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In this study, the aliphatic N,N‐bisguanidine zinc complex [Zn(DMEG2ch)2](OTf)2 ⋅ THF is introduced as a promising candidate for the chemical recycling of (bio) polyesters. This catalyst is highly active in the ring‐opening polymerization (ROP) of lactide (LA) and ϵ‐caprolactone (CL). The combination of polymerization and depolymerization activity creates new pathways towards a sustainable circular economy. The catalytic activity of [Zn(DMEG2ch)2](OTf)2 ⋅ THF for the chemical recycling of polylactide (PLA) via alcoholysis was investigated by detailed kinetic and thermodynamic studies. It is shown that various high value‐added alkyl lactates can be obtained efficiently under mild reaction conditions. Catalyst recycling was successfully tested using ethanol for the degradation of PLA. In addition, LA can be recovered directly from PLA, enabling either open‐ or closed‐loop recycling. Selective PLA degradation from mixtures with polyethylene terephthalate (PET) and polymer blends are presented. For the first time, a cascade recycling reaction of a PLA/polycaprolactone (PCL) blend is tested with a zinc‐based bisguanidine catalyst, whereby PLA is degraded selectively at first and subsequent modification of the reaction conditions leads to efficient degradation of the remaining PCL. The highly active, universally applicable benign zinc catalyst allows the implementation of a circular plastics economy and thus the reduction of plastic pollution in the environment. [ABSTRACT FROM AUTHOR]

In laboratory conditions, composite sutures based on polylactide (PLA) containing chitin nanofibrils modified with polyethylene glycol (CN‐PEG) and poviargol (silver nanoparticles stabilized with poly(N‐vinylpyrrolidone)) were obtained, studied, and used as a prototype. Surgical sutures threads with the addition of CN‐PEG have stable mechanical properties both in air and in a buffer simulating the environment of a living organism. The yield strength of oriented threads decreased by an average of 15%, whereas for non‐oriented threads the decrease was 3–4 times. The strength values in simple units of unfilled PLA, PLA containing 5 wt % CN‐PEG, and PLA with 1 wt % Poviargol were on average 50% higher than the national standard 31620‐2012. The results of in vivo experiments on albino rats (cross‐linking skin and muscle tissue in the linea alba area) showed that composite sutures are best for suturing muscle tissue, whereas unfilled PLA sutures are more suitable for suturing skin. When suturing muscle tissue, suturing with composite sutures increased the number of collagen fibers of different diameters. [ABSTRACT FROM AUTHOR]

In this work, polylactide (PLA) was loaded with wood flour (WF) or hazelnut shells (HSs) (10% and 20% of fillers). The matrix and biocomposites were fully characterized from a mechanical and rheological point of view to test their processability and mechanical performance. Compost burial degradation test (30 days), with or without a prior photo‐oxidation step, assessed their biodegradability after an outdoor application, and was monitored by weight loss (WL). The viscosity of the biocomposites was lower than that of the matrix and this unusual result can be attributed to a limited adhesion between the PLA and fillers. Both fillers increased the elastic modulus but decreased the tensile strength and elongation at break. As for the weathering, the degradation of PLA was mostly due to hydrolytic chain scission due to the presence of humidity. Resistance of PLA to UV irradiation improved in presence of both the two fillers. Their lignocellulosic nature was responsible for this behavior. Both fillers induced a high resistance and lower degradation in compost: WL percentages of virgin PLA was about 26%, biocomposites with 20% of WF or HS showed WL of about 10% and 14%, respectively. Photo‐oxidation (36 h with condensation cycle) increased the compost degradation rate of both biocomposites and WL of PLA with 20% of WF or HS were about 15% and 21%, respectively, after 30 days. Highlights: Poor adhesion between the matrix and fillers reduced the biocomposites viscosity.Fillers increased the elastic modulus but decreased the properties at break.Both fillers improved the resistance of PLA to UV irradiation.Biocomposites showed a lower susceptibility to compost degradation than PLA.Photo‐oxidation increased the compost degradation rate of biocomposites. [ABSTRACT FROM AUTHOR]

Over the past years, poly(lactic acid) or polylactide (PLA) is commonly researched as a possible replacement for traditional fossil‐based polymers because of its compostability, biocompatibility, and high mechanical properties. PLA has a variety of applications in packaging, biomedical, and structural. However, PLA has limitations, such as high brittleness, low thermal stability, and a slow crystallization rate, which limits the wide range of applications. To overcome these limitations, the literature reports that blending PLA with other polymers, such as poly(ε‐caprolactone) (PCL), is an economically viable approach. Although blending PLA with PCL is considered a feasible approach, the blend system still suffers from immiscibility, depending on the blend composition. This review aims to highlight recent developments from 2014 to date on the processing of PLA/PCL blends, including their composites, with a primary focus on morphological characteristics and mechanical and thermal properties, including their potential applications in various sectors. [ABSTRACT FROM AUTHOR]

Within this research semi‐crystalline polylactide and composites with 50 wt.% native potato starch were compounded and injection molded. The material was mechanically characterized by tensile, three‐point bending, and Charpy impact tests. These tests were carried out in the freshly molded state and after 332 and 792 h of storage at accelerated temperature or humidity. The respective activation energy was calculated by applying the Flynn‐Wall‐Ozawa method. The focus of the study was to investigate the correlation between the activation energy and the related mechanical and thermal properties. The results showed that the addition of native potato starch as a filler prevents the decrease in activation energy over the course of the experiments. Thus, the PLA/starch composite is more resistant to the two aging conditions than the pure PLA. When considering the mechanical properties, the pure PLA showed a large deviation of results compared to the initial value in a range of +63.88% to −33.96% with regard to the respective aging conditions, whereas the PLA/starch composite properties nearly always remained at the initial values. Through the investigation of the mechanical and thermal properties, it was shown that the steady activation energies are consistent with the mechanical properties, as these have shown only a small deviation of the mechanical properties during the duration of experiments for the PLA/starch composite. [ABSTRACT FROM AUTHOR]

The structure and properties of incompatible polylactide (PLA)/polyamide elastomer (PAE) blends were tailored by a chain extender specifically the styrene–glycidyl acrylate copolymer Joncryl ADR4368 (ADR). Various PLA/PAE/ADR blends with different compositions were prepared by melt blending, and their morphology, crystallization behavior, and mechanical and the shape memory properties were systematically investigated. The results showed a uniform dispersion of PAE particles in the PLA matrix for the PLA blends with a reduction in particle size upon the addition of ADR. The crystallization of PLA was retarded, which was confirmed by a decrease in the melt crystallization temperature and an increase in cold crystallization temperature in the PLA/PAE/ADR blends. Rheological analysis showed an improvement in the melt elasticity of the PLA/PAE binary blend due to the presence of ADR, possibly attributed to the formation of long‐chain‐branched copolymers at the interface. Notably, the PLA/PAE/ADR blend exhibited superior toughness, featuring an elongation at break of 288% and a notched impact strength of 37 kJ·m−2, along with a high shape memory fixation rate and recovery rate when the ADR content was 1 wt%. Furthermore, the underlying toughening mechanism was elucidated. This work may offer an industrially scalable relevant model to fabricate high‐performance PLA materials. [ABSTRACT FROM AUTHOR]

Polylactide (PLA)-based reversible/dynamic polymer networks were synthesized by coupling 4-arm PLA stars containing reversible tetraphenylethane (TPE) groups in the core using diisocyanate. Star-shaped PLAs with molecular weights of 3200 and 6400 g/mol were obtained by the original method involving UV coupling of linear PLAs containing benzophenone moieties in the chain middle. The efficient formation of networks with gel content close to 100% was confirmed by FTIR spectroscopy. Networks with different densities of reversible groups exhibited tensile strength in the range of 35-50 MPa. Their reversible character was demonstrated by stress relaxation measurements performed at different temperatures (120-150°C). The prepared networks were capable of very fast stress relaxation due to radical exchange reactions between TPE groups placed in crosslinks, in contrast to a reference network without TPE groups. It was shown in the repairing experiment that networks were capable of processing. [ABSTRACT FROM AUTHOR]

ABA types triblock copolymers, specifically poly(L‐lactide)‐co‐poly(ethylene glycol)‐co‐poly(L‐lactide) (PLLA‐PEG‐PLLA) and poly(D‐lactide)‐co‐poly(ethylene glycol)‐co‐poly(D‐lactide) (PDLA‐PEG‐PDLA), are employed for stereocomplexes (SCs) formation. These SCs are subsequently utilized as axles, in conjunction with various cyclodextrins (CDs) as ring moieties to create pseudo‐polyrotaxane (PPRX). The authors referred to this new construct as "SC PPRX", to distinguish it from the earlier study, denoted as "PPRX SC", which primarily focuses on SC within the PPRX. When attempting to form PPRXs in aqueous solutions, the authors encountered challenges related to the inclusion of CDs due to the robust presence of the SC structure. However, by using mixed solvents, such as water/acetone (10/1, v/v), a partial relaxation of the SC structure is observed. This allows for the successful inclusion of CDs, thereby facilitating the PPRX formation. These observations highlight the significance of axle–axle interaction, which, in this case, prevailed over axle–ring interactions in determining the outcome of the formation process. The authors propose the term, 'SC pseudo‐capping effect' to describe this unique phenomenon, underscoring the role of interactions among polymer chains, including polymer–polymer and axle–axle interactions, in shaping the architecture of rotaxanes. This study thus unveils a novel dimension of polymer‐polymer interactions within the realm of rotaxane. [ABSTRACT FROM AUTHOR]

Fused deposition modeling (FDM) has been a commonly used technique in the fabrication of geometrically complex biodegradable scaffolds for bone tissue engineering. Generally, either individual polylactide (PLA) or its combination with calcium phosphates or bioglass has been employed to design scaffolds through the principles of FDM. In this study, FDM protocol has been employed to design 3D printed PLA/zirconia‐toughened alumina (ZTA). A series of PLA/ZTA combinations have been attempted to determine the feasibility of the resultant in filament extrusion and their subsequent capacity to obtain a stable 3D printed component. A maximum of 80 wt.% PLA and 20 wt.% ZTA has been determined as an optimum combination to yield a stable 3D structure beyond which an enhanced ZTA content in the PLA matrix yielded a fragile filament that lacked effectiveness in 3D printing. 5 and 10 wt.% of ZTA addition in the PLA matrix produced a better 3D design that reasonably displayed good mechanical properties. Depending on the ceramic content, a homogeneous dispersion of the constituent elements representative of ZTA has been determined throughout the PLA matrix. Simulation studies through finite element analysis (FEA) exhibited good corroboration with the test results obtained from the mechanical studies. [ABSTRACT FROM AUTHOR]

Blending poly(butylene succinate) (PBS) with polylactide (PLLA) has proven effective in improving heat resistance of PLLA fibers. Unfortunately, it remains challenging to maintain good spinnability for PLLA/PBS blends with high content of PBS with which further improved heat resistance could be anticipated. In this study, reactive melt‐extrusion was devised to in‐situ generate PLLA‐PBS copolymers by introducing zinc acetate as a transesterification catalyst into PLLA/PBS blends. The compatibility between the PLLA and PBS phases was greatly improved by the formation of PLLA‐PBS copolymers, resulting in excellent melt‐spinnability even for the PLLA/PBS blends with high PBS content up to 20 wt%. In addition, an increase in crystallinity of PLLA was achieved in PLLA/PBS blend fibers, thanks to the enhanced compatibility. More importantly, the presence of PBS nuclei retarded the molecular orientation of the amorphous PLLA phase, consistent with the effective results from the relaxation heat‐setting treatment. These led to an exceptionally improved heat resistance of the PLLA/PBS blend fibers. As an encouraging result, the boiling water shrinkage was significantly reduced from ca. 20% for neat PLLA fibers to 3.7% for the PLLA/PBS blend fibers with 20 wt% PBS content. These findings may open up a facile and effective route to develop PLLA/PBS blend fibers showing sound spinnability, greatly improved heat resistance and softness. [ABSTRACT FROM AUTHOR]

A series of polylactide (PLA)/polycaprolactone‐based polyurethane (PCLU) blends were prepared by reactive blending of PLA with polycaprolactone diol (PCL diol) and hexamethylene diisocyanate (HDI). The reaction mechanism, compatibility, crystallization behavior and the mechanical properties of the PLA/PCLU blends were investigated. It was demonstrated that the hydroxyl group of PCL diol or PLA could react with the isocyanate (NCO) group of HDI to form PCLU or PLA‐co‐PCLU in situ, thereby improving the interfacial compatibility between PLA and PCLU phases. Phase‐separated morphology with the PCLU dispersed in the PLA matrix was observed for the PLA blends with an obscure interphase. The thermal and cold crystallization ability of PLA were retarded. PLA/PCLU blend showed higher impact strength and elongation at break compared with pure PLA. Specifically, at a 40 wt% feed ratio of PCL diol, the impact strength reached an impressive 28 kJ m−2. Notably, the shape memory performance of the blend showed a substantial improvement, achieving a remarkable shape recovery rate of 96.3% at the same 40 wt% PCL diol feed ratio. The mechanisms governing both toughening and shape memory enhancement in the blend were thoroughly elucidated. [ABSTRACT FROM AUTHOR]

The aim of this study was to integrate an antibacterial agent into implant materials to prevent infection and to investigate the aging behavior of the plastics in physiological solution as a function of filler type and proportion as well as of the process parameters. The active ingredient that is incorporated into the polymer during compounding should remain effective in the body over a long period of time. With varied melt processing conditions, composites made of a biodegradable polylactide (PLA) were mixed with tricalcium phosphate (TCP) and zinc oxide (ZnO) as an antibacterial agent. Hydroxyapatite (HAP) and zinc oxide were incorporated into a non‐degradable polyetheretherketone (PEEK). The material properties of the composites were characterised and investigated with regard to their in vitro behaviour. The investigations were carried out with gel permeation chromatography (GPC), differential scanning calorimetry (DSC), tensile tests, recording of the mass change during storage and colony forming units test (CFU). Over the investigated ageing period of 9 months in phosphate buffered saline (PBS) at 37 °C the composites showed antibacterial efficacy against Escherichia coli. [ABSTRACT FROM AUTHOR]

Long‐chain branched polylactides (PLA‐LCB) with high melt strength were prepared through a melting reaction using Trigonox301 or dicumyl peroxide (DCP). During this reaction, random chain scissions, branching reactions, and cross‐linking reactions took place, as confirmed by the torque‐time rheograms and gel permeation chromatography profiles. It is evident that the random chain scissions are more prominent in PLA‐LCBD compared to PLA‐LCBT. The rheological characterization further elucidated the formation of LCB architecture. With an increase in the content of Trigonox301 or DCP, both branch‐on‐branch architecture and cross‐linked architecture were observed. The preference for branch‐on‐branch architectures was found to be higher in PLA‐LCBT as compared to PLA‐LCBD. Additionally, the presence of gel fraction was more easily detectable in PLA‐LCBD samples, indicating a higher likelihood of cross‐linking reactions in these samples. The emergence of new peaks at the positions of 1.82 and 1.47 ppm establishes a solid theoretical foundation for the potential reaction mechanism. One possible explanation proposed is that the reaction rate of free radicals originating from PLA‐LCBD samples is significantly higher than the diffusion rate of macromolecular free radicals. Consequently, the occurrence of a free radical chain transfer reaction is limited to a very small region, resulting in the formation of a cross‐linked structure. While the free radicals that are produced by the cyclic peroxide actively contribute to the graft reaction, thereby promoting the formation of the LCB structure with a micro‐crosslinking component. [ABSTRACT FROM AUTHOR]

Polylactide (PLA) is the most widely utilized biopolymer in medicine. However, chronic inflammation and excessive fibrosis resulting from its degradation remain significant obstacles to extended clinical use. Immune cell activation has been correlated to the acidity of breakdown products, yet methods to neutralize the pH have not significantly reduced adverse responses. Using a bioenergetic model, delayed cellular changes were observed that are not apparent in the short‐term. Amorphous and semi‐crystalline PLA degradation products, including monomeric l‐lactic acid, mechanistically remodel metabolism in cells leading to a reactive immune microenvironment characterized by elevated proinflammatory cytokines. Selective inhibition of metabolic reprogramming and altered bioenergetics both reduce these undesirable high cytokine levels and stimulate anti‐inflammatory signals. The results present a new biocompatibility paradigm by identifying metabolism as a target for immunomodulation to increase tolerance to biomaterials, ensuring safe clinical application of PLA‐based implants for soft‐ and hard‐tissue regeneration, and advancing nanomedicine and drug delivery. [ABSTRACT FROM AUTHOR]

Surface modification of polylactide films was performed using a dielectric barrier discharge (DBD) with the aim of increasing proliferative activity of human fibroblasts on these films. It has been shown that during the plasma treatment of the polylactide film, nonlinear processes occur depending on the processing time. The effect of the dielectric barrier discharge on the modification of polylactide films was evaluated using IR spectroscopy, AFM, XPS, TSDC, and the wetting angle of the surface. The optimal processing time in DBD of polylactide films is 3 min for this installation, the proliferative activity increases by 10% compared to the original film. This treatment time provides an increased concentration of oxygen‐containing groups, optimal relief, and free surface energy of 55 mJ/m2 on the surface. Highlights: The biocompatibility of the polylactide film was improved by 10% used DBD.The optimal processing time of PLA films in DBD is 3 min.The functionalization of the polylactide surface occurs non‐linearly. [ABSTRACT FROM AUTHOR]

Starch is an essential biopolymer in biofuel production and a sizing agent in the paper and textile industries. However, native starch is unsuitable for most applications due to brittleness, inferior mechanical and thermal properties, and poor processability. In this regard, a series of modified starch‐based biopolymer composites were prepared by extrusion to produce composites with enhanced properties for enlarged applications. Unlike other studies, the developed thermoplastic starch (TPS) in this work was produced by gelatinizing starch with glycerol and poly(butylene succinate) (PBS) to induce both plasticization and compatibilization. The resultant TPS was blended with diverse organoclays and polylactide (PLA) via a twin‐screw extruder to obtain TPS/PLA/organoclay composites. The ensuing composites were studied for thermal and morphology properties using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Results showed that the organoclay loading highly influenced the mechanical and thermal properties of the TPS/PLA composites by enhancing the thermal stability and stiffness of the blends. More importantly, incorporating a small amount of organoclay into PLA enhanced its compatibility with TPS, as depicted in morphological studies. The enhanced crystallization and compatibilization of the blends resulted in enhanced mechanical properties of eco‐friendly composite materials for sustainable packaging applications. [ABSTRACT FROM AUTHOR]

Composite threads based on polylactide (PLA) containing up to 20 wt% carbon nanofibers (CNF) were produced using melt technology. The formation of a percolation cluster was studied in composite filaments with various morphologies (non‐oriented, subjected to isothermal crystallization, and oriented by six times). By adding 20 wt% CNF, a specific resistance of 100 Ohm m was achieved in the PLA filament. With orientation stretching, the specific resistance was 107 Ohm m, regardless of the CNF concentration. The scanning electron microscopy study showed poor adhesion between PLA and CNF. Threads containing 1 wt% CNF demonstrated stable conductive characteristics under dynamic loading for 24 h (50% of their breaking load). Studies of the creep of composite fibers have shown that small amounts of CNFs promote the sliding of polymer fibrils. In vivo tests showed that the addition of 5 wt% CNF led to an increase in the rate of bioresorption of PLA filaments. Additionally, the conductive properties were maintained for 12 months after implantation. The prepared filaments can be used in flexible electronics for biomedical applications. [ABSTRACT FROM AUTHOR]

As an eco‐friendly material, PLA was a desirable alternative to polyethylene and polypropylene films due to its biodegradability. The preferable melt strength of PLA‐based materials was a key factor in ensuring its processing using extrusion blow. This paper focuses on the influence of interchain force and/or chain entanglement on the melt strength and ductility of PLA‐based materials in recent years. In addition, the preparation of PLA‐based materials via physical blending or reactive processing was also summarized. The blending of PLA with a flexible heteropolymer, driven by the interchain force and/or chain entanglements, were characterized as a practicable method for toughening PLA‐based materials. Also, the restructuring of PLA chains, by branching based on chain entanglement, was suitable for increasing chain entanglements in PLA matrix, yielding satisfactory melt strength and ductility. This review aims to elucidate the relationship between interchain forces and/or entanglement with the melt strength and ductility of PLA‐based materials. An essential and systematic understanding of the tailoring melt strength and rheological properties of PLA by interchain forces and/or entanglement was apt to improve and perfect the processing technology of the extrusion blow, and consequently improve the tensile strength and toughness of PLA films. [ABSTRACT FROM AUTHOR]

The electrospun polylactide (PLA) anti‐adhesion fiber‐type film coated with carboxymethylcellulose (CMC) was manufactured and evaluated for its usability through animal experiments. The PLA anti‐adhesion film developed in this study is an adhesion preventive film of a double composite structure with both hydrophobicity and hydrophilicity. This film has the anti‐adhesion effect due to hydrophobic PLA that do not melt easily in the body and at the same time is easily attached to the surgical site by hydrophilic CMC that reacts easily to body fluids and changes quickly to mucus. In this study, the diameter and the pore diameter of the PLA fiber and thickness of PLA film made by electrospinning was 0.2–0.4, 1–10, and 30–50 μm, respectively. Through observation of surface structure (×5000 magnification), the most suitable concentration of CMC to maintain pores on the PLA film as much as possible is 0.5% wt/vol. The CMC content in the PLA film coated with 0.5% wt/vol of CMC was measured to be 5.41% wt/wt and its tensile strength was about 2.92 times higher than that of the noncoated PLA film with CMC. The porosity of CMC‐coated PLA film (5.41% wt/wt) was found to be 76.4%. In the animal experiment, 20 white mice (10 as a control group and 10 as an experimental group) were used to determine the degree of adhesion prevention. As a result of observing adhesion and anti‐adhesion between the cecum and the peritoneum by performing U‐shaped laparotomy on white mice at the third week after surgery, the incidence of adhesion in the control group was 90%, whereas the experimental group was 20%. [ABSTRACT FROM AUTHOR]

This study demonstrates the potential of different cinnamate esters, namely methyl trans‐cinnamate (MC), isobutyl cinnamate (IBC), allyl cinnamate (AC), and ethyl cinnamate (EC), as environmentally friendly plasticizers for polylactide (PLA). Plasticized PLA formulations with a constant nominal wt% of 20 of each plasticizer are compounded in a twin‐screw co‐rotating extruder and subsequently processed by injection molding. The results show exceptional plasticization efficiency of AC with an increase in elongation at break from 3.9% (neat PLA), up to 339.4% and a remarkable increase in impact strength, thus showing great potential to overcome the main drawback related to PLA intrinsic brittleness. The incorporation of cinnamates in a PLA matrix leads to a decrease in Tg from 61.7 °C down to 36.1 °C for the plasticized PLA formulation containing 20 wt% AC. Thermogravimetry analysis reveals that a slight plasticizer loss occurs during processing, as it happens with other monomeric plasticizers, but this phenomenon does not limit their plasticization efficiency. Therefore, the results obtained in this study confirm the suitability of a new family of organic compounds derived from the esterification of cinnamic acid as green plasticizers for PLA with improved toughness, with comparable, or even superior, ductile properties of typical plasticizers for PLA. [ABSTRACT FROM AUTHOR]

Polylactide (PLA) is a fully bio‐derived polyester with great biodegradability, biocompatibility, and mechanical properties. Synthesis of stereoregular PLA by highly stereoselective organocatalyzed ring opening polymerization (ROP) of racemic lactide (rac‐LA) at room temperature is challenging despite some important developments in the past few years. In this contribution, two bulky phenyl diphosphazene bases, p‐PDPB and m‐PDPB, were conveniently synthesized by the Staudinger reaction. In combination with different hydrogen‐bond donors such as ureas and squaramides, they could mediate the stereocontrolled ROP of rac‐LA in THF at room temperature. Semicrystalline PLAs with narrow dispersity and high tacticity (Pm up to 0.84) were successfully synthesized in a well‐controlled manner using phenyl diphosphazene based/urea binary catalytic system. Structural analysis verified the linear structure and high end‐group fidelity of the resulting polymers. Moreover, the minimal transesterification of the polymer backbone proved by the MALDI‐TOF MS analysis indicated the good controllability of the phenyl diphosphazene based binary catalytic system. [ABSTRACT FROM AUTHOR]

A new aliphatic hybrid guanidine N,O‐donor ligand (TMGeech) and its zinc chloride complex ([ZnCl2(TMGeech)]) are presented. This complex displays high catalytic activity for the ring‐opening polymerization (ROP) of lactide in toluene, exceeding the toxic industry standard tin octanoate by a factor of 10. The high catalytic activity of [ZnCl2(TMGeech)] is further demonstrated under industrially preferred melt conditions, reaching high lactide conversions within seconds. To bridge the gap towards a sustainable circular (bio)economy, the catalytic activity of [ZnCl2(TMGeech)] for the chemical recycling of polylactide (PLA) by alcoholysis in THF is investigated. Fast production of different value‐added lactates at mild temperatures is demonstrated. Selective PLA degradation from mixtures with polyethylene terephthalate (PET) and a polymer blend, catalyst recycling, and a detailed kinetic analysis are presented. For the first time, chemical recycling of post‐consumer PET producing different value‐added materials is demonstrated using a guanidine‐based zinc catalyst. Therefore, [ZnCl2(TMGeech)] is a promising, highly active multitool, not only to implement a circular (bio)plastics economy, but also to tackle today's ongoing plastics pollution. [ABSTRACT FROM AUTHOR]

Blending low content of poly[(R)‐3‐hydroxybutyrate‐co‐4‐hydroxybutyrate] (P34HB ≤8 wt %) with poly(L‐lactide) (PLLA) has proven effective in enhancing heat resistance of PLLA fibers. Unfortunately, the enhancement is relatively limited with boiling water shrinkage of PLLA/P34HB blend fibers reduced to 9.9% at most. In this study, a series of PLLA/poly[(R)‐3‐hydroxybutyrate] (PHB) blend fibers with low PHB content (≤8 wt %) was prepared with sound spinnability. Surprisingly, the PLLA/PHB blend fibers showed much lower boiling water shrinkage than the PLLA/P34HB blend fibers with the same blend ratio. In particular, the boiling water shrinkage was dropped from ca. 80% for neat PLLA fibers to 9.9% for the PLA/P34HB blend fibers and further to 3.8% for the PLA/PHB blend fibers with 8 wt % P34HB or PHB added. Such an exceptionally improved heat resistance of the PLLA/PHB blend fibers could be closely related to an increase in crystallinity (Xc,PLLA) of the PLLA phase. Specifically, the mobility of the PLLA segments was promoted in the presence of PHB, along with notably improved orientation of the PLLA phase in the PLLA/PHB blend fibers. More importantly, investigation on crystallization behaviors revealed that the PHB phase served as an effective nucleating agent to accelerate the overall crystallization of PLLA. By contrast, the P34HB phase only acted as spherulite growth‐accelerating and/or nucleation‐assisting agents. These findings help provide a facile and effective strategy to improve heat resistance of PLLA fibers more significantly. [ABSTRACT FROM AUTHOR]

Polymer melt strength (MS) is strongly correlated with its molecular structure, while their relationship is not very clear yet. In this work, designable long‐chain branched polylactide (LCB‐PLA) is prepared in situ by using a tailor‐made (methyl methacrylate)‐co‐(glycidyl methacrylate) copolymer (MG) with accurate number of reactive sites. A new concept of branching density (φ) in the LCB‐PLA system is defined to quantitively study their relationship. Importantly, a critical point of φc = 5.5 mol/104 mol C is revealed for the first time, below which the zero‐shear viscosity (η0) corresponding to MS increases slowly with a slope of Δη0/Δφ = 1400, while it increases sharply above this critical point due to entanglement of neighboring LCB‐PLA chains. Consequently, the MS of PLA increased by >100 times by optimizing the LCB structures while maintaining processibility. Therefore, this work provides a deeper understanding and feasible route in quantitative design of polymers with high(er) melt strength for some specialty applications. [ABSTRACT FROM AUTHOR]

To make full use of the renewability of polylactide (PLA) and natural Eucommia ulmoides gum (EUG), novel fully sustainable thermal plastic vulcanizates (TPVs) with high toughness were developed via dynamic vulcanization technique based on modified EUG (referred to as EUG‐GMA). The latter greatly improved the toughness of PLA and the mechanism was discussed with respect to micro structure analysis. Aiming at providing theoretical guidance for PLA/EUG‐GMA TPVs in scratch related applications, the scratch behavior of TPVs with different EUG‐GMA content was studied in single‐pass and multiple‐pass scratching mode, after which the tribological mechanisms were discussed based on worn surface morphology and contact area analysis. It is revealed that the promoted interfacial adhesion due to in‐situ compatibilization and the co‐continuous phase structure of PLA/EUG‐GMA TPVs played crucial roles in enhancing the TPVs' toughness. In addition to tribo‐conditions, the above mentioned interfacial performance was also responsible for the variation of scratch behavior of different TPVs. It is expected that the present study would open up a new route of manufacturing sustainable composites combined with scratch resistance and toughness. [ABSTRACT FROM AUTHOR]

A previously reported non‐toxic guanidine‐iron catalyst active in the ring opening polymerization (ROP) of polylactide (PLA) under industrially relevant conditions was evaluated for its activity in the alcoholysis and aminolysis of PLA under mild conditions. Kinetic and thermodynamic parameters were determined for the methanolysis of PLA with [FeCl2(TMG5NMe2asme)] (C1) using 1H NMR spectroscopy. A comparison with the Zn analog of C1 showed that the metal center has a large impact on the activity for the alcoholysis. Further, the influence of different nucleophiles was tested broadening the scope of products from PLA waste. C1 is the first discrete metal catalyst reported to be active in the selective aminolysis of PLA. Catalyst recycling, scale‐up experiments and solvent‐free alcoholysis were conducted successfully strengthening the industrial relevance and highlighting aspects of green chemistry. Moreover, the selective depolymerization of PLA in polymer blends was successful. C1 is a promising catalyst for a circular (bio)plastics economy. [ABSTRACT FROM AUTHOR]

Bioplastics are one of the answers to environmental pollution and linear material flows. The most promising bioplastic polylactide (PLA) is already replacing conventional plastics in a number of applications. The properties of PLA, however, do not fit for all potential application areas, but they can be altered by the introduction of comonomers. The copolymerization of lactide (LA) with other lactones like ϵ‐caprolactone (CL) has been established for several years. Nevertheless, controlling copolymerizations remains a challenge due to the high complexity of the system. Copolymerization of LA with other monomer classes is much less investigated, but has the chance to overcome the limitations in material properties that occur when only lactones are used. The crucial factor for all copolymerizations is the catalyst. It dominates the reaction kinetics and determines the resulting microstructure. In this review, copolymerization catalysts for LA are presented divided into catalysts for the synthesis of lactone block copolymers, lactone random copolymers, and multimechanistically synthesized copolymers. The selected catalysts are highlighted either owing to their industrially applicable polymerization conditions or their non‐standard mechanism. [ABSTRACT FROM AUTHOR]

This work reports on the use of dibutyl itaconate (DBI) as an environmentally friendly plasticizer for polylactide (PLA) with different proportions of DBI in the 2.5–20 wt% (weight content) range. A co‐rotating twin‐screw extrusion process followed by injection molding is employed for the manufacturing of the samples. The results show that the plasticized PLA formulation with 10 wt% DBI offers the most balanced overall properties, with a noticeable increase in the elongation at break from 4.6% (neat PLA) up to 322%, with a tensile modulus of 1572 MPa, and a tensile strength of 23.8 MPa. In the case of 15 and 20 wt% DBI formulations, PLA reaches the saturation point with no more increase in the elongation at break and a clear decrease in the tensile modulus. DBI also decreases the glass transition temperature (Tg) from 61.3 °C (neat PLA) down to 23.4 °C for plasticized PLA formulation containing 20 wt% DBI, thus showing the high plasticization efficiency of DBI. [ABSTRACT FROM AUTHOR]

Stereoblock polylactide (Sb‐PLA) was prepared via a consecutive method by ring‐opening polymerization and its stereocomplex crystallization behavior was investigated by differential scanning calorimetry (DSC), polarized optical microscopy (POM). The molecular weight, sequence structure of anisotropic segments of Sb‐PLA and crystals structure were characterized by using GPC, 1H NMR, 13C NMR and XRD. The Sb‐PLA with bonding a higher stereoregularity chains prepared by the synthesis route exhibited a higher melting point and uniquely stereocomplex crystallization behavior compared with the Sb‐PLA prepared by commonly reported method. The isothermal crystallization results indicated that the crystallization temperature of Sb‐PLA's increased about 20°C higher than reported Sc‐PLA materials. Moreover, crystallization rate constant (K) and crystallization activation energy (ΔE) expressed by the Arrhenius equation demonstrated that Sb‐PLA presents a higher crystallization rate. The data of isothermal crystallization experiments were analyzed based on Lauritzen–Hoffman (LH) theory, crystallization rate constant (G0), nucleation constant (Kg), fold surface free energy (σe), and folding work (q) were estimated to be 1.5 × 1027 μm/min, 1.2 × 106 K2, 113.0 erg/cm2 and 8.20 × 10−21 J, respectively. These results indicated that Sb‐PLA chains with a higher stereoregularity suggested to be the main factor accounting for the formation unique stereocomplex crystals. [ABSTRACT FROM AUTHOR]

Stiffness–toughness balance is an important issue in rubber toughened polymer blends. In this work, a facile and effective route to simultaneously toughen and reinforce polylactide (PLA) by regulating the distribution of core–shell rubber (CSR) nanoparticles with carbon black (CB) is reported. The PLA/CSR/CB nanocomposites are prepared via direct melt‐blending PLA, CSR, and CB nanoparticles with different self‐aggregate capabilities. The FTIR and DFT calculation results reveal that the interactions between CB and CSR are stronger than those between CB and PLA. Thus, CB nanoparticles with high self‐aggregate capability (HCB) can drive CSR nanoparticles to join into the HCB network structures and form CSR‐HCB network structures in the PLA/CSR/HCB nanocomposites. However, for the CB nanoparticles with low self‐aggregate capability (LCB), uniform dispersion of both CSR nanoparticles and small‐sized CB clusters in the PLA/CSR/LCB nanocomposites is observed. Compared to the network structures, the uniform dispersion structure can endow PLA/CSR/CB nanocomposites with much better stiffness–toughness balance performances. Additionally, the distribution of CSR nanoparticles on the rheological properties of PLA/CSR/CB nanocomposites are studied. This work reveals significant correlations between distribution of CSR nanoparticles and properties of PLA nanocomposites, which is helpful to prepare high‐performance PLA materials. [ABSTRACT FROM AUTHOR]

This work aims at preparing bioderived polymer films by blending poly(lactic) acid (PLA) and poly(dodecylene 2,5‐furandicarboxylate) (PDoF) and containing reduced graphene oxide (rGO) as a multifunctional filler in variable weight fraction (from 0.25 to 2 phr). Although the PLA/PDoF blend results as immiscible, the addition of rGO leads to smaller (from 2.6 to 1.6 µm) and more irregularly shaped PDoF domains and to a better PLA/PDoF interfacial adhesion, which suggests that rGO may act as a blend compatibilizer. Dynamic mechanical thermal analysis (DMTA) shows that rGO shifts the glass transition of PDoF (≈5°C) to higher temperatures. The addition of 10 wt% PDoF in PLA increases the strain at break (+145%), and the addition of 0.25 phr of rGO to this blend increases its tensile strength (+13%), without significantly modifying the strain at break. Finally, rGO strongly decreases the diffusivity and permeability to O2, N2, and CO2 due to an increased diffusion path for gas molecules. These results highlight the positive and sometimes synergistic role of PDoF and rGO in tuning the thermomechanical and gas permeation properties of PLA. [ABSTRACT FROM AUTHOR]

In this study, the synthesis of two new guanidine hydroquinoline ligands served as basis for six new zinc guanidine complexes. Two of these complexes showed very high activity in the lactide polymerization under industrial conditions. The lactide polymerization was demonstrated in solution and melt conditions observing high activity and molar masses up to 90 000 g mol−1. Density functional theory studies elucidated the high activity of the complexes associated with the influence of the ligand backbone and the use of triflate counterions. On the way towards a circular economy, polymerization and depolymerization go hand in hand. So far, guanidine complexes have only shown their good activity in the ring opening polymerization of esters, and guanidine complexes with pure N donors have not been tested in recycling processes. Herein, the excellent ability of zinc guanidine complexes to catalyze both polymerization and depolymerization was demonstrated. The two most promising zinc complexes efficiently mediated the methanolysis of polylactide into methyl lactate under mild reaction conditions. [ABSTRACT FROM AUTHOR]

The use of lignocellulosic fibers into polymer matrices gained attention of the researchers and brought substantial research. The main objective of this research work is to determine the thermal characteristics and hygrothermal aging of untreated and surface modified Agave Cantala plant fiber‐reinforced polylactide composites. Cellulosic fibers were extracted from the fleshy leaves of the plant by water and mechanical retting processes. The extracted fibers were treated with trimethoxy methyl silane and fabrication of the composites was done using matched die molding method. These composites are characterized by thermo‐gravimetry analysis, Fourier transform infrared spectroscopy, X‐ray diffraction study, hygrothermal aging, energy dispersive X‐ray spectroscopy and field emission scanning electron microscopy analysis. The results showed the trimethoxy methyl silane treated A. Cantala treated fiber reinforced composites exhibiting better thermal, hygrothermal, and morphological behavior. [ABSTRACT FROM AUTHOR]

The degradation of polylactide (PLA) under UV exposure is investigated in terms of cooperativity and kinetic fragility at the glass transition. In the first part, possibly coexisting degradation mechanisms are evoked from the interpretation of the infrared spectroscopy analyses. Furthermore, the reduction of PLA chain length, owing to photolytic scissions predominant over local crosslinks, is assessed from chromatography, and confirmed by the shift of the glass transition temperature toward lower temperature. Modulated temperature thermogravimetric analysis (MT‐TGA) also shows that the activation energy needed to initiate thermal degradation falls after UV exposure. In the second part, the impact of UV‐induced degradation on the cooperative rearranging region (CRR) size and the kinetic fragility, respectively, calculated thanks to calorimetric and dielectric measurements, is discussed. Despite the assumed concomitance of several degradation mechanisms, it is observed that the glass transition, the kinetic fragility, and the CRR size decrease together with the exposure time. Moreover, it is found that the data align well on another trend depicting the change in the relaxation properties caused by plasticization of PLA. Thus, the variations of segmental relaxation properties caused by UV may be related to the increase of free volume linked to the damaging of the PLA structure. [ABSTRACT FROM AUTHOR]

The ABCBA pentablock copolymers (p‐d‐l‐PPS) comprising poly(d‐lactide) (PDLA: A), poly(l‐lactide) (PLLA: B) and poly(propylene succinate) (PPS: C) were successfully synthesized by two‐step ring‐opening polymerization (ROP) of d‐ and l‐lactide using a dihydroxy‐terminated PPS as a macro‐initiator. The pentablock copolymers revealed the high stereocomplex (sc) crystallinity, thermal stability and elastomeric property in their solution‐cast films. It was found that the Tg was found to be proportional to the PPS content, whereas the Tm was proportional to their average block length. The thermal resistivity of the copolymer films was found to be as high as 202°C owing to their sc formation. The copolymers also showed improved stereocomplexibility compared to the enantiomeric mixtures of triblock copolymers (PLLA‐PPS‐PLLA and PDLA‐PPS‐PDLA) having similar PLLA and PDLA chain lengths. These pentablock copolymers can afford thermoplastic elastomers or flexible plastic materials having a 100% bio‐based content, showing high heat‐resistive property. [ABSTRACT FROM AUTHOR]

Here for the first time, this work indicated that the sericin‐g‐polylactide (SS‐g‐PLA) copolymer can be potentially used as an organic nucleating agent to improve the crystallinity and biodegradability of polylactide (PLA). The properties of blended films containing SS‐g‐PLA mixed with virgin PLA polymer were highly evaluated. The water vapor permeability (WVP), thermal behavior, dynamic mechanical properties, crystal structure, and biodegradability of the PLA/SS‐g‐PLA‐blended films were characterized and compared with a commercial PLA film. The results clearly indicated that the incorporation of SS‐g‐PLA copolymer in the PLA matrix had a significant effect on the properties of PLA/SS‐g‐PLA‐blended films. The WVP values of PLA/SS‐g‐PLA‐blended films were lower than that of commercial PLA film by about 2–3 g·mm/m2·day·atm, and their thermal behaviors (e.g. Tg, Tcc, and Tm) were also decreased. Adding SS‐g‐PLA can increase the crystallinity of PLA. The degree of crystallinity (%χc) of the series of PLA/SS‐g‐PLA‐blended films was increased to about 2–4 times that of the commercial PLA film (3%). Interestingly, biodegradation results revealed that the percent of biodegradability of PLA/SS‐g‐PLA‐blended film was 80% in 43 days under a compost environmental temperature of 58 ± 2°C. This evidence indicated that the SS‐g‐PLA copolymer can improve the biodegradability of PLA. [ABSTRACT FROM AUTHOR]

Tears in the rotator cuff are challenging to repair because of the complex, hypocellular, hypovascular, and movement‐active nature of the tendon and its enthesis. Insulin‐like Growth Factor‐1 (IGF‐1) is a promising therapeutic for this repair. However, its unstable nature, short half‐life, and ability to disrupt homeostasis has limited its clinical translation. Pegylation has been shown to improve the stability and sustain IGF‐1 levels in the systemic circulation without disrupting homeostasis. To provide localized delivery of IGF‐1 in the repaired tendons, we encapsulated pegylated IGF‐1 mimic and its controls (unpegylated IGF‐1 mimic and recombinant human IGF‐1) in polycaprolactone‐based matrices and evaluated them in a pre‐clinical rodent model of rotator cuff repair. Pegylated‐IGF‐1 mimic delivery reestablished the characteristic tendon‐to‐bone enthesis structure and improved tendon tensile properties within 8 weeks of repair compared to controls, signifying the importance of pegylation in this complex tissue regeneration. These results demonstrate a simple and scalable biologic delivery technology alternative to tissue‐derived grafts for soft tissue repair. [ABSTRACT FROM AUTHOR]

Core–shell structured particles have been used to toughen brittle polylactide (PLA) extensively. In this research, reactive core–shell (RCS) particles with polybutadiene (PB) as core and the terpolymer styrene–acrylonitrile‐glycidyl methacrylate as shell were prepared to improve the toughening ability of RCS for PLA. The tert‐dodecyl mercaptan (TDDM) content was varied during polymerization and higher TDDM concentrations induced lower grafting and cross‐linking of the PB phase, which significantly influenced the dispersed phase morphology and toughness of RCS toughened PLA blends. With the increase of TDDM content, the phase morphology of RCS changed from uniform dispersion, net‐like structure to an agglomeration pattern. The impact strength of PLA blends increased with TDDM content and reached 922 J/m for the PLA/RCS‐T5 (TDDM: 1.18 wt%), which was 30 times higher than pristine PLA and ~3 times than PLA/RCS‐T0 blend. Higher TDDM contents decreased toughening efficiency. Appropriate TDDM contents decreased the glass transition temperature (Tg) and cross‐linking degree of RCS particles which enhanced the cavitation ability of the PB core phase and promoted the shear yielding of PLA matrix. The modification effect of TDDM solves the problem of insufficient toughening ability of core–shell particles. Under the same toughener content, the modified RCS particles make the PLA blend achieve super toughness. [ABSTRACT FROM AUTHOR]

Bio‐based plasticizers are a significant replacement for petrochemical‐based plasticizers because they are from renewable resources. The plasticizing effect of lanolin‐based oil at a different concentration and as an additive on polylactide's thermal and chemical stability (PLA) was investigated. The thermal stability was assessed using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The plasticized PLA samples were also analyzed with a dynamic mechanical analyzer (DMA), X‐ray powder diffraction (powder XRD), and infrared (IR) spectroscopy. The plasticizer modified the thermal stability of the PLA polymer by increasing the cold crystallization temperature (Tcc), as shown by DSC. At the same time, the DMA data indicated a reduction in the dynamic storage modulus and glass transition temperature (Tg) with increased amounts of plasticizer content. The powder X‐ray diffraction patterns showed that the PLA has no polymorphic crystalline transition with the oil plasticizer. The analysis from the results shows the oil additive's potential as a bio‐based plasticizer for PLA However, further performance improvements are required for large‐scale production. From the results obtained, there are enhancements in the thermal and physical properties of the modified PLA, and it is suitable for composite production. [ABSTRACT FROM AUTHOR]

The highly miniaturized and integrated electronic devices have demanded contactless current sensors with scale miniaturization, structure flexibility, self‐powering and heat resistance. Herein, a novel magnetoelectric current sensor (MCS) based on polylactide/VB2 composites and FeCoV is prepared using in‐situ coating and poling‐free methods. The use of polylactide/VB2 composite makes the MCS self‐powered and heat resistant, and the use of FeCoV makes the MCS highly flexible. The in‐situ coating and poling‐free methods endow the polylactide/VB2 composite and FeCoV good interfacial coupling. As a result, the MCS possesses good linearity over 0.999 and high sensitivity of 0.64 mV/A to the external current, even at a high temperature of 120 °C. Besides, the MCS presents high durability after 200 000 cycles. The MCS with mini size, self‐powering, heat resistance, high flexibility and durability has great potential in safety monitoring of electronic devices fields. [ABSTRACT FROM AUTHOR]

Ring‐opening polymerizations (ROP) of l‐lactide (LA) are conducted in bulk at 130, 160, or 180 °C and are initiated with two different alcohols at 160 °C. The lactide/initiator ratio (LA/In) is varied from 50/1 (20/1 at 180 °C) to 900/1 and the lactide/catalyst ratio (LA/Cat) between 2000/1 and 8000/1. At all temperatures a nearly perfect control of number average molecular weight (Mn) via the LA/In ratio is feasible up to LA/In = 200/1, but at higher ratios the Mn value lags behind the theoretical values and the discrepancy increases with higher LA/Cat ratios. Variation of the LA/Cat ratio influences the formation of cycles but does not significantly influence Mn, when the LA/In ratio is kept constant. The formation of cycles is favored by lower In/Cat ratios and is the main reason for the unsatisfactory control of Mn at high LA/In ratios. The results also suggest that the cycles are mainly or exclusively formed by end‐to‐end cyclization and not, as believed previously, by back‐biting. [ABSTRACT FROM AUTHOR]

Hydrolytic degradation of polylactides (PLAs) bearing cinnamic acid derivatives was conducted and their thermal degradation temperature at 10% weight loss (T10) and melting point temperature (Tm) were measured, to confirm that a PLA stereocomplex could be modified for use in a wide range of application. The improved T10 values of PLA films by chain end modification were maintained after the alkaline degradation. The increase in Tm by stereocomplex formation was also maintained after degradation with a slight change in the melting point of the attached homopolymer. The present results indicate the suitability of chain end modification for the additional functionality of PLA stereocomplex films. [ABSTRACT FROM AUTHOR]

We developed a new approach to obtain polylactide hybrid block copolymers with vinyl monomers (styrene, methyl methacrylate, methyl acrylate) through the realization of a reaction sequence using triethylborane and various p‐quinones. The method offered includes two stages. In the first stage, a chain‐transfer agent was obtained by borylation of the terminal hydroxyl groups of polylactide. The second stage was vinyl monomer radical polymerization in the presence of p‐quinone accompanied by SH2‐substitution at the boron atom.1,4‐Naphthoquinone, 2,3‐dimethyl‐1,4‐benzoquinone, duroquinone and 2,5‐di‐tert‐butyl‐1,4‐benzoquinone were used as synthetic polymer chain growth mediators. It is shown that 1,4‐naphthoquinone and 2,3‐dimethyl‐1,4‐benzoquinone, similar in their characteristics, are effective agents providing the realization of reversible‐deactivation radical polymerization. Realization of reversible‐deactivation radical polymerization was proved with the analysis of the kinetics of block copolymerization, molecular weight characteristics and compositional homogeneity of block copolymers as well as its further capability to elongate the polymer chain. Synthesized block copolymers have a high thermal stability compared to the initial borylated polylactide. © 2021 Society of Industrial Chemistry. [ABSTRACT FROM AUTHOR]

In contrast to other cyclic tin bisphenoxides, polymerizations of glycolide and l‐lactide with the spirocyclic tin(IV) bis‐1,1′‐bisnapthoxide yield linear chains having a 1,1′‐bisnapthol end group and no cycles. In the case of l‐lactide, LA/Cat ratio and temperature are varied and at 160 °C or below, all polylactides mainly consist of even‐numbered chains. A total predominance of even‐numbered chains is also found for homopolymerization of glycolide, or the copolymerization of glycolide and l‐lactide, when conducted <120 °C. Linear chains having a bisnaphthol end group are again the main reaction products of ring‐expansion polymerizations (REP) of ε‐caprolactone, but above 150 °C cycles are also formed. [ABSTRACT FROM AUTHOR]

A simple zinc catalyst showing high activity for both the synthesis of polylactide, a biodegradable polymer produced from renewable feedstock, and its degradation was described. In the ring‐opening polymerization of lactides, the zinc catalyst showed one of the highest activities reported in the literature for reactions carried out in solution at room temperature. This excellent performance was preserved even when the process was performed under industrial conditions: at high temperature, in the absence of solvent, and by using a low catalyst loading with unpurified monomers. The same complex revealed high efficiency also in depolymerization of polylactide by alcoholysis, a process that occurred efficiently at room temperature and in the absence of solvent, conditions that reduce costs and guarantee low environmental impact. [ABSTRACT FROM AUTHOR]

This work reports on the development of polylactide (PLA) and polycarbonate (PC) blends with different compatibilizers with enhanced toughness. Since both polymers are immiscible, two types of compatibilizers are tested: petrochemical‐based copolymers Xibond 160 and Xibond 920 with maleic anhydride and epoxy groups, respectively, and natural‐based compatibilizers with the same functionalities, namely maleinized linseed oil (MLO) and, epoxidized linseed oil (ELO). Mechanical, thermal, and morphological characterization shows better properties for the PLA/PC (80/20 wt%) blends with chemically modified natural oils (ELO and MLO). The addition of 5 phr (parts per hundred resin) of MLO gives the maximum values for impact strength and elongation at break. Moreover, the glass transition temperature (Tg) slightly decreases with the addition of natural compatibilizers, thus showing some plasticization effect. Petroleum‐derived compatibilizers give interesting results regarding tensile strength and stiffness without plasticization. PLA/PC blends show higher thermal stability than neat PLA, regardless of the compatibilizer used, since PC is much more thermally stable than PLA. The obtained results indicate that both petroleum‐based and natural‐derived compatibilizers positively contribute to enhance the properties of the binary PLA/PC blends. Nevertheless, the results with MLO suggest this is an interesting biobased solution to provide increased toughness to PLA/PC blends. [ABSTRACT FROM AUTHOR]

In 2002, Robert Langer proposed that new polyester for tissue engineering should have good mechanical properties followed by: covalent bonding (as crosslinking) and hydrogen‐bonding interactions; and should be elastic like rubber materials due to three‐dimensional network structure. Considering these hypotheses, a polyester made of glycerol and citric acid was designed in this work. Poly(glycerol citrate) should be attractive for tissue engineering because both glycerol and citric acid, taking part in natural human metabolic pathways; and due to the reactant's functionality, 3D networks should be produced easily. Moreover, the reagents are cheap, available, and often used in the food and pharmaceutical industries. In this work, poly(glycerol citrate) was synthesized and then used with PLA for creating porous nonwovens by electrospinning. Produced materials were tested for possible application in the field of tissue engineering. The obtained materials have properties similar to collagen fibers, but still, require refinement for medical applications. [ABSTRACT FROM AUTHOR]

Main observation and conclusion: A series of novel polyethylene glycol‐dicationic imidazolium‐based ionic liquids (mPEG‐ILs) were synthesized by facile quaternization reaction from various elaborately designed di‐imidazoles and PEG, which were then studied as green plasticizers for sustainable polylactide (PLA) material. The influences of the chain structure, content, and molecular weight of the mPEG‐ILs on the plasticizing effect were systematically investigated by characterization of a series of PLA/mPEG‐ILs blending systems. FTIR results show there is combination of ion‐dipole interaction and hydrogen bonds interaction between PLA and mPEG‐ILs, which is beneficial for the compatibility. Thermal behaviors indicate that mPEG‐ILs have a significant plasticizing effect on PLA. Particularly, mPEG400‐amide‐IM can remarkably improve the mobility of PLA chain, leading to decreased glass transition temperature (Tg) and cold crystallization temperature (Tcc) of PLA. Tensile test results show that the ductility of plasticized PLA is greatly enhanced, and its elongation at break reaches 249.4%, which is 22 times that of neat PLA. [ABSTRACT FROM AUTHOR]

Cells‐containing scaffolds made of biomaterial are modern hybrid constructs which allow regeneration or reconstruction of damaged connective tissue, e.g. cartilage or bone. The basic aim of the study was to recognize the impact of the scaffold production parameters (i.e. type of applied pore precursor, its concentration) on morphology and mechanical properties of polylactide (PLLA) membrane‐based constructs, as well as their biocompatibility exhibited as cellular response. Design of experiments (DoE) strategy has been applied to quantitatively recognize the effects of synthesis parameters on PLLA‐membrane properties. Two independent correlations have been introduced to provide the influence of the synthesis parameters on the pore size, as well as the Young's modulus identifying the surface properties of scaffolds. PLLA membrane‐based scaffolds characterized by average pore diameter exceeded 100 microns and average Young's modulus exceeded 10 MPa have been obtained. The evaluation of scaffolds biocompatibility has been performed due to comprehensive analysis of proliferation effects and metabolic activity of mouse L929 fibroblasts maintained on the surface of developed PLLA‐membranes. The Application of PVP as the pore precursor positively impacted on the surface properties of the constructs. The lack of cytotoxicity of the developed PLLA membranes has been detected. [ABSTRACT FROM AUTHOR]

Main observation and conclusion: Ring‐opening polymerization (ROP) of cyclic esters in the presence of stannous octoate (Sn(Oct)2) is the main way to obtain biodegradable aliphatic polyesters, an important family of biodegradable polymers which have been widely used and still rapidly developed in the fields of biomedical polymers and environment‐friendly materials. The underlying mechanism is thought via a coordination‐insertion way, but the pathway is still open owing to the absence of direct experimental evidence. Herein, we inquire this issue through density functional theory (DFT) calculations. According to our DFT calculations and the following Curtin‐Hammett evaluation, the carbonyl oxygen has a significant advantage over the ester oxygen, and thus the ring is opened mainly through pathway A instead of pathway B. The stannous octoate is identified as a catalyst rather than an initiator. We eventually summarize the main stages during the whole polymerization of lactide. [ABSTRACT FROM AUTHOR]