Editorial Special Issue: "Advance Polymeric Materials: Synthesis, Properties and Applications"

As a consequence of their properties of lightness, strength, versatility, low toxicity, low cost and durability, the 20th century saw the beginning of the use of polymers as disruptive materials [...

Controlling the Isothermal Crystallization of Isodimorphic PBS-ran-PCL Random Copolymers by Varying Composition and Supercooling

In this work, we study for the first time, the isothermal crystallization behavior of isodimorphic random poly(butylene succinate)-ran-poly(ε-caprolactone) copolyesters, PBS-ran-PCL, previously synthesized by us. We perform nucleation and spherulitic growth kinetics by polarized light optical microscopy (PLOM) and overall isothermal crystallization kinetics by differential scanning calorimetry (DSC). Selected samples were also studied by real-time wide angle X-ray diffraction (WAXS). Under isothermal conditions, only the PBS-rich phase or the PCL-rich phase could crystallize as long as the composition was away from the pseudo-eutectic point. In comparison with the parent homopolymers, as comonomer content increased, both PBS-rich and PCL-rich phases nucleated much faster, but their spherulitic growth rates were much slower. Therefore, the overall crystallization kinetics was a strong function of composition and supercooling. The only copolymer with the eutectic composition exhibited a remarkable behavior. By tuning the crystallization temperature, this copolyester could form either a single crystalline phase or both phases, with remarkably different thermal properties.Funding: This research was funded by (a) MINECO through project MAT2017-83014-C2-1-P, (b) ALBA synchrotron facility through granted proposal 2018082953 (c) the Basque Government through grant IT1309-19 and (d) European Union´s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 778092 Acknowledgments: MS gratefully acknowledges the award of a PhD fellowship by POLYMAT Basque Center for Macromolecular Design and Engineering

Influence of chain topology (cyclic versus linear) on the nucleation and isothermal crystallization of poly(L-lactide) and poly(D-lactide)

In this paper, ring closure click chemistry methods have been used to produce cyclic c-PLLA and c-PDLA of a number average molecular weight close to 10 kg/mol. The effects of stereochemistry of the polymer chains and their topology on their structure, nucleation and crystallization were studied in detail employing Wide Angle X-ray Scattering (WAXS), Small Angle X-ray Scattering (SAXS), Polarized Light Optical Microscopy (PLOM) and standard and advanced Differential Scanning Calorimetry (DSC). The crystal structures of linear and cyclic PLAs are identical to each other and no differences in superstructural morphology could be detected. Cyclic PLA chains are able to nucleate much faster and to produce a higher number of nuclei in comparison to linear analogues, either upon cooling from the melt or upon heating from the glassy state. In the samples prepared in this work, a small fraction of linear or higher molecular weight cycles was detected (according to SEC analyses). The presence of such “impurities” retards spherulitic growth rates of c-PLAs making them nearly the same as those of l-PLAs. On the other hand, the overall crystallization rate determined by DSC was much larger for c-PLAs, as a consequence of the enhanced nucleation that occurs in cyclic chains. The equilibrium melting temperatures of cyclic chains were determined and found to be 5 ºC higher in comparison with values for l-PLAs. This result is a consequence of the lower entropy of cyclic chains in the melt. Self-nucleation studies demonstrated that c-PLAs have a shorter crystalline memory than linear analogues, as a result of their lower entanglement density. Successive self-nucleation and annealing (SSA) experiments reveal the remarkable ability of cyclic molecules to thicken, even to the point of crystallization with extended collapsed ring conformations. In general terms, stereochemistry had less influence on the results obtained in comparison with the dominating effect of chain topology.“UPV/EHU Infrastructure: INF 14/38”; “Mineco/FEDER: SINF 130I001726XV1/Ref: UNPV13–4E–1726” and “Mineco MAT2014-53437-C2-P”, 'Ministerio de Economia y Competitividad (MINECO), code: MAT2015-63704-P (MINECO/FEDER, UE) and by the Eusko Jaurlaritza (Basque Government), code: IT-654-13. O.C acknowledges financial support from the European Commission and Région Wallonne FEDER program (Materia Nova) and OPTI²MAT program of excellence, by the Interuniversity Attraction Pole Program (P7/05) initiated by the Belgian Science Policy office and by the FNRS-FRFC. OC is Research Associate of the F.R.S.-FNRS. Organic Synthesis and Mass Spectrometry Laboratory thanks F.R.S.-FNRS for the financial support for the acquisition of the Waters QToF Premier and Synapt-G2Si mass spectrometers and for continuing support. Finally, all authors would like to acknowledge Research and Innovation Staff Exchange (RISE) H2020-MSCA-RISE-2017-778092, project BIODEST for promoting cooperation between the Mons team and the UPV/EHU team

Crystallization and Morphology of Triple Crystalline Polyethylene-b-poly(ethylene oxide)-b-poly(ε-caprolactone) PE-b-PEO-b-PCL Triblock Terpolymers

The morphology and crystallization behavior of two triblock terpolymers of polymethylene, equivalent to polyethylene (PE), poly (ethylene oxide) (PEO), and poly (ε-caprolactone) (PCL) are studied: PE227.1-b-PEO4615.1-b-PCL3210.4 (T1) and PE379.5-b-PEO348.8-b-PCL297.6 (T2) (superscripts give number average molecular weights in kg/mol and subscripts composition in wt %). The three blocks are potentially crystallizable, and the triple crystalline nature of the samples is investigated. Polyhomologation (C1 polymerization), ring-opening polymerization, and catalyst-switch strategies were combined to synthesize the triblock terpolymers. In addition, the corresponding PE-b-PEO diblock copolymers and PE homopolymers were also analyzed. The crystallization sequence of the blocks was determined via three independent but complementary techniques: differential scanning calorimetry (DSC), in situ SAXS/WAXS (small angle X-ray scattering/wide angle X-ray scattering), and polarized light optical microscopy (PLOM). The two terpolymers (T1 and T2) are weakly phase segregated in the melt according to SAXS. DSC and WAXS results demonstrate that in both triblock terpolymers the crystallization process starts with the PE block, continues with the PCL block, and ends with the PEO block. Hence triple crystalline materials are obtained. The crystallization of the PCL and the PEO block is coincident (i.e., it overlaps); however, WAXS and PLOM experiments can identify both transitions. In addition, PLOM shows a spherulitic morphology for the PE homopolymer and the T1 precursor diblock copolymer, while the other systems appear as non-spherulitic or microspherulitic at the last stage of the crystallization process. The complicated crystallization of tricrystalline triblock terpolymers can only be fully grasped when DSC, WAXS, and PLOM experiments are combined. This knowledge is fundamental to tailor the properties of these complex but fascinating materials.This research received funding from MINECO through projects MAT2017-83014-C2-1-P, from the Basque Government through grant IT1309-19, and from ALBA synchrotron facility through granted proposal u2020084441 (March 2020). We would like to thank the financial support provided by the BIODEST project; this project has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement no. 778092. GZ, VL, and NH wish to acknowledge the support of KAUST

Influence of chain topology on gel formation and direct ink printing of model linear and star block copolymers with poly(ethylene oxide) and poly(ε-caprolactone) semi-crystalline blocks

In this work, a set of well-defined linear triblock copolymers and star block copolymers (3 and 4-arms) with semi crystalline blocks consisting of poly(ethylene oxide) (PEO) and poly(epsilon-caprolactone) (PCL), synthesized by combining ring-opening polymerization and organic catalyst switch strategy, were studied as thermosensitive gel-forming biomaterials for applications in 3D extrusion printing. The hydrogels derived from linear copolymers underwent a temperature-dependent sol-gel-sol transition, behaving as a flowing sol at room temperature and transforming into a non-flowing gel upon heating. On the other hand, the hydrogels derived from 4-arm star block copolymers experienced a gel-sol transition and did not flow at room temperature. This behavior allowed them to be used as 3D printing inks at room temperature. 3D printing results revealed that the semi-crystalline hydrogels of the 4-arm star block copolymers could not only be extruded and printed with high shape fidelity, but they also exhibited a favorable dissolution profile for their use as sacrificial biomaterial inks. Additionally, we thoroughly investigated the crystalline organization of the PCL and the PEO blocks within the hydrogels through comparison with the results obtained in bulk. The results demonstrated evident structural ordering in the hydrogels associated with the crystallization of the PCL blocks. Unexpectedly, DSC results combined with SAXS experiments revealed the presence of PEO block crystals within the 30 % w/v hydrogels from 4-arm star block copolymers, in addition to the PCL block crystals. Hence, remarkable double crystalline hydrogels have been obtained for the first time.This research was financially supported by the projects PID2020-113045GB-C21 and PID2020-113045GB-C22 funded by MCIN/ AEI /10.13039/501100011033 and by the Basque Government through grant IT1503-22. M.I.P. acknowledges funding through an FPI contract (PRE2018-086104) to develop a PhD thesis. The support of the ALBA (2022086944 and 2022086957 proposals) synchrotron facility is gratefully acknowledged. R.H. is a member of the CSIC Interdisciplinary Thematic Platform (PTI+) Interdisciplinary Platform for Sustainable Plastics towards a Circular Economy+ (PTI-SusPlast+) and the PTI CSIC FAB3D. The authors would also like to thank Alejandro Hernandez-Sosa for assistance regarding 3D printing experiments. P.Z., V.L., and N.H. gratefully acknowledge the support of the King Abdullah University of Science and Technology (KAUST)

Supernucleation Dominates Lignin/Poly(ethylene oxide) Crystallization Kinetics

The effect of lignin nanoparticles (LNPs) on the crystallization kinetics of poly(ethylene oxide) (PEO) is examined. Lignin from spruce and ionic isolation was used to prepare LNPs with a number-averaged diameter of 85 nm (with a relatively large polydispersity) by an ultrasonication method. PEO-based nanocomposites with four different LNP contents (5, 10, 15, and 20 wt %) were prepared and subject to isothermal and nonisothermal crystallization protocols in a series of experiments. Scanning electron microscopy (SEM) images showed well-dispersed LNPs in the crystallized PEO matrix. The incorporation of LNPs exponentially increases nucleation density at moderate loadings, with this trend apparently saturating at higher loadings. However, the spherulitic growth rate decreases monotonically with LNP loading. This is attributed to the substantial PEO/LNP affinity, which impacts chain diffusion and induces supernucleation effect (with efficiencies in the order of 200%), but leads to slower growth rates. The overall crystallization kinetics, measured by the DSC, shows faster nanocomposite crystallization rates relative to the neat PEO at all LNP contents examined. This indicates that the supernucleation effect of LNPs dominates over the decrease in the growth rates, although its influence slightly decreases as the LNP content increases. The strong hydrogen-bonded interactions between the LNPs and the PEO are thus reminiscent of confinement effects found in polymer-grafted NP nanocomposites (e.g., PEO-g-SiO2/PEO) in the brush-controlled regime.This work received funding from the Basque Government through grant IT1503 - 22. S.K.K . acknowledges funding by the U.S. Department of Energy, Office of Science, grants DE- SC0018182, DE-SC0018135, and DE-SC0018111. The authors acknowledged the financial support of Fundacion Losano, PIP2011 848, and PUE No. 22920160100007 (CONICET) . The authors acknowledge the support of Ana Martínez Amesti, Microscopy: Polymer Characterization Research Service, SGIker (UPV/EHU)

Structure and Properties of Reactively Extruded Opaque Post-Consumer Recycled PET

The recyclability of opaque PET, which contains TiO2 nanoparticles, has not been as well-studied as that of transparent PET. The objective of this work is to recycle post-consumer opaque PET through reactive extrusion with Joncryl. The effect of the reactive extrusion process on the molecular structure and on the thermal/mechanical/rheological properties of recycling post-consumer opaque PET (r-PET) has been analyzed. A 1% w/w Joncryl addition caused a moderate increase in the molecular weight. A moderate increase in chain length could not explain a decrease in the overall crystallization rate. This result is probably due to the presence of branches interrupting the crystallizable sequences in reactive extruded r-PET (REX-r-PET). A rheological investigation performed by SAOS/LAOS/elongational studies detected important structural modifications in REX-r-PET with respect to linear r-PET or a reference virgin PET. REX-r-PET is characterized by a slow relaxation process with enlarged elastic behaviors that are characteristic of a long-chain branched material. The mechanical properties of REX-r-PET increased because of the addition of the chain extender without a significant loss of elongation at the break. The reactive extrusion process is a suitable way to recycle opaque PET into a material with enhanced rheological properties (thanks to the production of a chain extension and long-chain branches) with mechanical properties that are comparable to those of a typical virgin PET sample.We would like to acknowledge funding by the EU Interreg H2020 program through project POCTEFA EFA329/19. This work also received funding from the Basque Government, grant IT1309-19

Biodegradable binary blends of poly (butylene succinate) or poly (ε-caprolactone) with poly (butylene succinate-ran-ε-caprolactone) copolymers: Crystallization behavior

Unformatted preprint version of the submitted article.Poly (butylene succinate) (PBS) and polycaprolactone (PCL) are two immiscible biocompatible and biodegradable polymers. Aiming to combine the properties of these biodegradable polymers, this work explores for the first time blending PBS or PCL with PBS-ran-PCL copolymers (BSxCLy) at 75/25, 50/50, and 25/75 wt% compositions, with various copolymer contents: BS78CL22, BS46CL54, and BS15CL85. The crystallization behavior of these novel binary blends was systematically studied with non-isothermal and isothermal differential scanning calorimetry (DSC), polarized light optical microscopy (PLOM), and simultaneous wide- and small-angle X-ray scattering (WAXS and SAXS). All the blends displayed a miscible character in the amorphous state, judging by a single glass transition temperature, and in the melt state (as indicated by SAXS), but their miscibility in the crystalline state depends on the specific blend. In both PBS/BS78CL22 and PCL/BS15CL85 evidences of co-crystallization between the matrix and the crystallizable fraction of the copolymer were found. However, high comonomer exclusion, higher in the BS15CL85 than in the BS78CL22, greatly affects blend miscibility. Thus, the results show that the PBS/BS78CL22 blend is miscible, in the crystalline state, at high PBS (homopolymer) content, i.e., 75/25 and 50/50 compositions, whereas its “counterpart”, the PCL/BS15CL85 displays partial miscibility, even for high PCL (homopolymer) content. For the 25/75 blends, i.e., copolymer-rich, the homopolymer addition favors the crystallization of the copolymer-rich component. Blending PBS or PCL with BS46CL54 leads to blends that exhibit a much lower miscibility in the crystalline state than the blends prepared with BS or CL-rich copolymers, independently of the composition. But, interestingly, a novel behavior is found, since the BS46CL54 copolymer can crystallize either in PBS type crystals or in PCL type crystals depending on the polymeric matrix (PCL or PBS). The PBS favors the crystallization of the BS component, while the PCL favors the crystallization of the CL component within the random copolymer. The crystallization behavior found in this work evidences the interactions of the PBS or PCL with the BSxCLy copolymer, representing a potential strategy to combine the properties of the PBS and PCL through blending.This work has received funding from the Basque Government through grant IT1503-22. This work was also supported by the National Key R&D Program of China (2017YFE0117800) and the National Natural Science Foundation of China (21922308, 51820105005). We would also like to acknowledge the financial support from the BIODEST project; this project has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No. 778092. We would also like to acknowledge the financial support of the Spanish Ministry of Science and Innovation (MICINN) through grant PID2020-113045GB-C21. G.L. is grateful to the Youth Innovation Promotion Association of the Chinese Academy of Sciences (Y201908). The authors thank the ALBA synchrotron fund (2020024169), facilities and staff

Tailoring the isothermal crystallization kinetics of isodimorphic poly (butylene succinate-ran-butylene azelate) random copolymers by changing composition

A detailed isothermal crystallization study of biobased and biodegradable isodimorphic poly (butylene succinate-ran-butylene azelate) random copolyesters (PBS-ran-PBAz) with a wide composition range has been carried out to determine nucleation kinetics, spherulitic growth rates and overall crystallization kinetics. Differential Scanning Calorimetry (DSC) and Polarized Light Optical Microscopy (PLOM) analysis show that for the PBS-rich phase, the incorporation of BAz comonomer leads to a significant increase in nucleation density and a decrease in spherulitic growth. On the contrary, for the PBAz-rich phase, an antinucleating effect of the incorporation of BS comonomer has been observed. Both effects agree with the thermodynamic analysis of the equilibrium melting point depression as a function of composition, which predicts that only a small amount of BAz comonomer is included within the PBS-rich crystals and a larger amount of comonomer is included in PBAz-rich crystals. In addition, the enthalpy of melting of 100% crystalline PBS and PBAz were determined by a different practical approach: extrapolating real time synchrotron Wide Angle X-ray Scattering (WAXS) isothermal crystallization data and isothermal DSC data.I.A. gratefully acknowledges the award of a PhD fellowship by UPV/EHU. J.M. acknowledges support from the Provincial Council of Gipuzkoa under the program Fellow Gipuzkoa. R.M and Ph.D. thank the Belgian Federal Government Office of Science Policy (SSTC- PAI 6/27) for general support and are much indebted to both Wallonia and the European Commission “FSE and FEDER” for financial support in the frame of SYNOPLISS-POLYTISS and LCFM-BIOMAT projects. The POLYMAT/UPV/EHU team would like to acknowledge funding from MINECO through project: MAT2017-83014-C2-1-P, and from ALBA synchrotron facility through granted proposal 2018022683. Finally, we also acknowledge funding by the European Union′s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 778092