Polycondensation Of Acid Research Articles

A review of exploring the synthesis, properties, and diverse applications of poly lactic acid with a focus on food packaging application.

Polylactic acid (PLA) is an aliphatic polyester, which is primarily synthesized from renewable resources through the polycondensation or ring-opening polymerization of lactic acid (LA)/lactide. LA can be conveniently produced via the fermentation of sugars obtained from renewable sources such as corn and sugar cane. Due to its biodegradable and biocompatible nature, PLA exhibits a vast range of applications. Its advantages include non-toxicity, environmental safety, and compatibility with human biological systems. PLA finds significant use in various biomedical applications, including implants, tissue engineering, sutures, and drug delivery systems. Additionally, PLA serves as a renewable and biodegradable polymer of extensive utility in film production, offering an alternative to petrochemical-based polymers. Moreover, the properties of PLA-based films can be tailored by incorporating extracts, polysaccharides, proteins, and nano-particles. This review encompasses LA production, PLA synthesis, and diverse applications of PLA and further explores the potential of PLA in the realm of packaging.

Synthesis and Characterization of Poly (Erythritol Sebacate)

AbstractErythritol is a sweetener polyol widely distributed in nature. Its industrial production is based on biotechnological fermentative processes using yeasts. It is used essentially in nutrition and pharmaceutical fields. However, due to its still high price, the use of erythritol is not widespread and is lower than that of other polyols. The use of erythritol for polymer synthesis remains largely unexplored by the scientific community. This work describes the synthesis and characterization of polyester, poly (erythritol sebacate) (PES), obtained by thermal polycondensation of erythritol and sebacic acid in a two steps approach. A prepolymerization step was realized at different temperatures (150 °C, 160 °C and 170 °C, respectively) followed by a cure step at 150 °C. It was found that using a higher temperature allows the same degree of polymerization (50%) to be achieved in a shorter period, but this leads to prepolymers with a more heterogeneous oligomeric composition. This is reflected in the final properties of the polymers after curing. Synthesis at 150 °C produced a polymer with superior mechanical performance (ultimate tensile strength: 0.5 MPa; Young’s modulus: 0.44 MPa: elongation at break: 123%) and higher chemical resistance to solvents than polymers synthesized at 160 °C and 170 °C. The glass transition temperature (Tg) is between − 20 and 0 °C for all polymers and density is 1.08 g/cm3. Based on these results, we believe that PES is a good elastomer with tunable properties and potential for selective absorption of molecules, such as ethanol, that could be useful for beverage industry and biotechnological applications. Graphical Abstract

Intrinsically Microporous Ion-Pair Membranes for HT-PEMFCs

Fuel cells are electrochemical devices with high energy efficiency expected to be applied economically and eco-friendly across various energy sectors. Low-temperature polymer electrolyte membrane fuel cells (LT-PEMFCs) using Nafion operates at a relatively low operating temperature (60-80°C) and fully hydration condition. HT-PEMFC is operable at high temperatures (140-180°C), but requires anhydrous conditions to avoid loss of doped phosphoric acid (PA). In this presentation, polymer membranes designed through with intrinsic microporosity were synthesized through super acid polycondensation. We demonstrated that high proton conductivity (106.33 mS cm-1 at 180℃) is obtained by forming phosphoric acid filled ion-channels within the interconnected microporous structure. Moreover, ion-pair coordinated PIMs are fabricated by methylation of PIMs to improve PA retention even under humidified conditions. It is suggested that the water tolerance of ion-pair coordinated PIMs is improved and can be operated under various conditions regardless of humidification and operating temperature and exceptional membrane electrode assembly performance and durability achieved even under humidified reformate gas conditions.

An atom economy polyamide elastomer derived from polyether amine‐based bis‐acrylamide and dithiol monomer and synthesized by thiol‐Michael addition click reaction

AbstractTraditional polyamide elastomer synthesis via polycondensation of diamines and dicarboxylic acids involves high energy use and by‐product mass loss. Here, we present a novel method using thiol‐Michael addition click chemistry to produce these elastomers under mild conditions, marking the first use of this strategy. The polymerization involves coupling bis‐acrylamide (BAA) with 3,6‐dioxa‐1,8‐octanedithiol (DODT), catalyzed by 1,5‐diazabicyclo[4.3.0]non‐5‐ene (DBN). BAA is synthesized from polyetheramine and acryloyl chloride, creating a compound with amide groups and carbon double bonds at chain ends. These double bonds' electron‐withdrawing effect facilitates the click reaction efficiently, avoiding high energy and mass loss. The resulting polymers have a molecular weight of approximately 10,000 g/mol, verified by 1H NMR and FTIR spectroscopy, which show amide group presence. SAXS and AFM confirm nanophase separation of these groups. Tensile strength ranges from 0.235 to 0.542 MPa, decreasing with lower polyetheramine content but still showing notable elasticity. This method's low energy use, no mass loss, and good mechanical properties make it promising for developing high‐performance polyamide plastics and elastomers, appealing to researchers in both academia and industry.Highlights High elasticity, softness, and high tensile polyamide elastomer. Thiol‐Michael addition click reaction conforms to atomic economy. Long molecular chain contains extraordinary evolution of hydrogen bonding.

Synthesis of Water-Soluble Polyethylene Glycol Fumarates for Biomedical Applications

Polyethylene glycol fumarate (PEGF) with controlled structural composition has been obtained for further synthesis of double network crosslinked hydrogels for biomedical applications. The copolymer has been synthesized by polycondensation reaction of fumaric acid and polyethylene glycol (PEG-600). Molecular weight of PEGF has been determined by gel permeation chromatography to be approximately 6000 Da with gel permeation chromatography. The polycondensation of fumaric acid and PEG-600 was studied throughout the reaction process. The structure of the reaction product has been evidenced using FTIR- and 1H NMR-spectroscopy. The quantitative ratios of the amount of –C=C– bonds and –COO groups to –C=O groups in the obtained PEGF have been estimated from IR-spectra for different synthesis time. The time-dependence of molar ratio of double bonds to methyl groups in PEGF has been obtained from corresponding 1H NMR-spectra. FTIR and 1H NMR-spectroscopy, both, demonstrate that after the end of reaction the unsaturated –C=C– double bonds remain in the structure of the macromonomer, that is essential for further preparation of cross-linked hydrogels. The addition of the tightly cross-linked network of polyvinyl alcohol leads to formation of highly tough biocompatible material for preparation of the artificial meniscus which can further be used as a solution n the treatment of diseases such as osteoarthritis.

Synthesis and characterization of a dithiodiglycolic acid-incorporated poly(glycerol sebacate) exhibiting lipase resistance and antibacterial properties

Poly(glycerol sebacate) (PGS), a crosslinked network synthesized by polycondensation of glycerol and sebacic acid, has found successful utilization in various tissue engineering applications because of its biocompatibility, ease of synthesis, surface-erosion biodegradability, rubber-like elasticity, and adjustable mechanical properties. However, its fast in vivo degradation and lack of intrinsic antibacterial activity may be a concern for specific applications. The functional groups of glycerol and sebacic acid can react with those of other monomers, offering unlimited possibilities for generating new crosslinked networks tailored for particular purposes. Herein, we synthesized a series of poly(glycerol sebacate dithiodiglycolate) (PGSDTG) by incorporation of dithiodiglycolic acid (DTG) in the synthesis of PGS. PGSDTG exhibited reduced stiffness, sensitivity to glutathione (GSH), resistance to lipase degradation, and inhibition of bacterial adhesion and growth. The PGSDTG containing 45.6 wt% of DTG exhibited the lowest degradation rate with more than 80 wt% of PGSDTG remained at day 28 and the lowest bacterial inactivation rates of 99.2 ± 0.5 % and 82.5 ± 11.0 % against S. aureus and E. coli, respectively. This study suggested that PGSDTG may serve as a suitable antibacterial scaffold material for repairing or regenerating tissues characterized by a slow healing rate.

Synthesis, Structure and Properties of Polyester Polyureas via a Non-Isocyanate Route with Good Combined Properties.

Polyureas have been widely applied in many fields, such as coatings, fibers, foams and dielectric materials. Traditionally, polyureas are prepared from isocyanates, which are highly toxic and harmful to humans and the environment. Synthesis of polyureas via non-isocyanate routes is green, environmentally friendly and sustainable. However, the application of non-isocyanate polyureas is quite restrained due to their brittleness as the result of the lack of a soft segment in their molecular blocks. To address this issue, we have prepared polyester polyureas via an isocyanate-free route and introduced polyester-based soft segments to improve their toughness and endow high impact resistance to the polyureas. In this paper, the soft segments of polyureas were synthesized by the esterification and polycondensation of dodecanedioic acid and 1,4-butanediol. Hard segments of polyureas were synthesized by melt polycondensation of urea and 1,10-diaminodecane without a catalyst or high pressure. A series of polyester polyureas were synthesized by the polycondensation of the soft and hard segments. These synthesized polyester-type polyureas exhibit excellent mechanical and thermal properties. Therefore, they have high potential to substitute traditional polyureas.

Zinc hybrid polyester barrier membrane accelerates guided tissue regeneration

Barrier membranes play a pivotal role in the success of guided periodontal tissue regeneration. The biodegradable barriers predominantly used in clinical practice often lack sufficient barrier strength, antibacterial properties, and bioactivity, frequently leading to suboptimal regeneration outcomes. Although with advantages in mechanical strength, biodegradability and plasticity, bioinert aliphatic polyesters as barrier materials are usually polymerized via toxic catalysts, hard to be functionalized and lack of antibacterial properties. To address these challenges, we propose a new concept that controlled release of bioactive substance on the whole degradation course can give a bioinert aliphatic polyester bioactivity. Thus, a Zn-based catalytic system for polycondensation of dicarboxylic acids and diols is created to prepare zinc covalent hybrid polyester (PBS/ZnO). The atomically-dispersed Zn2+ ions entering main chain of polyester molecules endow PBS/ZnO barrier with antibacterial properties, barrier strength, excellent biocompatibility and histocompatibility. Further studies reveal that relying on long-term controlled release of Zn2+ ions, the PBS/ZnO membrane greatly expedites osteogenetic effect in guided tissue regeneration (GTR) by enhancing the mitochondrial function of macrophages to induce M2 polarization. These findings show a novel preparation strategy of bioactive polyester biomaterials based on long term controlled release of bioactive substance that integrates catalysis, material structures and function customization.

Synthesis and Modeling of Poly(L-lactic acid) via Polycondensation of L-Lactic Acid.

We present synthetic experiments of lactic acid (LA) polycondensation to produce poly(lactic acid) (PLA) as well as kinetic modeling calculations that capture the polymer molecular weight increase with time, given the initial concentrations. Tin-octoate-catalyzed polycondensation of (D,L)- or L-lactic acid was carried out in pre-dried toluene after azeotropic dehydration for 48-120 h at 130-137 °C. The polymerization was optimized by varying lactic acid and catalyst concentrations as well as the temperature. Gel permeation chromatography was used to experimentally follow the evolution of molecular weights and the products were characterized by NMR, TGA, DSC and IR. Under optimal conditions, PLLA with weight-average molecular weight (Mw) of 161 kDa could be obtained. The rate equations that describe polycondensation kinetics were recast in a condensed form that allowed very fast numerical solution and calculation of the number-average molecular weight with time. Deviations with respect to the experiment were minimized in a least-squares fashion to determine rate constants. The optimized kinetics parameters are shown to reproduce the experimental data accurately.

Effectiveness of different immobilized Candida antarctica lipase b (iCaLB) in the production of biobased oligoester derivatives from poly(butylene succinate) (PBS) and poly(butylene adipate) (PBA)

The use of lipases (Candida antarctica Lipase B, CaLB) immobilized on different solid supports for the preparation of biodegradable aliphatic polyesters poly(butylene adipate) (PBA) and poly(butylene succinate) (PBS) by esterification of unactivated dicarboxylic acids with 1,4-butanediol is presented. The immobilization of CaLB through absorption or a covalent attachment to different solid supports enhances their use as a catalyst for polycondensation reactions both in solution and in bulk. The results indicated that the different immobilized CaLBs were able to catalyze succesfully the polycondensation of both succinic and adipic acid with 1,4-butanediol, yielding the linear aliphatic polyesters PBS and PBA, respectively, by using a two-step polymerization process. Techniques such as nuclear magnetic resonance (NMR), relative molar mass obtained by gel permeation chromatography (GPC) and differential scanning calorimetry (DSC) were applied to compare the influence of the solid support on the obtention of PBA and PBS. Herein, it is shown that the nature of the solid support employed on each immobilized CaLB enzyme modifies the activity and effectivity towards polycondensation of PBA and PBS having a strong influence on the molecular weights and crystallinity.

Synergistic selective photocleavage of lignin C–C bonds by triazine-rich tubular carbon nitride and high-temperature oxidation treatment

The key issue in lignin conversion depends on cutting the β-O-4 linkage bonds between units while keeping the aromatic ring intact. Triazine-heptazine homopolymers of carbon nitride are more prone to break the Cβ-H bond in the β-O-4 bond and generate the critical Cβ radical compared to the triazine or heptazine structure. Triazine-rich g-C3N4 was successfully prepared by ball milling-thermal polycondensation of melamine and cyanuric acid, which has the advantage of low cost and no desalting compared to the conventional eutectic salt method. The triazine-rich g-C3N4 has higher photocurrent density, lower photogenerated electron-transfer resistance, and less electron-hole recombination. Combined with high-temperature oxidation treatment, g-C3N4-O-Q-A5 has an excellent selective photocleavage efficiency of lignin β-O-4 bonds, which is 340 % higher than that of untreated g-C3N4. This paper reveals that the localization of holes in the photocleavage β-O-4 bond reaction, and the amount of superoxide radical generation are the main factors limiting the photocleavage efficiency.

Phosphorylated Polyesters Inspired by Phospholipids: Synthesis, Characterization, and Potential Applications.

We report the synthesis of phosphorylated polyesters by the phosphorylation of hydroxylated polyesters synthesized by the lipase-catalyzed polycondensation of glycerol and aliphatic dicarboxylic acids and their characterization. The use of phosphoryl chloride as a phosphorylating agent and triethylamine as a catalyst in mild reaction conditions resulted in polyesters with repetitive units structurally similar to phospholipids, molar mass of around 14-38 kDa, and a degree of phosphorylation of 36 ± 11 mol %. These polyesters are composed mainly of 10 different repetitive units as determined by 1D and 2D NMR. Their properties change from more hydrophilic and amorphous for phosphorylated poly(glycerol adipate) to more hydrophobic and semicrystalline for phosphorylated poly(glycerol dodecanedioate). Preliminary investigations have shown the potential of these polyesters to self-assemble in aqueous media forming nanoparticles, which can be loaded with hydrophobic molecules and released into an organic phase, acting as a phase transfer agent, and used as a pH-responsive emulsifier.

Competitive assembling strategy to construct carbon nitride homojunctions for boosting photocatalytic performance

Both morphology and composition have a great influence on the properties and functions of materials, however, how to rational modulate both of them to achieve their synergistic effects has been a long-standing expectation. Herein, we demonstrate a competitive assembling strategy for the construction of metal-free graphite carbon nitride (CN) homojunctions in which morphology and composition can be easily controlled simultaneously by only changing the ratio of assembly raw materials. These homojunctions are comprised of porous nanotubular S-doped CN (SCN) grafted with CN nanovesicles, which are derived from thermal polycondensation of melamine-thiocyanuric acid (M-T)/melamine-cyanuric acid (M-C) supramolecular hybrid blocks. This unique architecture and component engineering endows the novel SCN–CN homojunction with abundant active sites, enhanced visible trapping ability, and intimate interface contact. As a result, the synthesized SCN–CN homojunctions demonstrate high photocatalytic activity for hydrogen evolution and pollutant degradation. This developed strategy opens up intriguing opportunities for the rational construction of intricate metal-free heterostructures with controllable architecture and interfacial contact for applications in energy-related fields.

Poly lactic acid production using the ring opening polymerization (ROP) method using Lewis acid surfactant combined iron (Fe) catalyst (Fe(DS)3)

LASC catalyst synthesis process was carried out using iron metal (Fe) and its characterization properties were tested. There are five stages carried out, namely, the manufacture of the LASC Fe(DS)3 catalyst, lactic acid dehydration, polycondensation of lactic acid into l-lactic acid oligomers (OLLA), depolymerization of oligomers into l-lactide, and the ROP process to convert l-lactide into Polymers. l-lactic acid (PLLA). The analysis used is as follows, Karl-Fisher; Spectroscopy Fourier Transform Infrared (FTIR); and Nuclear Magnetic Resonance (HNMR); Gel Permeation Chromatography (GPC); Thermogravimetry Gravity Analysis (TGA) and X-Ray Diffraction (XRD). Based on the experimental results, the catalyst Fe(DS)3 has a crystallinity value of 24% which indicates an amorphous nature and is easy to react. The value of the thermal stability of the catalyst is at 180 °C where the catalyst is able to process up to a temperature of 180 °C. Each step of the ROP is validated by FTIR analysis which shows that the components of the group are in accordance with the expected product. The comparison of the crystallinity values of PLA produced with FeCl3 and Fe(DS)3 were 37.5 and 49%, respectively. Melting temperature (Tm) values are 111 and 107 °C, respectively, Td values are 327 and 352 °C, and the resulting molecular weights are 23,720 and 20,232 g/mol. Based on the results obtained, it can be seen that the use of a LASC catalyst in the form of Fe(DS)3 is more effective than without using a LASC catalyst.

PROCESSING TECHNOLOGIES, PROPERTIES AND APPLICATION OF POLY (LACTIC ACID) (PLA)

Poly (lactic acid) (PLA) is a one of substitutions to fossil-based polymers because they have a less influence on the environment. Material sustainability requirements have increased importance of PLA polymers and others similar biopolymers. PLA polymeris an aliphatic polyester, usually produced by ring-opening polymerization or by polycondensation of lactic acid. For the production of PLA components, melt processing is one of the most commonly used techniques. Today, processing technologies of PLA components include injection moulding, hot pressing, spinning, blow moulding, foam moulding, electrospinning, 3D printing, and so on. PLA polymers have better thermal workability than most bio-based polymers. The analysis of mechanical properties, structure in processes, and an appropriate application of PLA is done in this paper. Also this paper summarizes variations in thermal degradation, recyclability, biodegradation and aging during PLA processing and application. The tensile strength and modulus of elasticity of PLA polymers is similar to those of conventional polyesters. But, because PLA polymers are biodegradable, they can change properties if exposed to uncontrolled temperature and humidity conditions. PLA polymers have lower toughness than those of conventional polyesters. Toughness could be improved by development of PLA composites. PLA is safe for use in the manufacturing of products that are in contact with food. European Food Safety Authority (EFSA) recognize PLA as material which can be safely employed as a food packaging material without causing adverse health effects. PLA possesses barrier properties that are just as effective as LDPE and PS. Limited antibacterial properties of PLA can be improved by application of antibacterial agents. Generally high price of PLA polymers limits their application as a packaging material. Biodegradable PLA polymers are suitable for a wide range of industrial, biomedical and pharmaceutical applications, such as material for medical implants, resorbable prostheses, controlled drug release, biodegradable joints and supports for tissue engineering. Development of processing methods is needed for sufficient increase the industrial application of PLA polymers. Suitable methods to minimize the disadvantages of PLA can be blending PLA with other materials, creating micro- and nanocomposites, coating with high-barrier materials, and polymer modification.

Poly(octamethylene citrate) Modified with Glutathione as a Promising Material for Vascular Tissue Engineering

One of the major goals of vascular tissue engineering is to develop much-needed materials that are suitable for use in small-diameter vascular grafts. Poly(1,8-octamethylene citrate) can be considered for manufacturing small blood vessel substitutes, as recent studies have demonstrated that this material is cytocompatible with adipose tissue-derived stem cells (ASCs) and favors their adhesion and viability. The work presented here is focused on modifying this polymer with glutathione (GSH) in order to provide it with antioxidant properties, which are believed to reduce oxidative stress in blood vessels. Cross-linked poly(1,8-octamethylene citrate) (cPOC) was therefore prepared by polycondensation of citric acid and 1,8-octanediol at a 2:3 molar ratio of the reagents, followed by in-bulk modification with 0.4, 0.8, 4 or 8 wt.% of GSH and curing at 80 °C for 10 days. The chemical structure of the obtained samples was examined by FTIR-ATR spectroscopy, which confirmed the presence of GSH in the modified cPOC. The addition of GSH increased the water drop contact angle of the material surface and lowered the surface free energy values. The cytocompatibility of the modified cPOC was evaluated in direct contact with vascular smooth-muscle cells (VSMCs) and ASCs. The cell number, the cell spreading area and the cell aspect ratio were measured. The antioxidant potential of GSH-modified cPOC was measured by a free radical scavenging assay. The results of our investigation indicate the potential of cPOC modified with 0.4 and 0.8 wt.% of GSH to produce small-diameter blood vessels, as the material was found to: (i) have antioxidant properties, (ii) support VSMC and ASC viability and growth and (iii) provide an environment suitable for the initiation of cell differentiation.

Synthesis of a new pyrimidine-based sorbent for indium(III) removal from aqueous solutions – Application to ore leachate

A new sorbent (TcTDG, pyrimidine derivative, with high content of N-based reactive groups and S-based sites) was successfully synthesized by the polycondensation of thiocarbazide and 2-thiobarbituric acid through reaction with formaldehyde. The material is characterized by FTIR, SEM and SEM-EDX analyses, titration, elemental analysis, BET, and TGA. After interacting with In(III), the FTIR spectrum of TcTDG shows the modification of the environment of N- and S-based reactive groups. The sorption of In(III) is first studied in synthetic solutions with TcTDG micro-particles through the evaluation of pH effect (optimum at pH 4), the uptake kinetics (equilibrium achieved in 20–30 min), the sorption isotherms and the selectivity properties from equimolar solution of different metal ions. The sorption capacity significantly decreases when increasing the temperature from 15 to 50 °C: In(III) sorption onto TcTDG is exothermic. Maximum sorption capacity at room temperature and at pH 4 reaches up to 1.87 mmol In g−1; the isotherm is equally fitted by the Langmuir and the Sips equations. Indium is fully eluted from metal-loaded sorbent using 0.3 M HCl solution (equilibrium reached in 20–30 min). The pseudo-first order rate equation fits well experimental kinetic profile; although the resistance to intraparticle diffusion plays a significant role in the control of In(III) sorption. The sorbent is highly stable at recycling: the FTIR spectrum is restored after five cycles and desorption remains complete along the cycles; after five re-uses, the sorption efficiency decreases by less than 4%. The study is extended to more complex solutions: first, with multi-component synthetic equimolar solutions before investigating the application of TcTDG to metal recovery from acidic leachate of ore sample (from Eastern Central Desert, Egypt). The sorbent shows a marked preference for In(III) at pH 4 against mono-, di- and tri-valent metal ions in synthetic solutions, the preference is also appreciable but the selectivity coefficient (SCIn/metal) is weaker for rare metals (between 3 and 6, vs. 10–35 for other metal ions). In the case of acidic leachate, the pH control to 4 leads to substantial precipitation of huge amounts of iron and the co-precipitation of other metal ions. The sorption capacity for In(III) (and Ga(III)) is significantly reduced by the complexity of the effluents; although the sorbent maintains a preference for these trivalent metal ions. The new sorbent shows promising sorption properties, although complementary investigation is required for optimizing the practical application of this material (conditioning, larger number of recycling steps, etc.).

Functionalized lactic acid macromonomers via polycondensation as an alternative to ring opening polymerization

AbstractEngineered polylactic acid (PLA) nanoparticles synthesized from oligo(lactic acid) macromonomers have been studied over the last decades for controlled drug delivery. These macromonomers are typically produced via ring‐opening polymerization (ROP) of the cyclic dimer lactide, initiated by 2‐hydroxyethyl methacrylate (HEMA). This reaction route, despite leading to well‐defined macromonomers, relies on the production of lactide from lactic acid, which burdens the ROP overall cost for more than 30%. In this work, we report the synthesis of PLA‐based macromonomers by direct polycondensation of lactic acid in the presence of HEMA as a valuable alternative to ROP. In particular, we compare the two processes side by side, focusing on the production of three HEMA‐LAn macromonomers, with n = 2, 4, and 6. Detailed kinetic models are developed for both reaction systems, and the corresponding parameters are estimated by fitting the experimental data. Through these models, the reaction kinetics as well as the time evolution of the entire chain length distributions of the products from polycondensation and ROP could be reliably predicted. This way, we demonstrated that polycondensation is a valuable alternative to ROP only for macromonomers with an average chain length of up to 4 and that ROP remains the main route to longer chains, when a strict control over the chain length distribution is required.

A Novel High Temperature Fuel Cell Proton Exchange Membrane with Nanoscale Phase Separation Structure Based on Crosslinked Polybenzimidazole with Poly(vinylbenzyl chloride)

A semi-aromatic polybenzimidazole (DPBI) is synthesized via polycondensation of decanedioic acid (DCDA) and 3,3-diaminobenzidine (DAB) in a mixed phosphorus pentoxide/methanesulfonic acid (PPMA) solvent. Ascribing to in-situ macromolecular crosslinker of ploly((vinylbenzyl chloride) (PVBC), a robust crosslinked DPBI membrane (DPBI-xPVBC, x refers to the weight percentage of PVBC in the membrane) can be obtained. Comprehensive properties of the DPBI and DPBI-xPVBC membranes are investigated, including chemical structure, antioxidant stability, mechanical strength, PA uptake and electrochemical performances. Compared with pristine DPBI membrane, the PA doped DPBI-xPVBC membranes exhibit excellent antioxidative stability, high proton conductivity and enhanced mechanical strength. The PA doped DPBI-10PVBC membrane shows a proton conductivity of 49 mS cm-1 at 160 °C without humidification. Particularly, it reveals an enhanced H2/O2 single cell performance with the maximum peak power density of 405 mW cm-2, which is 29% higher than that of pristine DPBI membrane (314 mW cm-2). In addition, the cell is very stable in 50 h, indicating the in-situ crosslinked DPBI with a macromolecular crosslinker of PVBC is an efficient way to improve the overall performance of HT-PEMs for high performance HT-PEMFCs.

Vitrimer-like of poly (glycerol sebacate) by using zinc acetate, zinc oxide and Amberlyst as catalysts

Polyglycerol sebacate (PGS) is elastomeric biodegradable polymer with potential biomedical and green packaging applications. This study focuses on the synthesis of vitrimer-like PGS utilizing various catalysts, including Zinc acetate, Zinc oxide and Amberlyst-15. The investigation of vitrimer-like of PGS polymer by polycondensation of glycerol and sebacic acid with various molar ratio of 1:1, 1:1.25 and 1:1.5 will be studied. The synthetic time and temperature were controlled at 72 h, 120 °C, respectively. The prepolymer of PGS had a weight-average molecular weight (Mw.) of 1743. The result of functional group was confirmed by Fourier transforms Infrared spectroscopy (FTIR). The intense CO stretch at 1737 cm−1 confirms the formation of ester bonds. The intense OH stretch at 3454 cm−1 indicated hydroxyl groups from hydrogen bonded. When the quantity of catalyst is increased, the results of hardness are rising but swelling (%) becomes lower. The results showed a polymer network has higher cross-link when the catalyst increases. In addition, the proton nuclear magnetic resonance spectroscopy (1H NMR) analysis found that PGS using catalyst does not have peaks of glycerol.