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Polylactic acid (PLA) is a biodegradable and biocompatible polymer with versatile applications in packaging and medicine. It is derived from lactic acid and thus represents an eco-friendly option sourced from renewable raw materials. Despite its advantages, PLA exhibits few drawbacks, such as brittleness and relatively high melting and glass transition temperatures. However, these limitations can be addressed through copolymerization with other monomers like ε-caprolactone (ε-CL), resulting in a composite material with improved physical properties. This paper comprehensively reviews achievements in PLA–PCL copolymerization using organometallic catalysts, discussing scientific findings and various copolymer architectures obtained, including random or block configurations. It also demonstrates various sustainable catalysts for achieving the required microstructure under mild reaction conditions without the aid of any external initiator. [ABSTRACT FROM AUTHOR]

At present, phosphor-in-glass is regarded as a superior encapsulation material substituting for organic materials to resolve the poor thermal stability of WLEDs. However, the serious erosion reaction between commercial red phosphor and the glass matrix restricts the development and application of red phosphor-in-glass. In this work, a novel Sr4Al14O25:Li+,Mn4+ (SAO) red phosphor-in-glass film (PiGF) with precursor glass xB2O3–(85 − x)Bi2O3–5Al2O3–10CaO was prepared using a low-temperature sintering technique. Crystallization was observed in the precursor glass with 40% and 45% B2O3 content at 570 °C for 30 min, with the crystalline phase mainly being Bi4B2O9. The glass transition temperature gradually increases from 420 to 496 °C with an increase in B2O3 content from 40 to 60%. The DSC simulation and experimental results show that the degree of erosion of SAO phosphors decreases with an increase in B2O3 content from 50 to 60% and with an increase in the co-sintering temperature from 570 to 590 °C, while the glass surface smoothness of the PiGFs decreases with increasing B2O3 content. 55% B2O3 and 570 °C are the optimal parameters. The PL and PLE of the PiGFs show that the luminous intensity increases and then decreases with increasing B2O3 content, with 55% B2O3 also being the optimal value. The PiGF shows a quantum efficiency of 46.62%, and the luminous intensity maintains 85.1% of its initial intensity at 348 K. [ABSTRACT FROM AUTHOR]

We synthesized three poly(carbonate acetal) vitrimers (PCA-P, PCA-E, PCA-S) by condensing a waste polycarbonate-derived polyaldehyde (WPC-CHO) with pentaerythritol, erythritol, and D -sorbitol, using 0.5–4.0 mol% p-toluene sulfonic acid (pTSA) as a catalyst. Flexible PCA films emerged at pTSA concentrations ≥1 mol%, indicating a critical threshold of acid for effective condensation. The glass transition temperatures (Tg) of the films remained consistent across pTSA concentrations but varied based on the multi-alcohol structure, with Tg values of 178 °C for both PCA-P and PCA-S, and 142 °C for PCA-E, suggesting superior performance of pentaerythritol and D -sorbitol over erythritol as building blocks. Among these, the PCA-S series exhibited the best performance and utilized the least expensive starting materials, achieving the highest cost-performance index. The PCAs, featuring covalent adaptable polyacetal networks, facilitated thermal reprocessing through acetal metathesis. The second reprocessed PCA-P and PCA-S maintained similar thermal and mechanical properties to their original forms, demonstrating a closed-loop recycling. These polymers showed stability in THF/H2O (4/1) with 0.1–1.0 M H2SO4 at 25 °C, but can be degraded at 50 °C within 5 hours in both 0.5 M H2SO4 and HCl THF/H2O (4/1) solutions. NMR analysis of the degraded PCA-P confirmed the recovery of WPC-CHO and pentaerythritol. Furthermore, PCA-based carbon-fiber-reinforced plastics (CFRPs) were prepared, and the carbon fibers were successfully recovered after acid degradation without any loss to their structural or tensile integrity. [ABSTRACT FROM AUTHOR]

Phosphorus-containing flame retardants have attracted attention due to their outstanding flame retardancy, enhanced thermal stability, and limited toxic smoke emission. Bio-based phosphorus-containing flame retardants could be excellent options to impart environmental benefits, renewability, and sustainability to these materials. Lignin is an underutilized but abundant and sustainable material that can be used to serve this purpose. In the present work, a lignin-derived flame retardant was produced following the facile solvent-free polycondensation reaction of kraft lignin (KL) and phytic acid (PHA) at a low temperature in an aqueous system. The optimized conditions for this reaction were 1/0.4 mol/mol KL/PHA, pH 11, 20 °C, and 20 min. By utilizing advanced NMR (H, P, and HSQC), XPS, and FTIR techniques, the covalent bonding of the phosphorus of PHA with the oxygen of aliphatic and aromatic hydroxyl groups of KL was confirmed. C–P–O and P–O–P bonds provided high decomposition temperature (Tmax), high glass transition temperature (Tg), and char formation in the product. The presence of phosphorus atoms was observed on the combusted material by EDS mapping and EDX, illustrating the increase in the intensity of this element after combustion at 800 °C. The results of this work provided a new approach for preparing a fully bio-based flame-retardant with limited smoke density (i.e., a decrease from 34% for KL to 17.7% for modified KL) and a higher limiting oxygen index (i.e., an increase from 21.8% for KL to 26% for modified KL) following a green chemistry concept. [ABSTRACT FROM AUTHOR]

A series of linear block polymers and random polymers were synthesized by interfacial polycondensation using two bisphenols with similar structures, bisphenol S (BPS) and bisphenol A (BPA), and terephthaloyl chloride and isophthaloyl chloride. Random polymers and block polymers with the expected topology were structurally characterized by 1H NMR, FTIR, GPC, WAXD, and Raman spectroscopy. The results demonstrated that there was no significant difference in the thermal stability of the block and random polyarylates, which was due to the fact that the covalent bonds of the linked monomers did not change substantially, and the bond energies were the same. However, due to the alteration of the molecular sequence structure, the block polymer exhibited a lower glass transition temperature, a pronounced melting peak, and better solubility. With physical cross-linking points consisting of microcrystalline phases formed by the relatively regular molecular chain structure, the block polyarylates exhibited a higher modulus of elasticity than the random polyarylates. This illustrated that it is possible to prepare new functional polyarylates without changing the monomer composition, but only by manipulating the reaction process. [ABSTRACT FROM AUTHOR]

Amorphous solid phases can be represented by shallow basins in the potential energy hypersurface. Glasses formed by substances with prolific crystal polymorphism, such as nateglinide, an anti-diabetes drug, are susceptible to greater kinetical instability. Their energy landscape is characterized by deep pits in an accessible range, into which the supramolecular configuration can fall, when the amorphous solid relaxes to some crystalline polymorph. Alternative co-amorphization strategies are explored in this work to overcome the crystallization of nateglinide amorphous phases, namely by comparing two synthetic approaches, cryo-milling and quench-cooling, for a dual-drug system in combination with ranolazine. An alternative co-former, the essential amino-acid tryptophan, was also used for the synthesis of a cryo-milled nateglinide co-amorphous system. Enhanced kinetical stability for up to 8 months is achieved with both multicomponent systems. Their physico-chemical characterization in 3 molar ratios is accompanied by the study of their relaxation processes by broadband dielectric spectroscopy. Despite the higher glass transition temperatures obtained for the cryo-milled co-amorphous system with tryptophan, the co-amorphous salt system with ranolazine was found to have higher kinetical stability upon heating or ageing. [ABSTRACT FROM AUTHOR]

Random and block polyarylates were synthesized using bisphenol A (BPA), bisphenol fluorene (BHPF), terephthaloyl chloride (TPC), and isophthaloyl chloride (IPC) as raw materials. The synthesis strategies of one-step and stepwise interfacial polymerization methods were adopted. Both types of polyarylates exhibited similar solubility, with block polyarylates showing slightly broader solvent selectivity. The presence of large sterically hindered fluorene groups in BHPF monomers rendered both block and random polyarylates amorphous by restricting the movement of macromolecular segments. The polyarylates demonstrated excellent thermal stability (T5% = around 490 °C) and a high glass transition temperature (Tg > 210 °C). As the covalent bonds of the monomer linkage showed no significant difference, the thermal stability of both types of products was similar. The glass transition temperature increased with an increase in TPC and diefluorene monomer content. The tensile strengths of the random and block polyarylate films ranged from 45.77–69.89 MPa and 49.49–55.29 MPa, respectively, indicating the high tensile strength of the resulting polyarylates. While the block polyarylates did not show significant differences from the conventional properties of random polyarylates, the synthesis of block polyarylates in this study represents a novel attempt, further highlighting the significant influence of the large pendant group of the main chain on the ordered arrangement of molecular segments. [ABSTRACT FROM AUTHOR]

Laser-induced graphene (LIG) is a versatile form of graphene materials synthesized through direct laser writing (DLW) onto a carbon-rich precursor. Lignin is a promising natural precursor for LIG. However, the lack of understanding of the relationship between lignin chemistry and LIG properties limits the effective utilization of lignin. Herein, we aimed to understand the structural evolution of lignin into few-layer graphene during direct laser writing via the combined experimental investigation and reactive force field molecular dynamics (MD) simulation. Strong correlations were found between structural features of lignin and LIG characteristics, especially the sheet resistance (electrical conductivity) and defects in graphene domains. Specifically, higher molecular weight lignin demonstrated a superior propensity for generating the graphitic structure in the turbostratic matrix of LIG. This phenomenon led to better graphene quality in terms of morphological continuity, conductivity, and graphene domains. The glass transition temperature (Tg) of fractionated lignin was identified to have the strongest linear correlation with both sheet resistance and defect density in LIG. Additionally, the MD simulations shed light on the role of closely positioned carbon atoms in the initial substrate, highlighting their facilitative effect on the formation of large graphene domains. The proposed LIG formation pathway offers a new avenue for lignin biorefinery, facilitating efficient production of graphene materials from renewable resources. [ABSTRACT FROM AUTHOR]

Benzoxazines, renowned for their self-curing properties, high glass transition temperature, and exceptional thermal stability, have faced environmental and biotoxicity concerns despite their remarkable performance. Combining high-performance, ecofriendly and degradable benzoxazines remains a challenge. In this work, we synthesized an entirely bio-based benzoxazine resin, 2,6-bis(3-(furan-2-ylmethyl)-8-methoxy-2-phenyl-3,4-dihydro-2H-benzo[e][1,3]oxazin-6-yl)tetrahydro-[1,3]dioxino[5,4-d][1,3]dioxine (VE-BZ), from natural raw materials, including vanillin, erythritol, furfurylamine, and natural benzaldehyde. The presence of the bis(acetal) structure, furanic structure, and benzene ring-branched chain structure in the resin confers favorable adhesive strength, high carbon residue, self-extinguishing ability, and outstanding thermal stability to VE-BZ. Moreover, VE-BZ can undergo dual-site curing and complete degradation through the synergistic effects of acid and heat, enabling its reuse in benzoxazine synthesis. The acid used for both synthesis and degradation is bio-based citric acid, eliminating non-biobased catalysts or additives from the entire process. This approach embodies a comprehensive green chemistry closed-loop process. In essence, this research offers valuable perspectives on seamlessly combining exceptional performance with eco-friendly attributes in the realm of benzoxazine resin materials. [ABSTRACT FROM AUTHOR]

Migration of conventional petrochemical plasticizers can negatively affect the performance of plasticized products, human health and the environment and result in the reduction of petroleum resources. Thus, the development of bio-based plasticizers with migration resistance is very critical. In this study, two novel bio-based plasticizers with different structures derived from ricinoleic acid, i.e., epoxy acetylated benzyl ricinoleate (EABR) and epoxy acetyl terephthalate ricinoleate (EATPR), with good plasticizing effect and migration resistance were synthesized and characterized. The structure of EABR and EATPR was confirmed using FTIR and 1H NMR spectroscopies. The mechanical, thermal, and migration properties of the PVC samples plasticized with EABR and EATPR were extensively investigated, and the commercial plasticizer dioctyl terephthalate (DOTP) was used for comparison. The plasticized PVC samples with EABR and EATPR showed similar impact strength, elongation at break, and glass transition temperature (Tg) to DOTP-plasticized samples, indicating a good plasticizing effect on PVC. Furthermore, EABR and EATPR demonstrated superior performance in migration and volatility tests compared to DOTP. Besides, the plasticizing properties of the plasticized PVC were very sensitive to the structure of the plasticizer; EATPR, with a symmetric structure, showed better plasticization and plasticizing efficiency than EABR, with an asymmetric structure. In conclusion, the two bio-based plasticizers derived from ricinoleic acid showed attractive potential as alternatives to phthalate plasticizers, especially EATPR, with a larger symmetric molecular structure and higher aliphatic content. [ABSTRACT FROM AUTHOR]

As a green adhesive, lignin-based acrylate adhesives have a promising future in substitute commercial adhesives owing to their cost-effectiveness, and environmental friendliness. In this work, a green and convenient strategy for the fabrication of lignin-based acrylate adhesives was developed via the introduction of lauryl methacrylate with a low glass transition temperature (−62 °C) into the chemical structure of lignin to improve the compatibility, toughness, strength and wettability of lignin-based adhesives. With the introduction of lauryl methacrylate, the shear strength of the lignin-based adhesive reached 5.10 MPa, which is 114% higher than the traditional acrylate adhesive. Moreover, the lignin-based adhesive also exhibits excellent hydrophobicity and high shear strength after 12 h of immersion in water. This work not only provides a new strategy for the fabrication of economical, green, and sustainable lignin-based acrylate adhesives without the participation of organic solvents, but also achieves the value-added utilization of lignin. [ABSTRACT FROM AUTHOR]

Six dual active site ionic liquid catalysts were prepared by using triethylenediamine-grafted 1-bromotetradecane as a cation and coordinating with different organic anions. The structures and properties of the catalysts were characterized using Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR) spectroscopy, and thermogravimetric analysis (TGA). The synthesis of poly(isosorbide carbonates) (PICs) via the transesterification polycondensation of dimethyl carbonate (DMC) and isosorbide (ISB) catalyzed by a cation and anion was studied. A single factor experiment was used to investigate optimal process parameters. FT-IR, NMR, TGA, and differential scanning calorimetry (DSC) were adopted to characterize the structures and properties of PICs. The results showed that under the same process parameters, the catalyst using imidazole as an anion had the best catalytic performance. Under optimal process conditions, the conversion of ISB reached 98.82%, the weight average molecular weight of the PIC reached 28 840 g mol−1, and the glass transition temperature (Tg) of the PIC was 149 °C. [ABSTRACT FROM AUTHOR]

Starch derivatizations require harsh chemicals as solvents or catalysts, which can negate the green nature of starch-based materials. Often, these reaction systems require several hours to achieve moderate degrees of substitution (DS), drastically reduce molar mass and can result in undesired crosslinking compromising solubility. Here, we report an efficient and sustainable starch esterification with acetic anhydride (AA) and the optimization of the process avoiding initiators in terms of molar ratios, time, and temperature. Furthermore, chromatographic (HPSEC-MALS-dRI) and spectroscopic (FTIR, 1H NMR, 2D HSQC and HMBC, Solid State CP/MAS 13C NMR, TG-IR) tools were implemented to elucidate the chemical composition and structure of the resulting starch acetates and potential intermediate side reaction products over the course of the reaction. Different combinations of choline chloride (ChCl) with several hydrogen bond acceptors (urea, tartaric, malonic, and malic acids) were used as both chaotropic solvents and reaction promoters for starch acetylation. The reaction system comprising 1 : 1 molar ChCl : urea and AA showed good miscibility at 100 °C after 30 min, representing a seemingly homogeneous reaction system while better preserving starch molar mass. Side products emerging from solvent-reagent interactions, such as starch carbamate and acetylurea, were identified. Reaction optimization resulted in no side products, fast reaction rates (36 min), high DS (2.87) and starch loads (20 wt%), and increased reaction throughput and atom economy. Catalyst-free starch acetylation reduced hygroscopicity and increased glass transition and degradation temperatures (162 °C and 397 °C, respectively), while generally keeping a relatively higher molar mass (1.5–2.9 × 106 Da) than traditional starch acetates. [ABSTRACT FROM AUTHOR]

Hydrogels are promising materials, but because of their weak mechanical performance, further applications are limited. To enhance the strength of hydrogels, physical cross-linking was introduced by the use of hydrophobic unit diacetone acrylamide (DAAM) to form cross-linking points. The homopolymer of DAAM exhibited a high glass transition temperature above 80 °C, which was confirmed by DSC. The existence of the glassy and hydrophobic phases in the hydrogel was confirmed by XRD test results. The mechanical properties of the hydrogel were satisfactory, with a maximum tensile strength of 1.96 MPa, rapid recovery ability, satisfactory elasticity, and recyclability. A conductive hydrogel was prepared by introducing sodium ions, and it was used for human motion monitoring and is expected to be a promising material for flexible strain sensors. [ABSTRACT FROM AUTHOR]

An effective method of grafting functionalities onto lignin based on glycerol carbonate has been developed. This biobased grafting reagent reacts with lignin without generating co-products. Alkenyl groups were added to the glycerol carbonate moiety from 1,3-butadiene chemistry using the nickel-catalysed hydroalkoxylation reaction and the newly developed nickel-catalysed telomerisation reaction under solvent-free conditions. The high-atom economical reactions lead to three different sets of glycerol carbonate ethers with various chain lengths that can be separated from the catalyst to avoid lignin contamination with metals. Kraft, organosolv and soda lignins, without prior purification, were grafted via ether functions using these linkers in a clean and efficient procedure. The technical and modified lignins were characterised by NMR, IR and SEC, and their thermal properties were determined by DSC. The glass transition temperatures of the modified lignins are significantly reduced, opening up possibilities of shaping, for example, on hot presses. In addition, these modifications offer the possibility of inserting new reactive functions within the lignin, including unsaturations and alcohols, allowing a new range of lignin-based resins to be developed. [ABSTRACT FROM AUTHOR]

A diamine-bis(phenolate) chromium(III) complex, CrOH[L] ([L] = dimethylaminoethylamino-N,N-bis(2-methylene-4,6-tert-butylphenolate)), 2, in the presence of tetrabutylammonium hydroxide effectively copolymerizes CO2 and cyclohexene oxide (CHO) into a polycarbonate diol. The resultant low molar mass (6.3 kg mol−1) diol is used to initiate ring-opening polymerization of rac-lactide with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) giving ABA-type block copolymers with good molar mass control through varying rac-LA-to-diol loadings and with narrow dispersities. As the degree of rac-LA incorporation increases, the glass transition temperatures (Tg) are found to decrease, whereas decomposition temperatures (Td) increase. (Diphenylphosphonimido)triphenylphosphorane (Ph2P(O)NPPh3) was used as a neutral nucleophilic cocatalyst with 2, giving phosphorus-containing polycarbonates with an Mn value of 28.5 kg mol−1, a dispersity of 1.13, a Tg value of 110 °C and a Td value of over 300 °C. A related Cr(III) complex (4) having a methoxyethyl pendent group rather than a dimethylaminoethyl group was structurally characterized as a hydroxide-bridged dimer. [ABSTRACT FROM AUTHOR]

We report the fixation of carbon dioxide (CO2) into novel rubber polymers based on polycarbonate domains. Our strategy consisted in the atom-efficient terpolymerisation of CO2 with a long-alkyl-chain epoxide and an unsaturated epoxide to obtain polycarbonates with a glass transition temperature (Tg) below room temperature and with pendant double bonds along the backbone to enable peroxide-promoted cross-linking, thus generating an elastic rubber. First, a wide range of epoxides with long alkyl chains (C6-C12) were coupled with CO2 to give polycarbonates with high yields, using a binary catalytic system consisting of an aluminium amino-tris(phenolate) complex and bis(triphenylphosphoranylidene) ammonium chloride (PPNCl). The synthesised polycarbonates were characterised using FTIR and NMR spectroscopy to determine yields and selectivity, using DSC to measure the Tg, and using GPC to obtain the molecular weight distribution. Next, the terpolymerisation was carried out by including allyl glycidyl ether (AGE) in the reaction mixture together with a long-alkyl-chain epoxide and CO2. Almost complete epoxide conversions (81-100%) and extremely high selectivity (>97%) towards the desired polycarbonates were achieved, with only traces of the cyclic carbonate side-products. The obtained polycarbonates displayed a Tg < 0 °C and thus behave as low-viscosity fluids at room temperature. The pendant unsaturated groups introduced with the AGE monomers allowed cross-linking of the terpolymers with dicumyl peroxide, leading to an elastic rubber-like behaviour as witnessed by their markedly decreased solubility in gel-content tests and by their storage modulus, loss modulus, and Tg, which were determined by dynamic mechanical analysis (DMA). In summary, we have successfully demonstrated that the terpolymerisation of long-chain epoxides, AGE and CO2 yields polycarbonates that can be cross-linked to obtain elastic rubber properties, thus opening the prospects for a new range of applications for CO2-based green polycarbonates. [ABSTRACT FROM AUTHOR]

Herein, two new spiro-cored hole-transporting materials (HTMs), termed HT1 and HT2, are designed and synthesized, breaking the symmetry of the classical HTM, spiro-OMeTAD, by introducing benzo[d]imidazole with diverse electron characteristics of two nitrogen atoms to improve their hole-transporting properties. Both HT1 and HT2 exhibited excellent thermal stability with glass transition temperatures (Tg) of 162 and 197 °C, respectively, and good hole transport capability with hole mobilities of 8.26 × 10−5 and 1.08 × 10−4 cm2 V−1 s−1, respectively. When utilized in green perovskite quantum dot light-emitting diodes (Pe-QLEDs), the devices achieved low turn-on voltages of 3.0 and 2.8 V, maximum external quantum efficiency (EQEmax) of 7.6 and 6.7% and high maximum luminance of 45 056 and 46 382 cd m−2, respectively. The excellent hole-transporting properties and great device performance show that HT1 and HT2 are promising HTMs for Pe-QLEDs. [ABSTRACT FROM AUTHOR]

To fully exploit kraft lignin's potential in material applications, we need to achieve tight control over those key physicochemical lignin parameters that ultimately determine, and serve as proxy for, the properties of lignin-derived materials. Here, we show that fractionation combined with systematic (incremental) modification provides a powerful strategy to expand and controllably tailor lignin property space. In particular, the glass transition temperature (Tg) of a typical kraft lignin could be tuned over a remarkable and unprecedented 213 °C. Remarkably, for all fractions the Tg proved to be highly linearly correlated with the degree of derivatisation by allylation, offering such tight control over the Tg of the lignin and ultimately the ability to 'dial-in' this key property. Importantly, such control over this proxy parameter indeed translated well to lignin-based thiol–ene thermosetting films, whose Tgs thus covered a range from 2–124 °C. This proof of concept suggests this approach to be a powerful and generalisable one, allowing a biorefinery or downstream operation to consciously and reliably tailor lignins to predictable specifications which fit their desired application. [ABSTRACT FROM AUTHOR]

Polyelectrolytes with ultra-low glass transition temperatures (Tg) are still a rarity. Herein, we report a series of free-flowing lignin polyelectrolytes with ultra-low Tg in the range of −57–9 °C, namely, deep eutectic supramolecular lignin (DESL). The enabling key principle is to couple the eutectic strategy with supramolecular polymerization, bypassing the exclusive reliance on the large size and flexible cation/anion pairs for flowable polyelectrolytes. Following this principle, various sugars have been successfully integrated with lignosulfonic acid via multiple hydrogen bondings, allowing for bulk yet free-flowing supramolecular materials. These DESLs are processible, adaptive, and compatible to serve as macromolecular solvents and are distinct from traditional polyelectrolyte solutions or chemical modification derivatives. The robustness and versatility of our approach provide a fresh opportunity for booming polyelectrolyte utilization, opening access to a yet unknown fluidic material class. [ABSTRACT FROM AUTHOR]

Blending lignin with industrial degradable polyester is a sustainable and economically competitive strategy for biodegradable plastic production, but the miscibility of the composite remains a great challenge. In this study, the screened lignin with low molecular weight, uniform structure and rich hydroxyl groups was completely miscible with poly(butylene adipate-co-terephthalate) (PBAT). The low molecular weight of ethyl acetate dissolved lignin (EL) was critical for decreasing its glass transition temperature and steric hindrance, and the abundance of functional groups offered plenty of sites for forming strong intermolecular interactions between EL and PBAT. The intermolecular hydrogen bonds and π–π interactions of EL and PBAT promoted the dissociation of the lignin complex, thereby enhancing the plasticizing effect of PBAT on lignin. The PBAT/EL composite film with 50 wt% EL loading (P/EL50) displayed high tensile strength (24.7 MPa) and elongation at break (494.7%), being ahead of the currently reported PBAT composite films with high lignin addition. The yield strength increased threefold due to the rigid lignin structure and the intrinsic multiple noncovalent interactions. Moreover, compared to pure PBAT films, P/EL50 films exhibited a higher sensitivity of the mechanical performance to temperature and had a 22.9% cost reduction. [ABSTRACT FROM AUTHOR]

The development of repairable MOF-polymer hybrid materials will greatly extend their service life by repairing fractured parts on the spot; however, it is difficult for robust glassy polymers to self-heal below the glass transition temperature (Tg) as the polymer network is frozen. We herein report glassy polyMOF-RHP hybrid membranes by integrating lanthanide polyMOF (polyLnMOF) with randomly hyperbranched polymers (RHP) bearing a high density of hydrogen bonds. Since crystalline lanthanide MOFs act as multiconnected cross-linking agents and cross-link the interpenetrating polymer network, the obtained polyLnMOF-polymer membrane shows enhanced mechanical strength with a storage modulus of 3.09 GPa and a Tg up to 49 °C. Meanwhile, the high intersegment migration ability of the polyLnMOFpolymer network facilitates the exchange of hydrogen-bonded pairs even in the glassy state, leading to an instantaneous room-temperature self-healing ability. The polyLnMOF-polymer membranes inherit the ratiometric temperature-sensing behavior of pristine lanthanide MOFs, resulting in more processable temperature-sensing membranes. This work provides an appealing strategy for the design of mechanically robust, yet self-healing, MOF-polymer functional materials. [ABSTRACT FROM AUTHOR]

Hydroxyl groups of several industrial grade lignins are esterified by palladium-catalyzed hydroesterification reactions with CO and olefins, fatty esters or 1,3-butadiene. The reaction is efficient and salt-free and allows the introduction of aliphatic chains to lignin through the ester linkage. Technical and modified lignins are characterized by NMR, IR, and SEC and their thermal properties are evaluated by DSC. The esterified lignins show modified glass transition temperatures that depend on the substitution degree of the hydroxyl groups and on the nature of the aliphatic chains that have been introduced. The implementation of this catalysis also provides the possibility of inserting new reactive functionalities such as esters or unsaturations from abundant and/or biobased reactants. [ABSTRACT FROM AUTHOR]

Levoglucosan is a renewable chemical obtained in high yields from pyrolysis of cellulosic biomass, which offers rich functionality for synthetic modification and crosslinking. Here, we report the facile and scalable synthesis of a family of biobased networks from triallyl levoglucosan and multifunctional thiols via UV-initiated thiol–ene click chemistry. The multifunctional thiols utilized in this study can also be sourced from renewable feedstocks, leading to overall high bio-based content of the synthesized levoglucosan networks. The thermomechanical and hydrolytic degradation properties of the resultant networks are tailored based on the type and stoichiometric ratio of thiol crosslinker employed. The Young's modulus and glass transition temperature of levoglucosan-based networks are tunable over the wide ranges of 3.3 MPa to 14.5 MPa and −19.4 °C to 6.9 °C, respectively. The levoglucosan-based thermosets exhibit excellent thermal stability with Td,10% > 305 °C for all networks. The suitability of these resin formulations for extrusion-based 3D printing was illustrated using a UV-assisted direct ink write (DIW) system creating 3D printed parts with excellent fidelity. Hydrolytic degradation of these 3D printed parts via ester hydrolysis demonstrated that levoglucosan-based resins are excellent candidates for sustainable rapid prototyping and mass production applications. Overall, this work displays the utility of levoglucosan as a renewable platform chemical that enables access to tailored thermosets important in applications ranging from 3D printing to biomaterials. [ABSTRACT FROM AUTHOR]

It is of great significance for sustainable development to produce degradable, thiol–ene networks obtained from bio-based monomers using environment-friendly processes. Hence, we have prepared tunable and degradable thiol–ene crosslinked networks from renewable vanillin and multifunctional thiols. Vanillin was converted into an α,ω-diene monomer (1a) with degradable ester group via Williamson and Tishchenko reactions. UV-thermally induced thiol–ene click polymerizations between 1a and thiols with various functionalities were performed to prepare thiol–ene networks. 1,2-Ethanedithiol and 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane were also incorporated into the networks to further regulate their properties. The curing behaviours were studied by FT-IR and DSC to determine the optimal curing conditions. The thermomechanical, thermal and mechanical characteristics of the networks were investigated by DMA, DSC, TGA, and tensile strength tests to understand the influence of different crosslinkers on the material's properties. By varying the amount of co-monomer, the networks exhibited glass transition temperature, tensile strength, and elongations at break in the ranges of 14.5–43.3 °C, 2.6–24.8 MPa, and 29.1–510.2%, respectively. All the thiol–ene networks had good transparency with transmittance between 85 and 90% at 600 nm. Moreover, the networks could be degraded in mild alkaline aqueous solution owing to their inherent ester groups. [ABSTRACT FROM AUTHOR]

As the most abundant natural aromatic polymer on the Earth, lignin is expected to replace fossil resources for the preparation of high-performance thermosetting polymers. Numerous studies have been devoted to utilizing lignin through depolymerization and chemical modification; nevertheless, the green and facile valorization of lignin to high value products is still a challenge. Herein, we developed a straightforward approach to directly use lignin to prepare thermosetting polymers combining high performance and excellent degradability. In a green acetone–water–acetic acid component solvent system, lignin-based thermosets were facilely prepared via cross-linking reactions between lignin and glycidoxypropyltrimethoxysilane (KH560). The thermosets exhibited outstanding thermal and mechanical properties with a glass transition temperature of ∼214 °C, a tensile strength of ∼45 MPa and a Young's modulus of ∼2274 MPa, and these properties can be easily manipulated by adjusting the ratio of lignin to KH560. The presence of Si–O–C bonds and ester bonds in the network structure imparts excellent degradability to the thermosets in alkaline aqueous solution. This work provides a green and facile strategy to directly integrate lignin into cross-linked networks, which discloses a new idea for the valorization of lignin to value-added materials. [ABSTRACT FROM AUTHOR]

At temperatures supporting a glass transition in solid polyethylene terephthalate (PET), thermostable cutinases access the backbones of PET chains at the liquid–solid interface and hydrolyse ester bonds through endolytic and exolytic cuts. These lead to the production of three degradation intermediates [oligoethylene terephthalates (OETs), bis-hydroxyethyl terephthalate (BHET), and mono-hydroxyethyl terephthalate (MHET)] and two terminal degradation products [terephthalic acid (TPA) and ethylene glycol (EG)]. All five products are water-soluble to different degrees and diffuse away from PET to reach progressively higher concentrations in the surrounding solution, where they accumulate in proportion with the binding of cutinase to PET (through hydrophobic and cation–pi interactions). Importantly, however, the binding of cutinase to PET (which is essential for PET degradation) results in depletion of cutinase in solution, negatively impacting the conversion of degradation intermediates into terminal reaction products. The immediate and direct consequence of this is that the produced TPA and EG are contaminated by OET, BHET and MHET and, therefore, become unfit for recycling through re-condensation into PET. Here, we describe a 'two-enzyme' solution to the problem, consisting of a cocktail containing equimolar amounts of a PET-degrading enzyme [leaf-branch compost cutinase (LCC)] and a degradation intermediate-hydrolysing enzyme [Thermus thermophilus carboxylesterase (TTCE)]. The former produces OET, BHET, MHET, TPA and EG at PET's surface, while the latter works in solution to degrade the produced OET, BHET and MHET into TPA and EG. Through their synergy, the enzymes produce pure TPA and EG in yields that are 30–100% higher than those obtained with LCC alone. [ABSTRACT FROM AUTHOR]

Bio-recycling of plastic waste is a promising solution to plastic pollution. As one of the most abundant plastic wastes, polyethylene terephthalate (PET) can be degraded by carboxylic ester hydrolases (EC 3.1.1). Nevertheless, the biological PET hydrolysis efficiency is always limited by the low activity and poor thermostability of the enzymes. Herein, to address the above barriers, we rationally mutated the relevant sites of Thermobifida cellulosilytica cutinase 1 (ThcCut1) involved in substrate binding. The wider substrate-binding pockets after mutation could facilitate the accessibility of the enzyme to the substrate. Divalent metal-binding sites were further predicted and substituted with disulfide bonds, with the aim of effectively improving the thermostability of the mutant ThcCut1. Coupled with sequence alignment and structural dynamics analysis, the ThcCut1-D205C/E254C/Q93G variant with a melting temperature exceeding the glass transition temperature of recycled PET was constructed. After comprehensively screening the active and thermally stable mutation sites, the resulting ThcCut1-G63A/F210I/D205C/E254C/Q93G (ThcCut1-AICCG) variant exhibited high enzymatic activity at a high temperature (70 °C). As result, 96.2% of the post-consumer PET bottle particles (without energy-intensive melt-quenching pretreatment) can be successfully degraded after 96 h of hydrolysis using ThcCut1-AICCG, which was 87.5 times higher than that using the wild-type ThcCut1. This novel strategy for amino acid site analysis will facilitate the modification of homologous cutinases to improve the catalytic performance, and provide a reliable technical method for constructing a PET hydrolase modification platform. [ABSTRACT FROM AUTHOR]

Development of organic semiconducting polymers combining simple and scalable synthesis with high stability, solubility and hole mobility is in high demand. In this work, we report two novel D–π–A triphenylamine-based homopolymers having thiophene as a side π-spacer linked to either hexyl- or 4-fluorophenyldicyanovinyl electron-withdrawing groups. The homopolymers can be easily synthesized via oxidative polymerization at room temperature of the corresponding monomers in the presence of FeCl3 as an oxidant. The polymers possess a number of valuable properties for application in organic and hybrid optoelectronics, among which are high electrochemical and thermal stability (Td is up to 594 °C; coke yield up to 90%), good solubility (up to 90 g L−1 in chloroform), high glass transition temperature (up to 223 °C), efficient light absorption in the UV-Vis region, low-lying HOMO energy levels (ca. 5.36 eV) and sufficient hole mobility (up to 7 × 10−5 cm2 V−1 s−1) without any posttreatment in thin films. [ABSTRACT FROM AUTHOR]

Isotactic polybutene-1 (iPB-1) is of particular commercial interest due to its excellent mechanical performances. The form I polymorph is preferred in most industrial applications, while the form II is kinetically favored while melt processing. The slow II–I transition after melt processing dramatically hinders the iPB-1 applications. With new observations arising, the traditional solid–solid nucleation-controlled II–I transition mechanism encounters challenges. The role of the iPB-1 amorphous phase attracted many researchers' interests. In this work, an ultra-high molecular weight polyethylene (UHMWPE, labeled as PE4012) was melt-blended with iPB-1. The melt crystallization behaviors and the crystal structures of iPB-1 in the blends were investigated. It reveals that PE4012 addition inhibits the overall melt crystallization kinetics of iPB-1 in the blend due to the decreasing the spherulite nucleation density despite the observed radius spherulite growth being enhanced. The melting points, lamella thickness, the degree of crystallinity of forms I and II, the excess free energy of the fold surface σe, and the glass transition temperature Tg of form II iPB-1 all decrease with PE4012 weight proportion. The PE4012 component, mainly acting as an "obstacle" dispersed in the blend, disturbs the iPB-1 melt crystallization process with its initial start hindered, and interactions exist between the two components iPB-1 and PE4012 in the immiscible but to some extent compatible blend. Therefore, PE4012 is suitable for blending with iPB-1 and it may provide a good model system to look into the II–I transition process and its mechanism (will be discussed in the future as part 2). [ABSTRACT FROM AUTHOR]

Catalytic fast pyrolysis of biomass is a promising technology to generate biofuel blendstocks. This process generates a carbon-rich wastewater, which represents a loss of carbon that could be converted to co-products. Here, we explored the biological conversion of methyl phenols (cresols), a major component of biomass pyrolysis wastewater, into 2-methyl and 3-methyl muconic acids for use as polymer building blocks and plasticizers. We engineered Pseudomonas putida KT2440 to convert all three cresol isomers, o-, m-, and p-cresol, into their methyl muconic acid counterparts via the heterologous aromatic hydroxylase DmpKLMNOP from Pseudomonas putida CF600. We optimized conversion of cresols by expressing a heterologous (methyl)catechol dioxygenase ClcA from Rhodococcus opacus 1CP, followed by proof-of-concept fed-batch bioreactor cultivations. Methyl muconic acids and the hydrogenated methyl adipic acids were incorporated into nylons and plasticizers to evaluate potential performance advantages relative to existing materials. Methyl muconic acids in nylon-6,6 analogs substantially reduced melting and glass transition temperatures and enable post-polymerization modifications, and incorporating methyl adipic acid into nylon-6,6 analogs leads to a slightly reduced glass transition temperature and a 12% reduction in water permeability relative to nylon-6,6. When methyl diacids were incorporated into plasticizers for poly(vinyl chloride), they exhibit lower glass transition temperatures at the same mass loadings as phthalic acid and adipic acid-based plasticizers. The methyl diacids were also predicted to exhibit reduced health and environmental risks compared to phthalic acid. Overall, this study encompasses the selection of a target product from an exemplary waste stream to the demonstration of multiple industrially relevant performance advantages relative to petroleum-derived analogs and highlights the potential for biological waste stream valorization. [ABSTRACT FROM AUTHOR]

Cellulose-derived photocrosslinkable polycarbonates (PCs) with renewable citronellol pendant chains were synthesised through the polycondensation of Triol-citro, a recently developed levoglucosenone-based triol monomer, and dimethoxycarbonyl isosorbide. The polymer structures were unveiled through NMR spectroscopy and four repeating units were identified: three hydroxy-functional linear units (Ln, Lo and Lp) and one dendritic unit (Dq). The relative percentages of the repeating units, as well as the molecular weights of the corresponding polymers, can be finely tuned by varying the catalyst and reaction conditions (i.e., polycondensation temperature and monomer concentration). Thermal analyses demonstrated that the novel PCs exhibited low glass transition temperatures (Tg as low as −72 °C) and Td5% up to 159 °C. These hydroxy-functionalised PCs are not only fully biobased with a controlled extent of branching, but they also bear citronellol side chains that were successfully crosslinked via ultraviolet irradiation to further control the polymer properties. [ABSTRACT FROM AUTHOR]

A new kind of autocatalytic phthalonitrile monomer (PN) containing siloxane segments and secondary amino groups (TSOP) was synthesized from bisphenol compound and 4-nitrophthalonitrile using K2CO3 as a catalyst. Bisphenol was a reducing agent with a Schiff base containing secondary amine groups produced by the condensation reaction of 1,3-bis(3-amino-propyl)-1,1,3,3-tetra-methyl disiloxane and vanillin. The curing behaviors, kinetics, and thermal and thermomechanical characteristics of the TSOP monomer and its polymer (poly(TSOP)) were analyzed by torque rheometry, differential scanning calorimetry (DSC), Fourier transformation infrared spectroscopy (FTIR), thermogravity analysis (TGA), and dynamic thermal mechanical analysis (DMA), respectively. The non-isothermal curing kinetics results indicated that the cyano addition polymerization of the TSOP monomer was a self-catalytic reaction. The active hydrogen atoms from the secondary amino groups in the TSOP monomer could accelerate the crosslinking polymerization reaction of cyano groups, producing a decline in the curing temperature and a rise in the curing rate. Meanwhile, the TSOP monomer had a low melting temperature (77 °C) and a wide process window (110 °C) due to the introduction of flexible siloxane segments. The poly(TSOP) having phthalocyanine and a triazine ring exhibited a higher glass transition temperature (Tg) of 348 °C and good thermal stability. [ABSTRACT FROM AUTHOR]

In this study, microwave irradiation is employed for the phenolation of acid-insoluble Klason lignin. Microwave irradiation significantly reduces the reaction temperature (180 → 100 °C) and time (6 h → 10 min) without noticeable differences in the chemical structure of the phenolated lignin compared with the products prepared using a conventional heating method. As the reaction temperature increases (100 → 150 °C), lignin decomposition and crosslinking occur simultaneously, as did phenolation. Upon increasing the phenol-to-lignin ratio, the fragmentation of lignin is enhanced, while the crosslinking reaction is inhibited, leading to a decrease in the molecular weight and glass transition temperature of the phenolated lignin. Density functional theory is applied to elucidate the thermal and non-thermal effects of the electromagnetic field on the phenolation of Klason lignin. The solubility of Klason lignin in tetrahydrofuran and methanol is highly enhanced after phenolation, which allows for its adhesive application on glass, polyethylene naphthalate, and polyimide substrates. [ABSTRACT FROM AUTHOR]

The synthesis of self-healing and recyclable polymeric materials from renewable CO2 is of great importance in the fields of functional materials and sustainable chemistry. In this work, mechanically robust poly(urea-imine) (PUI) thermosets were prepared from CO2-sourced oligourea (OUa), terephthalaldehyde (TA) and tri(2-aminoethyl)amine (TAEA) through condensation between equimolar amino and aldehyde groups. The synthesized PUIs have satisfactory mechanical performance, seal-healing and recyclable properties as they contain cross-linked dynamic imine bonds and reversible hydrogen bonds. These properties can be adjusted by changing the ratio of TAEA to OUa, thus varying the chemical bonds and chain structure. The highest values for the mechanical properties tensile stress (10.2 MPa) and Young's modulus (79 MPa) were obtained in a PUI thermoset synthesized from a molar ratio of TAEA to OUa of 3 : 2 (OUa2-T3). In addition, this thermoset can be healed at 80 °C with a healing efficiency over 92% owing to the high reversibility of imine and hydrogen bonds and the flexibility of CO2-sourced OUa chains. Moreover, it can also be reprocessed and recycled by physical and/or chemical means without change in its chemical structure, glass transition temperature and original mechanical properties. Additionally, this PUI thermoset can be easily degraded into its original reagents OUa, TA and TAEA under acid conditions. Therefore, as novel sustainable materials, the PUI thermosets reported in this article have great potential to replace conventional non-degradable thermosets over a wide field. [ABSTRACT FROM AUTHOR]

As sandwiched hole transporting material (HTM) layers are in direct contact with up-coated perovskite layers and bottom electrodes in p–i–n structured perovskite solar cells (i-PSCs), the film quality of HTMs determines the morphological properties of the perovskite absorbent. To achieve excellent surface morphology of HTM films, two asymmetric structured HTMs featuring methoxytriphenylamine electron donors and imidazole cores, were successfully developed through two simple reactions of cyclization and Buchwald–Hartwig coupling. DI-TPA was designed by incorporating an extra methoxytriphenylamine unit in the C2 site of the imidazole core, whereas an isolated benzene ring was introduced for DI–Ar. The asymmetrical conformation contributes to high glass transition temperatures and supports thermal-stable amorphous properties in both HTM films. Compared with DI–Ar, DI-TPA featuring with an extended backbone realizes more effective capability of hole extraction arising from the enhanced intermolecular π–π interaction in the solid state. Consequently, the i-PSC with DI-TPA as a dopant-free HTM generates an encouraging power conversion efficiency of 16.54%, significantly exceeding that with DI-Ar (13.77%). It should be noted that the efficiency is shown to outperform that of commercial dopant-free HTM PEDOT:PSS (13.41%) under the same condition. This work offers a fundamental strategy by reinforcing electron donation to improve the hole mobility of asymmetric HTMs for dopant-free p–i–n structured inverted PSCs. [ABSTRACT FROM AUTHOR]

In the state-of-the-art lithium-ion battery, sustainability and safety have often been 'sacrificed' in favor of 'performance' and 'cost'. Regarding the electrolyte, volatile and flammable solvents and highly toxic fluorinated lithium salts need replacements. Thus, the first fluorine-free ternary polyethylene oxide-based polymer electrolyte plasticized with ionic liquid (IL) is hereby presented using the non-fluorinated 4,5-dicyano-1,2,3-triazolate (DCTA) as the anion for both conducting lithium salt and the IL plasticizer, respectively. Due to its low molecular weight, membranes with a high molar percentage of IL can be achieved, up to a PEO : LiDCTA : Pyr14DCTA ratio of 20 : 2 : 4, without crosslinking the polymer part. DCTA membranes feature glass transition temperatures (Tgs) and ionic conductivities in the same range as their bis(trifluoromethanesulfonyl)imide (TFSI) analogs and much higher transference numbers. The 20 : 2 : 4 membrane has a Tg of −55.4 °C and an ionic conductivity of 5.2 × 10 4 S cm−1 at 40 °C. LFP‖‖Li metal cells devoid of any critical raw materials and including this non-fluorinated TSPE were successfully cycled 300 times. [ABSTRACT FROM AUTHOR]

Acetalization of biomass-derived 5-hydroxymethyl furfural (HMF) with pentaerythritol produced a difuran (HPH) monomer in the presence of an acid catalyst. A recyclable polymer was then synthesized by Diels–Alder reaction of bismaleimide and the HMF-derived difuran (HPH). A polyurethane, produced from the Diels–Alder polymer has a higher glass transition temperature than a polyurethane, produced from ethylene glycol. The polyurethane, containing Diels–Alder polymer also has a self-healing ability. The Diels–Alder polymer could be hydrolyzed in acidic acetate buffer at 60 °C to produce the monomers for recycling. Each produced monomer was separated by solvent extraction, and the extracted monomers were recovered in different solvent fractions, such as aqueous, ethyl acetate, and acetone fractions. Techno economic analysis was used to assess the minimum selling price ($14.1 per kg) for the primary production of Diels–Alder polymer at a feed capacity of 400 tons per year. The economic viability of the primary recovery process for the most expensive recovered monomer, bismaleimide, was assessed by calculating the minimum selling price of the bismaleimide ($15.2 per kg). A circular closed-loop recycling production process for the Diels–Alder polymer was developed and this approach can produce the Diels–Alder polymer at $8.2 per kg when the feed capacity was 40 ktons per year. [ABSTRACT FROM AUTHOR]

High power conversion efficiency (PCE) and long-term stability are essential prerequisites for the commercialization of polymer solar cells (PSCs). Small-molecule acceptors (SMAs) are core materials that have led to recent, rapid increases in the PCEs of the PSCs. However, a critical limitation of the resulting PSCs is their poor long-term stability. Blend morphology degradation from rapid diffusion of SMAs with low glass transition temperatures (Tgs) is considered the main cause of the poor long-term stability of the PSCs. The recent emergence of oligomerized SMAs (OSMAs), composed of two or more repeating SMA units (i.e., dimerized and trimerized SMAs), has shown great promise in overcoming these challenges. This innovation in material design has enabled OSMA-based PSCs to reach impressive PCEs near 19% and exceptional long-term stability. In this review, we summarize the evolution of OSMAs, including their research background and recent progress in molecular design. In particular, we discuss the mechanisms for high PCE and stability of OSMA-based PSCs and suggest useful design guidelines for high-performance OSMAs. Furthermore, we reflect on the existing hurdles and future directions for OSMA materials towards achieving commercially viable PSCs with high PCEs and operational stabilities. [ABSTRACT FROM AUTHOR]

Iron(II) bis-pyrazolilpyridyl (bpp-R) complexes [Fe(bpp-R)2](X)2·solvent, R = substituent and X− = anion, can undergo a spin transition from high (S = 2, HS) to low spin (S = 0, LS), being spin crossover (SCO) in the solid state. The distortion of the octahedral coordination environment around the metal centre is governed by crystal packing, i.e. the intermolecular interactions among the substituent R of the bpp-R ligands, the anion X−, and the co-crystallized solvent, and this modulates the SCO behaviour. In this work, an innovative multivariate approach, through the combination of the chemometric tools Principal Component Analysis and Partial Least Squares regression, was applied on the coordination bond distances and angles and selected torsional angles of the available HS structures. The obtained results can efficiently model and rationalize the structural data distinguishing between SCO-active and HS-blocked complexes bearing different R groups, X− anions, and co-crystallized solvents and help predict the spin transition temperature T1/2. [ABSTRACT FROM AUTHOR]

High thermal stability is of pivotal significance for hole transport materials (HTMs) owing to thermal evaporation and device operation stability requirements. In this study, two new HTMs, namely FCzTPA and FCzDPNA, were developed by using easily accessible carbazole/dibenzo[b,d]furan derivatives. The rigid structures bring about excellent thermal stability, with a decomposition temperature (Td) of up to 400 °C and glass transition temperature (Tg) above 190 °C. Moreover, benefiting from the twisted spatial configuration and constituent units, they both exhibit suitable triplet energy levels (ET = 2.56, 2.74 eV). When hosting red phosphorescent organic light emitting diodes (PhOLEDs), the FCzTPA-based device shows a turn-on voltage (Von) of 3.4 V and the maximum external efficiency (EQEmax) of 18.61%, indicating that the synthetic compounds are potential building blocks for highly efficient OLEDs. [ABSTRACT FROM AUTHOR]

For a long period of time, while the glass transition temperature (Tg) had been mainly focused on in polymer science, the Tg values of small organic materials have been recognized to be important not only in medicines but also in a wide variety of organic optoelectronics in recent years. In this study, we report a useful and convenient "melt-blending" method to estimate organic semiconductor materials' Tg values, which are hard to observe when each material exists independently. We revealed that some cases reported incorrect Tg values. [ABSTRACT FROM AUTHOR]

For the first time, random copolymers of styrene (St) and 1,3-butadiene (Bd) (poly(Stn-r-Bdm), styrene butadiene rubber, SBR) were successfully prepared via solution reversible addition-fragmentation-transfer (RAFT) polymerization by employing dithio- and trithiocarbonate chain transfer agents (CTAs). The influence of various reaction parameters such as temperature and duration of polymerization, type of CTA, solvent and initiator, on molecular weight, molecular weight distribution (Mw/Mn) and the yield of the copolymers was investigated in detail. Determination of optimal reaction conditions allowed for the successful preparation of linear poly(Stn-r-Bdm) having Mn of up to 26 000 g mol−1 and Mw/Mn ≤ 1.6, with an isolated yield of up to 39 wt%. According to NMR the obtained copolymers were random and did not contain any styrene blocks (more than 5 units in sequence). The composition of poly(St-r-Bd) was found to be nearly independent of reaction conditions and consisted of 19.6–24.0, 15.0–15.5 and 60.5–64.5 wt% of styrene, (1,2)-Bd and (1,4)-Bd units, respectively. The glass transition temperature (Tg) of the copolymers (measured via DSC) varied between −55 and −62 °C, while Tonset (measured via TGA) ranged between 385 and 390 °C. The optimized synthetic method for production of poly(Stn-r-Bdm) copolymers was then extended to produce various poly[Xn-b-(Stm-r-Bdk)] block copolymers, where X represents different methacrylic or styrenic monomeric units. The molecular weight of the poly[Xn-b-(Stm-r-Bdk)] block copolymers was mainly dependent on the molar mass of the starting poly(Xn) macro-CTA and reached as high as 72 000 g mol−1, with the SBR segment varying between 11 800 and 39 600 g mol−1. These materials, believed to be the first of their kind reported in the literature, show clear evidence of nanostructure formation via AFM and promise unique and attractive combinations of stiffness, toughness, thermomechanical performance and chemical reactivity. This work opens up new avenues for the synthesis of novel copolymers with exceptional levels of structural control, thus providing additional tools to the polymer research community as far as the design and creation of materials with new and useful properties is concerned. [ABSTRACT FROM AUTHOR]