layers, resulting in vitreous opacities and retinal abnormalities. The incorporation of tetrasulfur bonds into HMSN can have toxic effects on ocular tissues. Therefore, when mesoporous silica nanocarriers are designed for ophthalmic pharmaceuticals, the ocular toxicity of the tetrasulfur bonds should be considered.

Effect of alkaline treatment duration on rapeseed protein during pH-shift process: Unveiling physicochemical properties and enhanced emulsifying performance

This study aims to investigate the influence of alkaline treatment duration (0–5 h) on the physicochemical properties and emulsifying performance of rapeseed protein during pH-shift process. Results showed that a 4-h alkaline treatment significantly reduced the particle size of rapeseed protein and led to a notable decrease in disulfide bond content, as well as alterations in subunit composition. Moreover, solubility of rapeseed protein increased from 18.10 ± 0.13% to 40.44 ± 1.74% post-treatment, accompanied by a ∼ 40% enhancement in emulsifying properties. Morphological analysis revealed superior plasticity and sharper contours in 4-h alkali-treated rapeseed protein emulsions compared to untreated counterparts. Rheological analysis indicated higher viscosity and elasticity in the alkali-treated group. Overall, 4-h alkaline treatment markedly enhanced the multifaceted functional attributes of rapeseed protein during pH-shift process, rendering it a promising emulsifier in the food industry.

Atomic-scale understanding on the influence of sliding angle on the interfacial structure and friction behavior of textured amorphous carbon films

Textured amorphous carbon (T:a-C) films have received great attention in the fields of hard drives, MEMS, and NEMS due to their excellent tribological properties. However, there is still a lack of research on the dependence of its friction behavior on different sliding angles. Especially, owing to the limitations of in-situ characterization in capturing the friction interface information, the potential friction mechanisms are still unclear. Hence, in this work T:a-C film with a rectangular shape was constructed and the impact of different sliding angles on friction behavior under dry friction condition was mainly explored through reactive molecular dynamics simulation. Results unveil that the friction properties of T:a-C films are closely dependent on the sliding angle. When the sliding angle increases from 0° to 45°, the decrease in the number of CC covalent bonds at the friction interface weakens the interfacial crosslinking effect, leading to a decrease in the friction coefficient by 20.11 %. However, as the sliding angle further increases from 45° to 90°, an increase in friction coefficient is observed, which is due to the increase of unsaturated bond content, weakening the interface passivation effect. These results reveal the friction mechanism of T:a-C films, induced by sliding angle, and effectively guide the design and technical application of textured a-C films.

Co-pyrolysis of cellulose and lignin: Effects of pyrolysis temperature, residence time, and lignin percentage on the properties of biochar using response surface methodology

Cellulose, hemicellulose, and lignin constitute the basic components of biomass. Knowledge of the interactions between cellulose and lignin during pyrolysis is crucial for unraveling the pyrolysis characteristics of biomass. In this study, for the co-pyrolysis of cellulose and lignin to produce biochar, three influencing factors were selected: pyrolysis temperature (400–800 °C), residence time (5–30 min), and lignin percentage (0–100 %). Pyrolysis experiments were conducted in a vertical tube furnace and the impact of these three factors on the characteristics of biochar was comprehensively explored employing response surface methodology. The results revealed obvious differences between actual values and theoretical values. Specifically, the results showed that the interaction between cellulose and lignin increased the biochar yield, oxygen content, volatile content, and ash content by 6.14 %, 22.85 %, 30.95 %, and 46.75 %, respectively. In contrast, the carbon content, fixed carbon content, and HHV of biochar were relatively reduced by 9.38 %, 11.80 %, and 3.3 %, respectively. Furthermore, Raman spectra of biochar showed that the actual value of graphitization degree of biochar was higher than the theoretical value. This was further corroborated by XPS analysis, wherein owing to the interactions between cellulose and lignin, the actual C-C bond content decreased in contrast to the theoretical value. However, the contents of C-O, CO, COOH functional groups, and aromatic rings increased. Finally, the summary of the co-pyrolysis rules of cellulose and lignin provided a reference for optimal pyrolysis conditions and understanding the mechanism of co-pyrolysis.

Tuning the Metal-Support Interaction by Modulating CeO2 Oxygen Vacancies to Enhance the Toluene Oxidation Activity of Pt/CeO2 Catalysts.

In this research, a range of Pt/CeO2 catalysts featuring varying Pt-O-Ce bond contents were developed by modulating the oxygen vacancies of the CeO2 support for toluene abatement. The Pt/CeO2-HA catalyst generated a maximum quantity of Pt-O-Ce bonds (possessed the strongest metal-support interaction), as evidenced by the visible Raman results, which demonstrated outstanding toluene catalytic performance. Additionally, the UV Raman results revealed that the strong metal-support interaction stimulated a substantial increase in oxygen vacancies, which could facilitate the activation of gaseous oxygen to generate abundant reactive oxygen species accumulated on the Pt/CeO2-HA catalyst surface, a conclusion supported by the H2-TPR, XPS, and toluene-TPSR results. Furthermore, the results from quasi-in situ XPS, in situ DRIFTS, and DFT indicated that the Pt/CeO2-HA catalyst with a strong metal-support interaction led to improved mobility of reactive oxygen species and lower oxygen activation energies, which could transfer a large number of activated reactive oxygen species to the reaction interface to participate in the toluene oxidation, resulting in the relatively superior catalytic performance. The approach of tuning the metal-support interaction of catalysts offers a promising avenue to develop highly active catalysts for toluene degradation.

PECVD technology deposition of high hardness a-C:H films on micro-drill surfaces: Substrate bias voltage effects

The plasma enhanced chemical vapor deposition (PECVD) technique was utilized to produce hydrogenated amorphous carbon (a-C:H) films. The overall structure of the films consists of a Cr/WC transition layer, a WC/a-C:H transition layer, and an a-C:H functional layer. The study investigated the effects of substrate bias voltages (SBVs) of −580 V, −660 V, −740 V, −820 V, and −900 V on the microstructure, mechanical, and tribological properties of a-C:H films. The findings indicate that different SBVs influence the ionic energy during the deposition of a-C:H films, consequently affecting the film growth. In this case, when the SBV is -820 V, C+ with sufficient energy will penetrate beneath the initial layer in the form of shallow injection. Therefore, compared to other experimental groups, the a-C:H films prepared under this condition have the lowest Ra value (0.42 nm), the highest sp3 CC bond content (39.88 %), the maximum hardness (31.6 GPa), the lowest friction coefficient (0.052), and the smallest wear rate (7.48 × 10−8 mm3/(N·m)), demonstrating significantly better mechanical and tribological properties. The a-C:H films, prepared at different SBVs, are deposited on micro-drill surfaces for hole drilling tests. The experimental results indicate that a-C:H films prepared at SBV of −820 V exhibit the satisfactory drilling performance due to the better mechanical and tribological properties. This is evident not only in the minimal surface wear of the film micro-drill after different drilling quantities but also by the satisfactory quality of the corresponding machined holes. The a-C:H film micro-drill prepared at SBV of −820 V exhibited larger process capability index (CPK) values for the machined holes at 500, 1000, and 2000 hole numbers of 5.449, 3.693, and 3.263 respectively. During the 2000th drill on the printed circuit board (PCB) surface, the hole wall roughness (Rz) and nail head values of the machined hole were measured to be 10.6 μm and 1.3, respectively.

Effect of γ-oryzanol/β-sitosterol-based oleogels on the physicochemical and gel properties of Nemipterus virgatus myofibrillar protein.

The effect of oleogels prepared with peanut oil and different concentrations of γ-oryzanol and β-sitosterol mixture (γ/β; 20, 40, 60, 80 and 100 g kg-1) on the physicochemical and gel properties of myofibrillar protein (MP) was investigated. The solubility and average particle size of MP first decreased and then increased with increasing γ/β concentration. Peanut oil or oleogels could induce the exposure of hydrophobic amino acids and the unfolding of MP, thus significantly increasing the surface hydrophobicity, sulfhydryl content and absolute value of zeta potential, which reached maximum values when the γ/β concentration was 60 g kg-1 (P < 0.05). The addition of peanut oil decreased the gel strength and water holding capacity of MP gel. However, oleogels prepared with 60 g kg-1 γ/β could significantly increase the hydrophobic interactions and disulfide bond content of MP gel (P < 0.05), which promoted the crosslinking and aggregation of MP, enhancing the gel properties. Peanut oil had no significant influence on the secondary structure of MP, while oleogels promoted the transition of MP conformation from α-helix to β-sheet structure. The results of light microscopy and confocal laser scanning microscopy indicated that oleogels prepared with 60 g kg-1 γ/β filled in the pores of MP gel network to form denser and more uniform structure. Oleogels prepared with 60 g kg-1 γ/β could effectively improve the quality of MP gel and have promising application prospects in surimi products. © 2024 Society of Chemical Industry.

Chemical Synthesis of Atactic Poly-3-hydroxybutyrate (a-P3HB) by Self-Polycondensation: Catalyst Screening and Characterization.

Poly-3-hydroxybutyrate (P3HB) is a biodegradable polyester produced mainly by bacterial fermentation in an isotactic configuration. Its high crystallinity (about 70%) and brittle behavior have limited the process window and the application of this polymer in different sectors. Atactic poly-3-hydroxybutyrate (a-P3HB) is an amorphous polymer that can be synthesized chemically and blended with the isotactic P3HB to reduce its crystallinity and improve its processability Ring-opening polymerization (ROP) is the most cited synthesis route for this polymer in the literature. In this work, a new synthesis route of a-P3HB by self-polycondensation of racemic ethyl 3-hydroxybutyrate will be demonstrated. Different catalysts were tested regarding their effectiveness, and the reaction parameters were optimized using titanium isopropoxide as the catalyst. The resulting polymers were compared by self-polycondensation for their properties with those of a-P3HB obtained by the ROP and characterized by Fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC), and the double bond content (DBC) was determined by UV-VIS spectroscopy by using 3-butenoic acid as a standard. Additionally, a life cycle analysis (LCA) of the new method of synthesizing has been carried out to assess the environmental impact of a-P3HB.