PEGylated poly(ester amide) elastomer scaffolds for soft tissue engineering

Biodegradable synthetic elastomers with tunable mechanical and physicochemical properties remain attractive materials for soft tissue engineering. We have recently synthesized novel poly(1,3‐diamino‐2‐hydroxypropane‐co‐glycerol sebacate)‐co‐poly(ethylene glycol) (APS‐co‐PEG) biodegradable elastomers. This class of PEGylated elastomers has widely tunable mechanical and degradation properties compared wtih currently available biodegradable elastomers. To further investigate the biological application of this class of elastomers, we fabricated hybrid APS‐co‐PEG/polycaprolactone (PCL) porous scaffolds by electrospinning. The fiber morphology, chemical composition, mechanical properties, degradability, and cytocompatibility of hybrid APS‐co‐PEG/PCL electrospun scaffolds were characterized. These scaffolds exhibited a wide range of mechanical properties and similar cytocompatibility to PCL scaffolds. Importantly, PEGylation inhibited platelet adhesion on all APS‐co‐PEG/PCL electrospun scaffolds when compared with PCL and APS/PCL scaffolds, suggesting a potential role in mitigating thrombogenicity in vivo. Additionally, APS‐25PEG/PCL scaffolds were found to be mechanically analogous to human heart valve leaflet and supported attachment of human aortic valve cells. These results reveal that hybrid APS‐co‐PEG/PCL scaffolds may serve as promising constructs for soft tissue engineering, especially heart valve tissue engineering. Copyright © 2017 John Wiley & Sons, Ltd.     

Synthesis and characterization of poly(p-dioxanone)-based degradable copolymers with enhanced thermal and hydrolytic stabilities

Herein, we presented a novel biodegradable copolymer via the chain extending reaction of poly(p-dioxanone)-co-poly(2-(2-hydroxyethoxy) benzoate) (PPDO-co-PDHB) prepolymer with hexamethylene diisocyanate (HDI) as a chain extender. The structures and molecular weight of PPDO-co-PDHB prepolymer and PPDO-co-PDHB-PU chain-extended copolymer are characterized via hydrogen nuclear magnetic resonance spectroscopy (¹H NMR) and viscosity test. The relationship between the molecular structures and properties of the chain-extended copolymers is established. The PPDO-co-PDHB-PU copolymers possess a better thermal stability comparing with the PPDO homopolymer. The study of mechanical properties shows that the elongation-at-break of PPDO-co-PDHB-PU is much higher than that of PPDO. The investigation of hydrolytic degradation behaviors indicates the degradation rate of PPDO can be controlled by adjusting the PDHB compositions, and proves that chain-extended copolymers exhibit an excellent hydrolytic stability being better than that of PPDO.     

3D printed PCL scaffold reinforced with continuous biodegradable fiber yarn: A study on mechanical and cell viability properties

In this study, poly (ε‐caprolactone) (PCL) scaffolds were printed and reinforced, simultaneously, with biodegradable poly glycolic acid (PGA) suture yarn, as a continuous reinforcing fiber, in the Fused Deposition Modeling (FDM) 3D printing process. Albeit PCL is a suitable material for biomedical applications, its low mechanical properties, and low degradation rate have limited its usage. A biocompatible suture yarn was used as the reinforcing material to enhance the mechanical properties and biodegradation characteristics, via an innovative method of continuous fiber embedding in the FDM process. The reinforced PCL samples were 3D printed with the setting porosity value of 60% and 0°/60°/120° lay-down pattern. The mechanical and biological properties of the scaffolds were tested to prove the effectiveness of the produced scaffolds for bone substitute purposes. Mechanical properties assessments showed that with a 22 vol.% suture yarn content in the 3D printed PCL scaffolds, the tensile strength, and elastic modulus remarkably increased up to 374% and 775%, respectively. The degradation of the reinforced PCL was 20 times higher than that of the non-reinforced PCL samples, after ten weeks, dominated by the fiber degradation phenomenon. After three days of cell culture, the proliferation assay of the built scaffovd the non-toxicity of the reinforced PCL.     

Degradation of cross-linked aliphatic polyester composed of poly(?-caprolactone-co-d,l-lactide) depending on the thermal properties

In this study, we prepared cross-linked aliphatic polyester derived from branched poly(?-caprolactone (abbreviated as CL)-co-d,l-lactide (abbreviated as LA)) macromonomers with different CL and LA compositions and investigated the effect of thermal properties on their degradation. According to the degradation study, the weight loss became larger with increasing LA composition in poly(CL-co-LA). The introduction of LA units that can degrade easily disturbed the crystallinity of the PCL segments; as result, the hydrolysis became accelerated. Also, we studied the temperature dependency of degradation of a series of cross-linked poly(CL-co-LA) materials with different melting points. We found that the degradation of these materials related closely to the crystallinity, which could be controlled by the composition of CL and LA.     

Preparation,Characterization, and In Vitro Biological Evaluation of PLGA/Nano-Fluorohydroxyapatite (FHA) Microsphere-Sintered Scaffolds for Biomedical Applications

In this research, the novel three-dimensional (3D) porous scaffolds made of poly(lactic-co-glycolic acid) (PLGA)/nano-fluorohydroxyapatite (FHA) composite microspheres was prepared and characterize for potential bone repair applications. We employed a microsphere sintering method to produce 3D PLGA/nano-FHA scaffolds composite microspheres. The mechanical properties, pore size, and porosity of the composite scaffolds were controlled by varying parameters, such as sintering temperature, sintering time, and PLGA/nano-FHA ratio. The experimental results showed that the PLGA/nano-FHA (4:1) scaffold sintered at 90 °C for 2 h demonstrated the highest mechanical properties and an appropriate pore structure for bone tissue engineering applications. Furthermore, MTT assay and alkaline phosphatase activity (ALP activity) results ascertained that a general trend of increasing in cell viability was seen for PLGA/nano-FHA (4:1) scaffold sintered at 90 °C for 2 h by time with compared to control group. Eventually, obtained experimental results demonstrated PLGA/nano-FHA microsphere-sintered scaffold deserve attention utilizing for bone tissue engineering.     

Mechanical, thermal and degradation properties of poly(d,l-lactide)/poly(hydroxybutyrate-co-hydroxyvalerate)/poly(ethylene glycol) blend

The mechanical, thermal and biodegradable properties of poly(d,l-lactide) (PDLLA), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and poly(ethylene glycol) (PEG) blends were studied. The influence of PEG on the tensile and impact strengths of the blends was investigated. The results showed that the toughness and elongation at break of the PDLLA/PHBV (70/30) blends were greatly improved by the addition of PEG, and the notched Izod impact strength increased about 400% and the elongation at break increased from 2.1% to 237.0%. The thermal and degradation properties of the blends were investigated by differential scanning calorimeter (DSC) and thermogravimetric analyzer (TGA), it was found that the thermal stability of PHBV in the presence of PDLLA was improved. The degradation test showed that the addition of PEG could notably accelerate the biodegradation of the blends in the soil at room temperature, and the mass loss is about 20% after 30 days of the storage.     

Preparation and characterization of aliphatic/aromatic copolyesters based on 1,4-cyclohexanedicarboxylic acid

A series of biodegradable aliphatic/aromatic copolyesters, poly(butylene terephthalate)-co-poly(butylene cyclohexanedicarboxylate)-b-poly(ethylene glycol) (PTCG), were prepared by a two-step melt polycondensation method and characterized by means of GPC, FTIR, NMR, DSC, TGA, etc. The effects of aliphatic ester content on the physical, mechanical and thermal properties, as well as in vitro and in vivo degradation behaviors were investigated. The decrease in mechanical strength was observed with an increase in poly(butylene cyclohexanedicarboxylate) (PBC) molar fraction. DSC results showed one melting point and two glass transition temperatures in all samples, and the melting temperature was found to go down gradually as more cyclohexanedicarboxylic acid (CHDA) was added. During the in vitro and in vivo degradation processes, erosion of the surface was dominant as evidenced by scanning electron microscopic observations. The copolyesters containing many CHDA units were featured by the higher water uptake and faster degradation due to much richer amorphous phase within them.     

Curcumin‐loaded biodegradable polyurethane scaffolds modified with gelatin using 3D printing technology for cartilage tissue engineering

We described the curcumin‐loaded biodegradable polyurethane (PU) scaffolds modified with gelatin based on three‐dimensional (3D) printing technology for potential application of cartilage regeneration. The printing solution of poly(ε‐caprolactone) (PCL) triol (polyol) and hexamethylene diisocyanate (HMDI) in 2,2,2‐trifluoroethanol was printed through a nozzle in dimethyl sulfoxide phase with or without gelatin. The weight ratio of HMDI against PCL triol was varied as 3, 5, and 7 in order to evaluate its effect on the mechanical properties and biodegradation rate. A higher ratio of HMDI resulted in higher mechanical properties and a lower biodegradation rate. The use of gelatin increased the mechanical properties, biodegradation rate, and curcumin release due to the surface cross‐linking, nanoporous structure, and surface hydrophilicity of the scaffolds. In vitro study revealed that the released curcumin enhanced the proliferation and differentiation of chondrocyte. The 3D‐printed biodegradable PU scaffold modified with gelatin should thus be considered as a potential candidate for cartilage regeneration.     

High performance of interpenetrating polymer network hydrogels induced by frontal polymerization

We report the rapid synthesis of hydrogels with interpenetrating polymer networks (IPNs) by frontal polymerization (FP). Appropriate amounts of diacetone acrylamide (DAAM), N-methylolacrylamide (NMA), thermoplastic polyurethane (TPU), N,N′-methylenebisacrylamide (MBAA), and ammonium persulfate (APS)/N,N,N′,N′-tetramethylethylenediamine (TMEDA) were mixed together at ambient temperature. FP was initiated by transitorily heating the upper side of the reactants, and poly(DAAM-co-NMA)/TPU IPN hydrogels were obtained within minutes. The preparation parameters were thoroughly investigated. Moreover, we investigated the morphology, swelling capacity, chemical structure and the mechanical properties of poly(DAAM-co-NMA)/TPU IPN hydrogels, along with those of poly(DAAM-co-NMA) hydrogels without IPN structure for comparison. Interestingly, the mechanical strength of poly(DAAM-co-NMA)/TPU IPN hydrogels is notably improved in comparison with that of poly(DAAM-co-NMA) hydrogels. The results indicate that the IPN structure endows hydrogels with high mechanical strength, and FP can be applied as an alternative means for synthesis of IPN hydrogels with additional advantages of speed and efficiency.     

Synthesis, characterization and degradability of the comb-type poly(4-hydroxyl-ε-caprolactone-co-ε-caprolactone)-g-poly(l-lactide)

The novel comb-type biodegradable graft copolymers based on ε-caprolactone and l-lactide were synthesized. Firstly, 2-oxepane-1,5-dione (OPD) was synthesized by the Baeyer-Villiger oxidation of 1,4-cyclohexanedione, and was subsequently copolymerized with ε-caprolactone (CL) to produce poly(2-oxepane-1,5-dione-co-ε-caprolactone) (POCL) catalyzed by stannous(II) 2-ethylhexanoate in toluene. Then, POCL was converted into poly(4-hydroxyl-ε-caprolactone-co-ε-caprolactone) (PHCL) using sodium borohydride as reductant. Finally, poly(4-hydroxyl-ε-caprolactone-co-ε-caprolactone)-g-poly(l-lactide) (PHCL-g-PLLA) were prepared successfully by bulk ring-opening polymerization of l-lactide using PHCL as a macro-initiator. All the copolymers have been characterized by ¹H and ¹³C NMR, DSC, and GPC. Compared with the random copolymer of poly(CL-co-LA), the elongation is highly increased. And the thermal analysis showed that the crystallization rate of the PCL backbone in the graft copolymers was greatly reduced compared to the PCL homopolymer. The hydrolytic degradation of the copolymer was much faster in a phosphate buffer (pH = 7.4) at 37 °C, which is confirmed by the weight loss and change of intrinsic viscosity.     

Modification of hydrophilic poly(vinyl alcohol) film via blending with hydrophobic poly(butyl acrylate-co-methyl methacrylate)

A series of poly(vinyl alcohol)/poly(butyl acrylate-co-methyl methacrylate) [PVA/P(BA-co-MMA)] blend films with different P(BA-co-MMA) content were prepared by the solution casting method. Surface morphologies of the PVA/P(BA-co-MMA) blend films were studied by scanning electron microscopy and atomic force microscopy. Thermal, mechanical, and chemical properties of PVA/P(BA-co-MMA) blend films were investigated by differential scanning calorimeter, thermogravimetric analysis, tensile tests, and surface contact angle tests. It was revealed that the introduction of P(BA-co-MMA) could affect the properties of the PVA films. The results also showed that, when P(BA-co-MMA) mole content is 3 %, the tensile strength and the surface contact angle of the polymer blend film are 20.4 MPa and 43.5°, respectively, suggesting that the polymer blend film holds both a better mechanical property and a better chemical property.     

Poly(l,l-lactide-co-glycolide)/tricalcium phosphate composite scaffold and its various changes during degradation in vitro

A poly(l,l-lactide-co-glycolide) (70/30)/(tricalcium phosphate) (PLGA/TCP) composite scaffold was fabricated by low-temperature deposition (LDM) and its degradation performed in vitro for 22 weeks. Various changes during degradation in vitro, which included changes in acidity of the degradation medium, morphology, weight, composition, molecular weight of the PLGA component and mechanical properties of the scaffold, were investigated. It was found that the acidity of degradation medium of the PLGA(70/30)/TCP composite scaffolds reduced and became much lower than that of TCP-free scaffold. With degradation, the volume and porosity of the PLGA(70/30)/TCP composite scaffold reduced at first then increased slowly, while the surface morphology of the scaffold changed from smooth to rough. The weight loss of the scaffold increased by dissolution of the degraded products and TCP component, but mainly by dissolution of the glycyl-rich degraded products of the PLGA component. The molecular weight of the PLGA component reduced with time, but the molecular weight distribution increased at first and then reduced. The compressive strength and modulus of the scaffold increased at first and then reduced with further degradation. The effect of degradation on modulus was much bigger than that on compressive strength. Based on excellent cell affinity of the PLGA(70/30)/TCP composite scaffold, a potentially useful bone tissue engineering scaffold is proposed.     

Improvement in gas permeability of biaxially stretched PET films blended with high barrier polymers: The role of chemistry and processing conditions

Improvement in oxygen gas barrier properties of polyester/polyamide blends used in packaging industry is the main objective of the present study. For this purpose poly(ethylene terephthalate) (PET)/poly(m-xylene adipamide) (nylon-MXD6) (95/5 w/w) and poly(ethylene terephthalate-co-isophthalate) copolymer (PETI)/MXD6 (95/5 w/w) blends have been prepared with a PET copolymer which consists of 5 wt.% sodium sulfonated isophthalate (PET-co-5SIPA) as compatibilizer and a carboxyl-terminated polybutadiene (CTPB) as filler by using a co-rotating intermeshing twin screw extruder. The effects of chemical architecture and morphology on oxygen gas permeability and processability were analyzed by using a range of characterization techniques including differential scanning calorimetry (DSC), scanning electron microscopy (SEM), oxygen gas permeability analyzer, and a special computer controlled uniaxial stretching system that provides real-time measurement of true stress, true strain and birefringence. The morphological analysis revealed that PET-co-5SIPA was an effective compatibilizer for both PET/MXD6 and PETI/MXD6 blends. DSC analysis and spectral-birefringence technique were used to understand the thermal and stress-induced crystallization behavior of the blends. Morphological analysis of the films after biaxial stretching indicated that the spherical nylon phase was converted to 75 nm thick disks during stretching (aspect ratio L/W = 6) that creates a tortuous pathway for oxygen ingress. Stretching enhanced the barrier properties of PET/MXD6 and PETI/MXD6 blends.     

A Copolymer Scaffold Functionalized with Nanodiamond Particles Enhances Osteogenic Metabolic Activity and Bone Regeneration

Functionalizing polymer scaffolds with nanodiamond particles (nDPs) has pronounced effect on the surface properties, such as improved wettability, an increased active area and binding sites for cellular attachment and adhesion, and increased ability to immobilize biomolecules by physical adsorption. This study aims to evaluate the effect of poly(l ‐lactide‐co‐ε‐caprolactone) (poly(LLA‐co‐CL)) scaffolds, functionalized with nDPs, on bone regeneration in a rat calvarial critical size defect. Poly(LLA‐co‐CL) scaffolds functionalized with nDPs are also compared with pristine scaffolds with reference to albumin adsorption and seeding efficiency of bone marrow stromal cells (BMSCs). Compared with pristine scaffolds, the experimental scaffolds exhibit a reduction in albumin adsorption and a significant increase in the seeding efficiency of BMSCs (p = 0.027). In the calvarial defects implanted with BMSC‐seeded poly(LLA‐co‐CL)/nDPs scaffolds, live imaging at 12 weeks discloses a significant increase in osteogenic metabolic activity (p = 0.016). Microcomputed tomography, confirmed by histological data, reveals a substantial increase in bone volume (p = 0.021). The results show that compared with conventional poly(LLA‐co‐CL) scaffolds those functionalized with nDPs promote osteogenic metabolic activity and mineralization capacity. It is concluded that poly(LLA‐co‐CL) composite matrices functionalized with nDPs enhance osteoconductivity and therefore warrant further study as potential scaffolding material for bone tissue engineering.

     

Synthesis and properties of novel aliphatic poly(carbonate-ester)s

The biodegradable poly(5-methyl-5-methoxycarbonyl-1,3-dioxan-2-one-co-d,l-lactide) [poly(MMTC-co-d,l-LA)] copolymers were synthesized by the ring-opening copolymerization. The results show that the yield and molecular weight of copolymers are significantly influenced by reaction conditions. The chemical structure of the resultant copolymers was characterized by FTIR, ¹H NMR and ¹³C NMR methods. Their molecular weight was measured by gel permeation chromatography (GPC). Study of monomer coreactivity ratios indicates that d,l-LA reacts faster than MMTC in the copolymerization. The enzymatic degradation of the polymers with various compositions was studied at 37 °C in pH = 8.6 Tris-HCl buffer solution in the presence of proteinase K. Their mechanical properties were also preliminarily investigated.     

UV assisted photo reactive polyether-polyesteramide resin for future applications in 3D printing

Among additive manufacturing, photocuring 3D printing technologies are very relevant because of its high printing speed and high precision. However, the limited performance of photosensitive thermoset polymers is the bottleneck for the application of photocuring 3D printing in some fields, particularly in the biomedical sector. Thus, the development of biodegradable and biocompatible materials is highly desirable and of utmost importance. In this work, a biodegradable and non-cytotoxic thermoset polymer for photocuring 3D printing is reported. It consists of an unsaturated polyesteramide bearing phenylalanine, 2-butene-1,4-diol and fumarate building blocks, which is photocured under UV irradiation using a low molecular weight poly(ethylene glycol) diacrylate as crosslinker. The main characteristics of the new thermoset are: (1) very high volumetric and mechanical integrity stabilities, comparable to that of photocured epoxides; (2) very high degradation temperature; (3) very low water absorption capacity; (4) relatively fast enzymatic degradation, reaching 16.5% after 3 months; and (5) non-cytotoxic response in presence of epithelial cells, even when soluble molecular fragments coming from biodegradation are considered. These properties favor the future utilization of the new polyether-polyesteramide resin in the manufacturing of more sustainable products via 3D printing methods, such as stereolithography, that uses UV sources.     

Characterization and enzymatic degradation of microbial copolyester P(3HB-co-3HV)s produced by metabolic reaction model-based system

The two types of poly(3-hydroxybutyrate-co-3-hydroxyvalerate)s [P(3HB-co-3HV)s] were produced by Paracoccus denitrificans ATCC 17741 using two different feeding methods. The produced P(3HB-co-3HV)s were fractionated and the copolymer sequence distributions were analyzed by ¹H and ¹³C NMR spectroscopy. It was found that the P(3HB-co-3HV) samples produced by conventional feeding method were statistically random copolymers. The sequence distributions of P(3HB-co-3HV) samples produced by optimization method were different from random P(3HB-co-3HV)s. The thermal properties and melting behaviors were analyzed by differential scanning calorimetry (DSC). These results demonstrated that P(3HB-co-3HV) samples produced by optimization method are close in nature to P(3HB-co-3HV)s rich in long-sequence of block 3HB units, but less in 3HV random regions. The enzymatic degradation profile of P(3HB-co-3HV) films was investigated in the presence of 3-hydroxybutyrate depolymerase from Pseudomonase lemoignei. The degradation process was observed by monitoring the time-dependent change in the weight loss of copolymer films. The surface erosion of copolymer films was qualitatively monitored by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The highest degradation rate of 2.6% per day was observed for random P(3HB-co-38%3HV) produced by conventional method. In comparison, the hydrolysis degradation rates of random P(3HB-co-3HV)s were about one time faster than those of P(3HB-co-3HV)s produced by optimization method.     

Water‐disintegrative and biodegradable blends containing poly(L‐lactic acid) and poly(butylene adipate‐co‐terephthalate)

In this study, novel biodegradable materials were successfully generated, which have excellent mechanical properties in air during usage and storage, but whose structure easily disintegrates when immersed in water. The materials were prepared by melt blending poly(L ‐lactic acid) (PLLA) and poly(butylene adipate‐co‐terephthalate) (PBAT) with a small amount of oligomeric poly(aspartic acid‐co‐lactide) (PAL) as a degradation accelerator. The degradation behavior of the blends was investigated by immersing the blend films in phosphate‐buffered saline (pH = 7.3) at 40 °C. It was shown that the PAL content and composition significantly affected morphology, mechanical properties, and hydrolysis rate of the blends. It was observed that the blends containing PAL with higher molar ratios of L ‐lactyl [LA]/[Asp] had smaller PBAT domain size, showing better mechanical properties when compared with those containing PAL with lower molar ratios of [LA]/[Asp]. The degradation rates of both PLLA and PBAT components in the ternary blends simultaneously became higher for the blends containing PAL with higher molar ratios of [LA]/[Asp]. It was confirmed that the PLLA component and its decomposed materials efficiently catalyze the hydrolytic degradation of the PBAT component, but by contrast that the PBAT component and its decomposed materials do not catalyze the hydrolytic degradation of the PLLA component in the blends. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2010     

Biodegradable photocrosslinkable poly(depsipeptide‐co‐ε‐caprolactone) for tissue engineering: Synthesis,characterization, and In vitro evaluation

Stereolithography has become increasingly popular in scaffold fabrication due to automation and well‐controlled geometry complexity, and consequently, there is a great need for new suitable biodegradable photocrosslinkable polymers. In this study, a new type of photocrosslinkable poly(ester amide) was synthesized based on ε‐caprolactone and l ‐alanine‐derived depsipeptide and was applied to fabrication of three‐dimensional (3D) scaffolds by stereolithography. ¹H nuclear magnetic resonance and Fourier transform infra‐red analysis confirmed the formation of new bonds during the polymer synthesis. Incorporation of depsipeptide increased the glass transition temperature and hydrophilicity of the polymer and accelerated hydrolytic degradation compared with the poly(ε‐caprolactone) homopolymer. The compressive strength of the 3D scaffolds increased with the increasing depsipeptide content. This work demonstrated that incorporation of depsipeptide into photocrosslinkable polyesters resulted in excellent cytocompatibility and tunable degradation rates and mechanical properties and thus expanded the repertoire of biomaterials suitable for 3D photofabrication of high‐resolution tissue engineering scaffolds. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 3307–3315     

Thermal degradation of poly(lactic acid) (PLA) and poly(butylene adipate-co-terephthalate) (PBAT) and their blends upon melt processing

Poly(lactic acid) (PLA) and poly(butylene adipate-co-terephthalate) (PBAT) are biodegradable aliphatic polyesters, which being semicrystalline and thermoplastic can be processed by conventional methods. Their blends give interesting materials for industrial packaging applications, due to their increased ductility as PBAT content increases. However, like many aliphatic polyesters, the PLA matrix degrades upon melt processing thus affecting the thermo-mechanical features of the blended material. In this work, we studied the effect of processing at high temperature on the molecular weight distribution, morphology, and thermo-mechanical properties of both homopolymers, as well as the PLA/PBAT 75/25 blend. Notably, different processing conditions were adopted in terms of temperature (range 150-200 °C) and other relevant processing parameters (moisture removal and nitrogen atmosphere). Analysis of PLA/PBAT blends indicated that intermolecular chain reactions took place under strong degradative conditions of PLA, yielding PLA/PBAT mixed chains (copolymers). Increasing amounts of copolymers resulted in improved phase dispersion and increased ductility, as SEM and mechanical tests indicated. Conversely, reduced PLA degradation with less copolymer formation, afforded higher modulus materials, owing to poorer dispersion of the soft phase (PBAT) into the PLA matrix.