Homogenization of Mutually Immiscible Polymers Using Nanoscale Effects: A Theoretical Study

4 p.A theoretical study to investigate homogenization of mutually immiscible polymers using nanoscale effects has been performed. Specifically, the miscibility behavior of all-polymer nanocomposites composed of linear-polystyrene (PS) chains and individual cross-linked poly(methyl methacrylate)-nanoparticles (PMMA-NPs) has been predicted. By using a mean field theory accounting for combinatorial interaction energy and nanoparticle-driven effects, phase diagrams were constructed as a function of PMMA-NP size, PS molecular weight, and temperature. Interestingly, complete miscibility (i.e., homogeneity) was predicted from room temperature to 675 K for PMMA-nanoparticles with radius less than ~7 nm blended with PS chains (molecular weight 150 kDa, nanoparticle volume fraction 20%) in spite of the well-known immiscibility between PS and PMMA. Several nanoscale effects affecting miscibility in PMMA-NP/PS nanocomposites involving small PMMA-nanoparticles are discussed.Financial support by MEC (Grant no. CSD2006-53), Basque Government (Grupos Consolidados IT-274-07), and Diputación de Gipuzkoa through C. I. C. Nanogune—Consolider and Nanotron Project is gratefully acknowledged

Poli(butilen adipato-ko-tereftalato)/Fenoxi sistemaren nahaskortasuna eta hesi-propietateen aldaketa

Biodegradable and compostable Poly(butylene adipate-co-terephthalate) (PBAT) copolymer has been stud ied. lt has good mechanical properties, but in order to be used in industrial appl ications its barrier properties must be improved significant ly.For this purpose it has been mixed with phenoxy resin. Miscibility is established through determ ination of the glass transition temperature. The relationship between the T~ and composition has been stud ied using different models, since th is re lat ionship reflects the strength of the interactions. Water vapou r and oxygen permeability ha ve been measured to determine transpon properties. The results indicare that the PBAT/Ph system is miscib le o ver the en tire composition range. The analysis of the transport properties results shows that the addition of phenoxy causes a sharp decrease in water vapour and oxygen permeability, wh ich is beneficia! for industrial applications .; Biodegradagarria eta konpostagarria den kopol imero bat aztertu da, poli( butilen adipato-ko-tereftalatoa) (PBAT) hain zuzen ere. Propietate mekaniko egokiak dituen arren , aplikazio industrialetan erabilgarria izan dad in bere hesi-propietateak nabarmen hobetu behar dira. Helburu hori lortu nahian, fenoxi erretxinarekin (Ph) nahastu da . Sistemaren nahaskortasuna karakterizatu da beira-trantsizioaren tenperatura zehaztuz . T~-ak konpos izioaren arabera jasaten duen aldaketa azaltzeko badaude hainbat eredu teoriko , nahastea osatzen duten bi osagaien arteko elkarrekintzen isla direnak.Ondoren, ur-lurrunarekiko eta oxigenoarekiko iragazkortasuna neurtu da sistemaren hesi-propietateak zehazteko. Lorturiko emaitzek aditzera eman dutenez PBAT/ Ph sistema nahaskorra da azterturiko konposizio guztietan. Hesi-propietateen emaitzak aztertuz. ikusi da fenoxiaren gehikuntzak ur-lurrunarekiko zein oxigenoarekiko iragazkortasunaren jaitsiera esangurats ua dakarrela; ahalmen hori baliagarria izan daiteke material hau industrian erabiltzeko unean

Lactide and Ethylene Brassylate-Based Thermoplastic Elastomers and Their Nanocomposites with Carbon Nanotubes: Synthesis, Mechanical Properties and Interaction with Astrocytes

Polylactide (PLA) is among the most commonly used polymers for biomedical applications thanks to its biodegradability and cytocompatibility. However, its inherent stiffness and brittleness are clearly inappropriate for the regeneration of soft tissues (e.g., neural tissue), which demands biomaterials with soft and elastomeric behavior capable of resembling the mechanical properties of the native tissue. In this work, both L- and D,L-lactide were copolymerized with ethylene brassylate, a macrolactone that represents a promising alternative to previously studied comonomers (e.g., caprolactone) due to its natural origin. The resulting copolymers showed an elastomeric behavior characterized by relatively low Young’s modulus, high elongation at break and high strain recovery capacity. The thermoplastic nature of the resulting copolymers allows the incorporation of nanofillers (i.e., carbon nanotubes) that further enable the modulation of their mechanical properties. Additionally, nanostructured scaffolds were easily fabricated through a thermo-pressing process with the aid of a commercially available silicon stamp, providing geometrical cues for the adhesion and elongation of cells representative of the nervous system (i.e., astrocytes). Accordingly, the lactide and ethylene brassylate-based copolymers synthesized herein represent an interesting formulation for the development of polymeric scaffolds intended to be used in the regeneration of soft tissues, thanks to their adjustable mechanical properties, thermoplastic nature and observed cytocompatibility.Grant PID2019-106236GB-I00 funded by MCIN/AEI/10.13039/501100011033. The authors are also thankful for funds from the Basque Government, Department of Education (IT-1766-22). C.B.-Á.: acknowledges the predoctoral grant funded by the UPV/EHU. Polimerbio and Y.P. have a Bikaintek Ph.D. grant (20-AF-W2-2018-00001)

Experimentación en Química Física

Nivel educativo: Grado. Duración (en horas): Más de 50 horasExperimentación en Química Física es una asignatura de carácter experimental que introduce a los estudiantes en la utilización de algunos métodos instrumentales para la determinación de propiedades macroscópicas ligadas a la Química Física. Se trata de una asignatura anual, si bien la implantación de la metodología ABP se ha realizado en los experimentos que se realizan durante el primer cuatrimestre. Para implantar la metodología ABP se ha elegido un problema estructurante lo suficientemente genérico para permitir adaptarlo a las distintas experiencias que se realizan en el laboratorio. Dado que en el laboratorio se dispone de un determinado equipamiento, se han adecuado los distintos problemas a las disponibilidades actuales del laboratorio

Polilaktida plastifikatua elikagaien ontziratzerako: plastifikatzailearen pisu molekularraren eragina bolumen aske eta hesi-ezaugarrietan

Nowadays the main strategy to solve the problem of plastic waste is to use biodegradable polymers. Among them, polylactide has attracted a great attention. However in order to be suitable for packaging applications its ductility must be improved. With this aim, polylactide has been blended with polyethylene glycol (PEG). More exactly, three different polyethylene glycols have been used and the effect of the molecular weight on the physical properties has been analysed. The addition of the plasticizer reduces the glass transition temperature, especially the polyethylene glycol with the highest molecular weight, and the crystallinity level is increased. The changes in the free volume fraction are small but with high plasticizer content the free volume fraction increases considerably. Regarding the barrier character, the oxygen permeability is reduced or maintained, whereas carbon dioxide and water permeability increase with the addition of the plasticizer. It is worthy to note that among the blends containing different plasticizers, the system containing the plasticizer with the lowest molecular weight shows the highest permeability values. In the case of systems containing PEG 1500 and PEG 4600 the changes are subtle and apart from the molecular weight, other factors such as the glass transition temperature, the degree of crystallinity and the free volume influence the transport properties.; Gaur egun plastikoen hondakinek sorrarazten duten arazoari aurre egiteko aukera bat polimero biodegradagarriak erabiltzea da. Horien artean polilaktidak interes handia piztu du, baina elikagaien ontziratzean erabilgarria izan dadin bere deformakortasuna hobetu behar da. Helburu horrekin lan honetan polilaktidari polietilenglikol (PEG) plastifikatzailea gehitu zaio. Zehazki pisu molekular desberdina daukaten hiru polietilenglikol erabili dira, eta pisu molekularrak propietate fisikoetan daukan eragina aztertu da. Plastifikatzailea gehitutakoan beira-trantsizio tenperatura jaitsi egiten da, bereziki pisu molekular altuena duen polietilenglikola gehitutakoan, eta kristalinitate-maila handiagoa egiten da. Bolumen askean aldaketak txikiak badira ere, plastifikatzaile kantitatea handitu ahala, bolumen askea nabarmen handiagoa egiten da. Hesi ezaugarriei dagokienez, oxigenoaren kasuan iragazkortasuna murriztu edo bere horretan mantentzen da; karbono dioxidoaren eta uraren kasuan, ordea, iragazkortasuna handitu egiten da plastifikatzaile kantitatearekin batera. Aipatzekoa da plastifikatzaile nahaste desberdinen artean pisu molekular baxueneko plastifikatzailea duen sistemak azaltzen dituela iragazkortasun balio altuenak. PEG 1500 eta PEG 4600 sistemen kasuan aldaketak ez dira hain nabariak, eta, pisu molekularraz gainera, beste faktore batzuek, hala nola beira-trantsizio tenperaturak, kristalinitate-mailak eta bolumen askeak, ere eragina daukate

Isomorphic polyoxyalkylenes copolyethers obtained by copolymerization of aliphatic diols

Isomorphism in random copolymers occurs when comonomer units can crystallize within a single crystalline lattice in the entire composition range. This ideal behavior is rare in random copolymers and only a few examples of isomorphism are found in copolyesters and copolycarbonates. In this work, we show a series of polyoxyalkylenes copolyethers obtained by copolymerization of 1,6-hexanediol and 1,12-dodecanediol which are able to crystallize in the entire composition range and display an isomorphic behavior. The copolymers were synthesized via a bulk self-condensation method at high temperature, using a thermally stable Non-Eutectic Mixture Organocatalyst (NEMO) prepared from methanesulfonic acid (MSA) and 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD). The final molar ratios of the copolyethers were calculated by 1H NMR spectroscopy and the random distribution of the two monomeric units was confirmed by 13C NMR spectroscopy. The effect of the composition of comonomer units on the crystalline structure was investigated by DSC and WAXS. The two comonomeric units along the chain can co-crystallize regardless of the composition, while displaying melting point values that vary linearly in between those of the parent homopolymers (54,9 and 84,7 °C). The crystalline reflections given by WAXS demonstrated that the two comonomers are miscible in the crystalline state and meet the general criteria to be regarded isomorphic random copolymers. Finally, a random terpolymer was synthetized from 1,6-hexanediol, 1,10-decanediol and 1,12-dodecanediol, which also shows a single melting temperature, thus demonstrating the versatility of the polymerization route employed.The authors thank the European Commission for its financial support through the projects SUSPOL-EJD 642671. Haritz Sardon and David Mecerreyes gratefully acknowledge financial support from MINECO through project POLYCE. A. J. Müller, O. Coulembier and H. Sardon also acknowledge European funding by the RISE BIODEST project (H2020-MSCA-RISE-2017-778092). The authors also thank the technical and human support provided by Mrs. Sofia Guezala (SGIker) of UPV/EHU for the NMR analysis. H. Sardon, A.J. Müller and I. Flores acknowledge funding and beam time from ALBA Synchrotron facility through the project: 2017092338 (2018). A. J. Müller gratefully acknowledges financial support from MINECO through project MAT2017-83014-C2-1-P. A. Etxeberria acknowledges financial support from the Basque Government (GIC IT-618-13). O. C. is Research Associate for the F.R.S.-FNRS. Irma Flores would like to acknowledge Conacyt (Mexico) for supporting her PhD studies with a scholarship

Lactide-Valerolactone Copolymers for Packaging Applications

Lactide-valerolactone copolymers have potential application in the packaging sector. Different copolymers were synthesized, and the kinetics of the copolymerization reactions and the microstructure of the copolymers were analysed. Lactide showed higher reactivity than valerolactone which leads to composition drift through the reaction. Thermal, mechanical and barrier properties of the selected copolymers were studied. Overall, the incorporation of valerolactone results in copolymers with higher ductility than poly(lactide) with intermediate water and oxygen permeability which makes these materials appropriate candidates for use in the packaging sector.The financial support from the Basque Government (GC IT-1313-19, PPGA 19/18 and GIU 19/077) and the Spanish Ministry of Innovation and Competitiveness MINECO (PID2019-106236GB-I00) is acknowledged. A. Sangroniz thanks the Basque Government for the PhD grant. L. Sangroniz thanks the Basque Government for the postdoctoral fellowship (POSDOC). S. Hamzehlou acknowledges the University of the Basque Country (UPV/EHU) for the “Contratación para la especialización de personal investigador doctor” postdoctoral grant. The authors thank the technical and human support provided by Sofia Guezala (NMR SGIker) and European Funding (ERDF and ESF)

Enantioselective Ring-Opening Polymerization of rac-Lactide Dictated by Densely Substituted Aminoacids

Organocatalysis is becoming an important tool in polymer science because of its versatility and specificity. To date a limited number of organic catalysts have demonstrated the ability to promote stereocontrolled polymerizations. In this work we report one of the first examples of chirality transfer from a catalyst to a polymer in the organocatalyzed ring-opening polymerization (ROP) of rac-lactide (rac-LA). We have polymerized rac-LA using the diastereomeric densely substituted amino acids (2S,3R,4S,5S)-1-methyl-4-nitro-3,5-diphenylpyrrolidine- 2-carboxylic acid (endo-6) and (2S,3S,4R,5S)-1-methyl-4- nitro-3,5-diphenylpyrrolidine-2-carboxylic acid (exo-6), combined with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as a cocatalyst. Both diastereoisomers not only showed the ability to synthesize enriched isotactic polylactide with a Pm higher than 0.90 at room temperature but also were able to preferentially promote the polymerization of one of the isomers (L or D) with respect to the other. Thus, exo-6 preferentially polymerized Llactide, whereas endo-6 preferred D-lactide as the substrate. Density functional theory calculations were conducted to investigate the origins of this unique stereocontrol in the polymerization, providing mechanistic insight and explaining why the chirality of the catalyst is able to define the stereochemistry of the monomer insertion.Financial support of this research by the MINECO (CTQ2016-80375-P, Consolider CTQ2016-81797-REDC, SUSPOL, and FDI 16507), the Gobierno Vasco/Eusko Jaurlaritza (Grants IT673-13 and IT618-13), the University of the Basque Country UPV/EHU (UFI 11/22 QOSYC), and the European Commission (SUPSOL-EJD 642671) is gratefully acknowledged. A.S.-S. is thankful for the Postdoctoral Funding for Doctoral Research Staff Improvement Grant from the Basque Government

Miscibility and Hydrogen Bonding in Blends of Poly(4-vinylphenol)/Poly(vinyl methyl ketone)

The miscibility and phase behavior of poly(4-vinylphenol) (PVPh) with poly(vinyl methyl ketone) (PVMK) was investigated by differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). It was shown that all blends of PVPh/PVMK are totally miscible. A DSC study showed the apparition of a single glass transition (T-g) over their entire composition range. When the amount of PVPh exceeds 50% in blends, the obtained T(g)s are found to be significantly higher than those observed for each individual component of the mixture, indicating that these blends are capable of forming interpolymer complexes. FTIR analysis revealed the existence of preferential specific interactions via hydrogen bonding between the hydroxyl and carbonyl groups, which intensified when the amount of PVPh was increased in blends. Furthermore, the quantitative FTIR study carried out for PVPh/PVMK blends was also performed for the vinylphenol (VPh) and vinyl methyl ketone (VMK) functional groups. These results were also established by scanning electron microscopy study (SEM).The authors would like to acknowledge the financial support from the Basque Government (IT618-13) and Basque Country University (UFI 11/56)