High Glass Transition Temperature Research Articles

Facile preparation of high-performance plywood adhesive from gelatinized corn starch crosslinked with ammonium dihydrogen phosphate

A flame retardant high-performance gelatinized starch (GS)-ammonium dihydrogen phosphate (ADP) wood adhesive, named GS-ADP adhesive was prepared by condensation of GS and ADP under acidic condition. The preparation process of GS-ADP adhesive is very simple by mixing and stirring GS and ADP evenly at room temperature. The results revealed that the GS-ADP adhesive has good storage stability and water resistance, and its wet shear strength is much higher than that of phenolic resin (PF) adhesive. Markedly, the cone calorimeter test results show that G-ADP adhesive has good flame retardancy, and the plywood based on GS-ADP adhesive has good flame retardancy. Meanwhile, it can be seen from dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA) that GS-ADP has excellent modulus of elasticity (MOE), high glass transition temperature (Tg) and good thermal stability. The findings suggest that GS-ADP could be a viable substitute for PF resin in structural wood fabrication.

Metallized stacked polymer film capacitors for high-temperature capacitive energy storage

Metallized film capacitors towards capacitive energy storage at elevated temperatures and electric field extremes call for high-temperature polymer dielectrics with high glass transition temperature (Tg), large bandgap (Eg), and concurrently excellent self-healing ability. However, traditional high-temperature polymers possess conjugate nature and high S value (C/(H + O) ratio), which compromises Eg and self-healing properties. Herein, we provide a series of novel molecules-fully alicyclic polymers based on commercial Kapton PI (Al-PIs), which exhibit intrinsic decoupling conjugate and decreasing S, leading to high Eg and robust self-healing. The Al-PIs possess much increased Eg of 5.23 eV (Tg of 242 °C) or Eg of 5.01 eV (Tg of 280 °C) with a lowered S < 0.7, which approaches Eg of 5.93 eV and S of 0.5 for the commercial benchmark biaxially oriented polypropylene (BOPP) applied at low temperatures (≤70 °C). Consequently, Al-PI delivers a record discharge energy density with 90 % discharge efficiency (Uη90) of up to 8.04 J/cm3 at 150 °C, 5.74 J/cm3 at 200 °C, and 3.12 J/cm3 at 250 °C, respectively. Besides, Al-PI is capable of self-healing even at 200 °C. We also demonstrate a stacked Al-PI metallized film capacitor with discharge energy density up to 1.6 J/cm3 and discharge efficiency of 98 % at 150 °C. These results confirm that alicyclic polymers are promising candidates for high-performance dielectric films and capacitors under extreme thermal and electric field conditions.

Effect of the Graphene Quantum Dot Content on the Thermal, Dynamic-Mechanical, and Morphological Properties of Epoxy Resin.

Different amounts of graphene quantum dots (CQDs) (0, 1, 2.5, and 5 wt%) were incorporated into an epoxy matrix. The thermal conductivity, density, morphology, and dynamic mechanical thermal (DMTA) properties were reused from the study of Seibert et al.. The Pearson plot showed a high correlation between mass loading, thermal conductivity, and thermal diffusivity. A poorer correlation with density and heat capacity was observed. At lower CQD concentrations (0.1 wt%), the fracture surface showed to be more heterogeneous, while at higher amounts (2.5 and 5 wt%), a more homogeneous surface was observed. The storage modulus values did not change with the CQD amount. But the extension of the glassy plateau increased with higher CQD contents, with an increase of ~40 °C for the 5 wt% compared to the 2.5 wt% and almost twice compared to the neat epoxy. This result is attributed to the intrinsic characteristics of the filler. Additionally, lower energy dissipation and a higher glass transition temperature were observed with the CQD amount. The novelty and importance are related to the fact that for more rigid matrices (corroborated with the literature), the mechanical properties did not change, because the polymer bridging mechanism was not present, in spite of the excellent CQD dispersion as well as the filler amount. On the other hand, thermal conductivity is directly related to particle size and dispersion.

Molecular dynamics simulations of several linear homopolymers: Assessment and comparison of shock properties

Understanding the behavior of polymers under shock loading is essential for their applications in car equipment, aircraft, space structure and plastic bonded explosives. Despite much effort, both experimentally and numerically over the last twenty years, there are specificities of the shock behavior of polymers that are still unclear. These include the relation of the shocked state to the dynamic glass transition and the deviation of the Hugoniot locus from the usual linear relation us=c+Sup, with us the shock velocity, c, the bulk sound velocity, up the particle velocity and S an empirical fitting parameter. To address these questions this work studies direct shock simulations in molecular dynamics (MD) of three different polymers, cis-1,4-polybutadiene, polystyrene and phenoxy resin. After thoroughly assessing that the polymer configurations created in this work are correct with respect to mass density, structure factor, chain dimensions and Hugoniot locus, this work focuses on two aspects of the behavior under shock loading. (i) The deviation of the Hugoniot locus from the linear relation us=c+Sup is related to a change in the relative contribution to the shock energy of the bonding and non-bonding potential energies as the shock strength increases. (ii) The shear stress relaxations behind the shock front are compared for the three polymers. It is found that the polymers with the highest glass transition temperature have the most slowly relaxing shear stress behind the shock front.

Triple-shape memory polybenzoxazine resins and their composites

Shape memory polymer (SMP) as a new type of smart material can be programmed into a temporary shape by external excitation. Benzoxazine is a novel thermosetting resin with excellent heat resistance, high glass transition temperature (Tg) and mechanical properties. Here, triple-shape memory polybenzoxazines with high Tg were obtained by copolymerization of phenol/polyetheramine with phenol/furanamine benzoxazines. Electrically driven composites were prepared using multi-walled carbon nanotubes, and the SMP electrically driven function was achieved by forming a complete and continuous conductive permeable network inside the composites, shape recovery can be completed in 15 s at 60v. Furthermore, at high temperatures the carbon residue rate is increased to 45 % at 800 °C, demonstrating the high performance of electrically driven shape memory polymer composites. The realization of the triple and electrically induced shape memory properties of shape memory polybenzoxazines broadens the way for their application in extreme high-temperature environments in aerospace and aviation.

Vinyl-Addition Homopolymeization of Norbornenes with Bromoalkyl Groups.

Vinyl-addition polynorbornenes are of great interest as versatile templates for the targeted design of polymer materials with desired properties. These polymers possess rigid and saturated backbones, which provide them with high thermal and chemical stability as well as high glass transition temperatures. Vinyl-addition polymers from norbornenes with bromoalkyl groups are widely used as precursors of anion exchange membranes; however, high-molecular-weight homopolymers from such monomers are often difficult to prepare. Herein, we report the systematic study of vinyl-addition polymerization of norbornenes with various bromoalkyl groups on Pd-catalysts bearing N-heterocyclic carbene ligands ((NHC)Pd-systems). Norbornenes with different lengths of hydrocarbon linker (one, two, and four CH2 groups) between the bicyclic norbornene moiety and the bromine atom were used as model monomers, while single- and three-component (NHC)Pd-systems were applied as catalysts. In vinyl-addition polymerization, the reactivity of the investigated monomers varied substantially. The relative reactivity of these monomers was assessed in copolymerization experiments, which showed that the closer the bromine is to the norbornene double-bond, the lower the monomer's reactivity. The most reactive monomer was the norbornene derivative with the largest substituent (with the longest linker). Tuning the catalyst's nature and the conditions of polymerization, we succeeded in synthesizing high-molecular-weight homopolymers from norbornenes with bromoalkyl groups (Mn up to 1.4 × 106). The basic physico-chemical properties of the prepared polymers were studied and considered together with the results of vinyl-addition polymerization.

Intermediate Polymer Relaxation Explains the Anomalous Rheology of Nanocomposites with Ultrasmall Attractive POSS Nanoparticles.

The rheological properties of entangled polymers loaded with very small, strongly attractive polyhedral oligomeric silsesquioxane (POSS) fillers differ from that of nanocomposites with larger fillers by (1) the shorter breadth of the entanglement plateau and (2) the relatively unchanged terminal viscosity with increasing POSS loading. Although such anomalous rheological properties can rewrite the property-processing map of materials (e.g., high glass transition temperature and low viscosity), their mechanism remains unclear. In this study, we report that polymer relaxations on intermediate time scales between α and entire-chain relaxation, so-called "slower processes", are responsible for this unusual rheological behavior of poly(2-vinylpyridine)/octa(aminophenyl)silsesquioxane (P2VP/OAPS) nanocomposites. To uncover the effects of entanglements on the nanocomposite dynamics, rheometry is used for variable matrix molecular weights. Results show a systematic change in the rheological response, which is independent of the molecular weight, and in turn, the presence of entanglements. This supports a physical interpretation that a slower process dominates the rheological response of the material at intermediate frequencies on length scales larger than the segment length or the OAPS diameter, while the underlying physical time scales associated with the entanglement relaxation remain unchanged. Such insights are anticipated to assist the future rational design of other highly attractive and ultrasmall nanoparticles that enable a fine-tuned rheological response of nanocomposites across multiple length scales.

Fabrication of High Impact-Resistant Polyimide Nanocomposites with Outstanding Thermomechanical Properties.

Neat polyimide films are known to be dense and rigid. They are therefore not suitable for use in membranes, sensors and sustainable energy storage applications. In this study, a novel technique has been used to simultaneously improve the porosity, rigidity, damping ability and impact resistance of polyimide membranes. It is demonstrated that dispersion of a small amount of polyaniline copolymer-modified clay of about 0.25-0.5 wt.% into the polyimide matrix resulted in an enhanced storage modulus while maintaining high damping ability and glass transition temperature, Tg. Novel polyimide/substituted polyaniline-copolymer-clay nanocomposite membranes containing poly(N-ethyl-aniline-co-aniline-2-sulfonic-acid)-modified-clay (SPNEAC) was successfully prepared and incorporated into the polyimide matrix to form modified clay/polyimide nanocomposites. UV-Vis analysis of the nanocomposite films shows that the optical transparency of the SPNEAC-PI nanocomposite membranes decreased with increasing SPNEAC concentration due to the high UV-Vis absorption of SPNEAC. Transmittance of about 3% was observed in the nanocomposite membrane containing 5 wt.% modified clay at 500 nm wavelength, which is significantly lower than that for the neat PI membrane of about 36%. The dispersion of SPNEAC containing a high concentration of clay (≥40 wt.% clay), in polyimide matrix, resulted in the attainment of a higher degree of imidization than was possible for the organoclay/polyimide nanocomposite. This behavior is believed to be due to the synergistic interaction between PI and SPNEAC. A correlation of the morphology and elastic modulus of the SPNEAC2/PI nanocomposites shows that at low loading of SPNEAC 2 ≤ 0.5 wt.%, the cross-sectional morphology of the composite is an open, spiky, weblike structure with a storage modulus of about 1 GPa, but it progressively evolves into densely packed microspheroids with storage moduli of ≥2 GPa at 10 wt.% SPNEAC2. The impact energy of SPNEAC/PI composites, calculated from the α-transition peak area, increased with increasing SPNEAC loading and were about 4 times that of neat PI at 10 wt.% SPNEAC.

Film Formation of Two‐Stage Acrylic Latexes: Toward Soft‐Core/Hard‐Shell Systems

AbstractControlling the colloidal structure of multiphase latex particles offers a route to significant improvements in the mechanical properties of dried films for use in coatings. However, there is often conflict between the morphology that leads to optimum mechanical properties and the morphology that ensures good film formation at reduced temperatures. In this work, the case of two‐stage latex particles in which the second‐stage polymer has a high glass transition temperature (Tg) is considered. First, a number of different core/shell‐like particles with different polymer compositions and particle structures are synthesized by seeded semi‐batch emulsion polymerization. Using these latexes, the importance of phase mixing, particle morphology, and polymer composition with respect to film formation behavior and mechanical performance is discussed. The results highlight that in multiphase latex systems, the film formation behavior is dictated by the interplay between various colloidal and polymeric features of the samples. It is shown that understanding these features offers a route to systems that can match the film formation properties of a low Tg latex, whilst also approaching the mechanical properties of a high Tg polymer.

Combining isosorbide and lignin-related benzoic acids for high-Tg polymethacrylates

The insertion of rigid aliphatic or aromatic building blocks in polymer structures is an efficient synthetic strategy towards high-Tg polymer materials. In the present work, we have functionalized isosorbide 5-methacrylate with various aromatic lignin-inspired esters to yield a series of isosorbide-2-aryl carboxylate-5-methacrylate monomers (ArIMAs) as single regioisomers. The selection of phenyl carboxylate side groups included benzoate, p-cyanobenzoate, meta/para-methoxybenzoates, and different vanillic acid esters. This afforded a range of seven bio-based monomers with different size, polarity, and substitutions. Polymerizations were carried out by conventional free radical initiation to obtain the corresponding high molecular-weight poly(aryl carboxylate isosorbide methacrylate)s (PArIMAs). The polymerizations were evaluated in different solvents, including toluene, EtOAc, γ-valerolactone, 2-MeTHF, and DMSO to identify the most suitable conditions. The polymers exhibited high glass transition temperatures in a broad range, from 80 to 168 °C, and were thermally stable up to 268 °C. Furthermore, dynamic rheology experiments indicated that the polymers were sufficiently stable for melt processing. The availability of the building blocks combined with the high stability of the polymers make these materials attractive for use as high-performance plastics and coatings.

Development of polyaniline/chitosan (PANI/CTS) and TiO2-PANI/CTS nanocomposites as anti-corrosion coatings: Synthesis and characterization

Polyaniline/chitosan (PANI/CTS) and TiO2-PANI/CTS nanocomposites were synthesized via in situ oxidative polymerization and characterized by different spectroscopies techniques. The interaction of PANI with the CTS structure and that of the TiO2 nanoparticles with the PANI/CTS copolymer matrix were confirmed by Fourier transform infrared spectroscopy (FT-IR). X-ray diffraction (XRD) analyses of the synthesized nanocomposites show a crystalline structure like their base materials (CTS, PANI and TiO2). The incorporation of PANI, CTS, and TiO2 in the formation of nanocomposites was confirmed by scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM-EDS). Thermogravimetric and differential scanning calorimetry (TGA and DSC) analyses indicate that the PANI/CTS and TiO2-PANI/CTS nanocomposites present greater resistance to thermal decomposition in relation to the CTS and PANI polymers, as well as the highest glass transition temperature (Tg). The anti-corrosion coatings were made by mixing the polymers and synthesized nanocomposites in an alkyd resin (AR) and deposited on 1018 carbon steel and evaluated in 3.5 wt% NaCl solution by linear polarization and electrochemical impedance spectroscopy (EIS) techniques. The best performance against corrosion was observed for the coating made from TiO2-PANI/CTS, since it shows the noblest values in potential, as well as the highest protection efficiencies, even after its immersion for 30 days, which is attributed to the high degree of cross-linking that the nanocomposite has, forming a dense protective film on the steel surface.

Rapid stress relaxation of high‐Tg conjugated polymeric thin films

AbstractConjugated polymers consist of complex backbone structures and side‐chain moieties to meet various optoelectronic and processing requirements. Recent work on conjugated polymers has been devoted to studying the mechanical properties and developing new conjugated polymers with low modulus and high‐crack onset strain, while the thin film mechanical stability under long‐term external tensile strain is less investigated. Here we performed direct mechanical stress relaxation tests for both free‐standing and thin film floated on water surface on both high‐Tg and low‐Tg conjugated polymers, as well as a reference nonconjugated sample, polystyrene. We measured thin films with a range of film thickness from 38 to 179 nm to study the temperature and thickness effect on thin film relaxation, where an apparent enthalpy–entropy compensation effect for glassy polymer PS and PM6 thin films was observed. We also compared relaxation times across three different conjugated polymers and showed that both crystalline morphology and higher modulus reduce the relaxation rate besides higher glass transition temperature. Our work provides insights into the mechanical creep behavior of conjugated polymers, which will have an impact on the future design of stable functional organic electronics.

Designs of ultra-HPHT Electrical Component Packages for Downhole and Geothermal Wellbore Logging Tool Integrations

Conventional dielectric sealing materials (PEEK, glass and glass-ceramic) used for sealing electrical feedthroughs, connectors, interconnectors and bulkheads in electronic packages can provide reliable downhole wellbore long-term logging tool service up to 150C or short-term logging service for greater than/equal 200C, due primarily to low glass transition temperature of the used sealing materials. This paper will demonstrate that the maximum allowable operating pressure and temperature could be from 20KSI to 100KSI and from 200C to 400C with Borosilicate and Bismuth-Boron-Silica (XTS) sealing glasses. Borosilicate glass sealed Inconel-Kovar/Kovar electronic housing could maintain reliability up to the maximum pressures of ~35KSI at 200C or 25KSI at 400C. Similarly, a Bismuth-Boron-Silica XTS glass sealed stainless steel electronic package housing could have a maximum operating pressure of ~100KSI at 150C or ~50KSI at 300C temperature. It has been found that high glass transition temperatures of (440-560)C for Borosilicate glass and (44010)C for Bismuth-Boron-Silicate (XTS) glass are key for making highly reliable ultra-HPHT electronic component packages. It is shown that the tetrahedral diamond-like microstructures of these sealing glasses are keys to ensure water-repelling properties to maintain sufficient electrical insulation resistance regardless of their use in water or moisture-rich wellbores. Moreover, compressive pin stress is found to be additional key for mitigate frequently observed glass seal cracks during logging tool field services.

Estimating Gas Sorption In Polymeric Membranes From The Molecular Structure: A Machine Learning Based Group Contribution Method For The Non-Equilibrium Lattice Fluid Model (ML-GC-NELF)

Since its inception, the non-equilibrium lattice fluid (NELF) model has become a vital tool in correlating and predicting the gas solubility behaviour in glassy polymeric membranes. But like its equilibrium variant, the NELF model is highly constrained by the availability of the pure polymer characteristic parameters, which are not always convenient to obtain as the need arises. In this study, we provide a proof-of-concept for building a machine learning-based group contribution method (ML-GC) for the Sanchez–Lacombe equation of state (EoS) pure polymer parameters. The ML-GC model was built using a modified version of the Marrero and Gani’s method, which incorporates machine learning regression into the GC parameterisation process. The final model was capable of reproducing the parameters of a randomly selected test set of polymers, with a diverse range of chemical structures. The resultant average AARD% of the predicted densities in this set is 5.59%, with no polymer exceeding 15%. Moreover, to test the model’s capabilities in estimating the parameters of high glass transition temperature polymers, we predicted a priori the characteristic parameters of 6 polyimides from the knowledge of their molecular structure. The ML-GC parameters were also incorporated into the NELF model to predict the infinite dilution solubility coefficients (S0) of some of these polymers and the results were validated against experimental data. Furthermore, the ML-GC-NELF model was also used for the first time to represent effectively the gas solubility isotherms in PIM-PI-SBI and PIM-PI-EA with relatively small magnitudes of the binary interaction parameters (kij). Despite the small data-set used herein, the model performance was satisfactory, however, as more data are being published in literature, the proposed ML-GC model has the potential of providing even more accurate predictions for a wider range of polymers, ultimately leading to lesser reliance on experimental data for modelling the gas sorption.

An optimized purple corn cob extract as an ingredient for the development of maize-based extrudates with novel characteristics

Purple corn cobs (PCC) are normally discarded although containing valuable components of potential application in the development of foods and ingredients. Optimum extraction conditions for PCC bioactive compounds were defined considering maximum antioxidant activity (AA), anthocyanins concentration (TAC), and total phenolic content (TPC). The optimized PCC extract (Opt-PCC) was added to a maize-based extruded formulation, and the obtained products were compared with a control sample without extract regarding their color, TPC, AA, physical properties, water adsorption isotherms, thermal transitions, and microstructure. Besides significantly modifying the color of extrudates, the addition of Opt-PCC increased their physical stability since higher glass transition temperatures were obtained when compared to the control at similar water contents. Differences in water sorption behavior could be attributed to the hygroscopicity of the compounds present in the extract. The incorporation of Opt-PCC increased TPC and AA of the extrudates by 14 and 4 times, respectively. The results confirmed a significant increase in the functional properties and physical stability of the extrudates with the addition of Opt-PCC, encouraging its use as a natural ingredient in the development of novel foods with improved characteristics.

Kraft lignin from Jackfruit waste as an adsorbent for the selective recovery of biobutanol from the Acetone-Butanol-Ethanol fermentation broth

Lignin, a naturally occurring aromatic heteropolymer can be used for the selective recovery of biobutanol from fermented broth due to the presence of functional groups such as hydroxyl and carbonyl. In the present work, kraft lignin was extracted from Jackfruit (Artocarpus heterophyllus Lam) waste (JFW), characterized and tested for the selective recovery of butanol from model solutions and Acetone-Butanol-Ethanol (ABE) fermented broth by adsorption-desorption. Fourier Transform Infra-Red (FTIR) spectra of the extracted kraft lignin displayed characteristic bands of the aromatic rings and monomeric functional groups. X-ray diffraction (XRD) analysis demonstrated lignin diffraction peaks at 25° and 32°. Jackfruit waste kraft lignin recorded a high thermal decomposition temperature (Td) and glass transition temperature (Tg) of 180 °C and 145 °C denoting high thermal stability. Isotherm and kinetics experiments disclosed a maximum butanol adsorption capacity (Qmax) and equilibrium time of 214.59 mg/g and 55 min of Jackfruit waste kraft lignin. Ex-situ recovery of biobutanol from the Acetone-Butanol-Ethanol fermented broth using Jackfruit waste kraft lignin recorded a 25% increase in butanol titre compared with the initial solvent concentration in the broth. The present results confirm the selective adsorption of butanol by the isolated Jackfruit waste kraft lignin from the Acetone-Butanol-Ethanol fermented broth. Using lignin as an adsorbent to selectively recover biobutanol will solve the long-standing bottleneck of Acetone-Butanol-Ethanol fermentation.

Sugars and Polyols of Natural Origin as Carriers for Solubility and Dissolution Enhancement.

Crystalline carriers such as dextrose, sucrose, galactose, mannitol, sorbitol, and isomalt have been reported to increase the solubility, and dissolution rates of poorly soluble drugs when employed as carriers in solid dispersions (SDs). However, synthetic polymers dominate the preparation of drugs: excipient SDs have been created in recent years, but these polymer-based SDs exhibit the major drawback of recrystallisation upon storage. Also, the use of high-molecular-weight polymers with increased chain lengths brings forth problems such as increased viscosity and unnecessary bulkiness in the resulting dosage form. An ideal SD carrier should be hydrophilic, non-hygroscopic, have high hydrogen-bonding propensity, have a high glass transition temperature (Tg), and be safe to use. This review discusses sugars and polyols as suitable carriers for SDs, as they possess several ideal characteristics. Recently, the use of low-molecular-weight excipients has gained much interest in developing SDs. However, there are limited options available for safe, low molecular excipients, which opens the door again for sugars and polyols. The major points of this review focus on the successes and failures of employing sugars and polyols in the preparation of SDs in the past, recent advances, and potential future applications for the solubility enhancement of poorly water-soluble drugs.

Synthesis of Functional Isosorbide-Based Polyesters and Polyamides by Passerini Three-Component Polymerization.

A new family of functional isosorbide-based polyesters and polyamides with high glass transition temperature are prepared via Passerini-three component polymerization (P-3CP). To optimize the P-3CP conditions, the influence of the polymerization solvent, temperature, feed ratio on the molar mass of final polymers are investigated. The higher molar mass (up to 10100 g/mol) and yield (>70%) are achieved under mild conditions (30 °C, standard atmosphere). Functional side groups, such as alkenyl, alkynyl and methyl ester, were introduced into polymer structure via P-3CP by using functional isocyanides. The obtained polyesters and polyamides are characterized by nuclear magnetic resonance (NMR) and infrared (IR) spectroscopies, differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). All polymers are thermal stable and amorphous with variable glass transition temperatures (Tg). The obtained polyester has Tg up to 87.5 °C, while the Tg of polyamides (ISPA-2) is detected to be 97.5 °C depending on the amide bonds in the polymer backbone and the benzene ring side groups. The cytotoxicity is investigated by the CCK-8 assay against mBMSC cells to confirm the biological safety. Overall, this novel strategy provides an efficient approach to produce functional isosorbide-based polyesters and polyamides, which are promising prospect for being applied to biodegradable materials.

Sulfone-bridged difuran polyesters

Oxidation of 5,5′-sulfanediyldi(furan-2-carboxylic acid) in acetic acid with aqueous hydrogen peroxide was used to prepare a new dicarboxylic monomer with a central sulfone group flanked by two biomass-derived furan rings. The new sulfone monomer was reacted with ethylene glycol, 1,3-propanediol, 1,4-butanediol, and 1,5-pentanediol to prepare new homopolyesters. Of these diols, 1,5-pentanediol yielded polyester with the most favorable properties in terms of processability and appearance. It could also be recycled back into the starting monomer under mild conditions. Using 1,5-pentanediol, a copolyester containing a 1:1 mixture of sulfone and sulfide difuran units was also prepared for testing alongside the corresponding sulfone difuran homopolyester. From measurements carried out on film samples of these two new materials, it was found that the new sulfone monomer will lead to polyester materials with high glass transition temperatures, high tensile stiffnesses, and low O2 permeability. The nature of the side reactions related to the difuran sulfone moiety under high temperatures remained unclear, as thermogravimetric analysis indicated relatively good stability characteristics and the monomer appeared relatively stable even at high temperatures.

Chemically recyclable polyolefin-like multiblock polymers.

Polyolefins are the most important and largest volume plastics produced. Unfortunately, the enormous use of plastics and lack of effective disposal or recycling options have created a plastic waste catastrophe. In this work, we report an approach to create chemically recyclable polyolefin-like materials with diverse mechanical properties through the construction of multiblock polymers from hard and soft oligomeric building blocks synthesized with ruthenium-mediated ring-opening metathesis polymerization of cyclooctenes. The multiblock polymers exhibit broad mechanical properties, spanning elastomers to plastomers to thermoplastics, while integrating a high melting transition temperature (Tm) and low glass transition temperature (Tg), making them suitable for use across diverse applications (Tm as high as 128°C and Tg as low as -60°C). After use, the different plastics can be combined and efficiently deconstructed back to the fundamental hard and soft building blocks for separation and repolymerization to realize a closed-loop recycling process.