Thin polymer films based on poly(vinyl alcohol) containing graphene oxide and reduced graphene oxide with functional properties

10 pags., 7 figs., 2 tabs.In this article, the effect of the addition of graphene oxide (GO) and reduced graphene oxide (rGO) on the mechanical properties, thermal stability, and electrical conductivity of polyvinyl alcohol (PVA) has been investigated. Different weight percentages of nanofillers ranging from 0.5 to 5 wt% have been combined with PVA. The ultrasonic technique has been applied to disperse nanofillers in the PVA solution. The nanocomposite films have been prepared via solution casting technique and the dispersion of nanofillers into the PVA has been studied through optical microscopy. The microstructure, crystallization behavior, and interfacial interaction were characterized through X-ray diffraction and Fourier transform infrared spectroscopy. Differential scanning calorimetry (DSC) and thermogravimetric analysis have been applied to study the thermal properties of the prepared nanocomposites. The DSC results revealed that the crystallization temperature and melting temperature were enhanced in the presence of GO nanofiller. Besides, the tensile strength at break was improved along with the addition of GO; however, elongation at break for PVA/GO and PVA/rGO was diminished. Moreover, all specimens showed insulating behavior and the only sample was electrically conducting, which contain a high amount of rGO (5 wt%).Spanish Ministry of Science and Innovation, Grant/Award Number:PID2019-107514GB-I0

Is the sub-glass temperature relaxation of furan-based polymers related to their high gas barrier properties?

11th Conference on Broadband Dielectric Spectroscopy and its Applications (BDS2022), Donostia/San Sebastián, 04.Sep - 09.Sep 2022. -- Presentación con 25 diapositivasPoly(alkylene 2,5-furanoate)s, (PAF)s, are fully biobased homopolyesters based on 2,5-furandicarboxylic acid that have recently emerged as promising alternative to petroleum based poly(alkylene terephthalate)s. In addition to a lower production carbon footprint poly(alkylene 2,5-furanoate)s have received significant attention due to their outstanding gas barrier properties in comparison to traditional poly aromatic esters [1]. The influence of chain dynamics on barrier properties has also devoted some attention. Dielectric spectroscopy experiments performed in poly(trimethylene 2,5-furanoate) revealed that the subambient relaxation, below its glass transition temperature, exhibited an inhibition of the mode corresponding to the ester oxygen linked to the aliphatic subunit which efficiently relaxes in the poly(trimethylene terephthalate) counterpart [2]. Fourier Transform Infrared (FT-IR) spectroscopy can provide precise information of intra-molecular motions at the molecular level [3]. By evaluating the vibrational frequencies and the corresponding oscillator, strength from the IR spectra information about the intra-molecular dynamics can be available. In this study, we present a combined IR spectroscopy and BDS study focused on the sub-glass temperature molecular dynamics of poly(trimethylene 2,5-furanoate) in comparison to that of poly(trimethylene terephthalate) in order to shed light on the influence the dynamics on the barrier properties of Poly(alkylene 2,5-furanoate)s.The authors gratefully acknowledge the financial support of the Spanish Ministry of Science and Innovation (MICINN) through PID2019-107514GB-I00 / AEI / 10.13039/501100011033

Inter and intra molecular dynamics in poly(trimethylene 2,5-furanoate) as revealed by infrared and Broadband Dielectric Spectroscopies

9 pags., 9 figs., 2 tabs.Infrared spectroscopy (IR) and Broadband Dielectric Spectroscopy (BDS) experiments have been performed in poly(trimethylene 2,5-furanoate)(PTF) and poly(trimethylene terephthalate)(PTT) below their glass transition temperatures. The BDS experiments reveal a richer inter-molecular dynamic for PTT as characterized by a multimodal β relaxation in contrast with the monomodal one exhibited by PTF. The evolution with temperature of comparable IR absorption bands is very similar for PTF and PTT and shows small shifts in wavenumbers towards lower values, with exception of the band related to the stretching mode of the carbonyl group. In addition, a significant difference appears in the shape of the bands associated with the –C[dbnd]O stretching. While for PTT the absorption feature is comprised of a single component, that for PTF exhibits several components suggesting the presence of hydrogen bonds. This effect may be responsible for the monomodal shape of the β relaxation of PTF since a higher degree of intramolecular coupling between the furan ring and the rest of the monomer is expected. Density Functional Theory (DFT) calculations support the experimental results revealing that as temperature increases an increment of the syn conformations of the 2,5-furandicarboxylic acid (FDCA) moiety is likely to occur in the amorphous state. The energy gain from more stable anti to less stable syn isomers can be compensated by the formation of hydrogen bonds between interchain FDCA moieties in syn conformations. This effect may cause additional hindrance to the intermolecular dynamics of the dielectric β relaxation. It is conceivable that the hindrance exhibited by PTF in both intra and inter-molecular dynamics may play a role in the reduction of gas diffusion and permeability of PTF in comparison with PTT.Grants PID2019-107514 GB-I00/AEI/10.13039/501100011033 and PID2019-106125 GB-I00/AEI/10.13039/501100011033 funded by MCIN/AEI/10.13039/501100011033 and by “ ERDF A way of making Europe”. GS acknowledges grant RYC2020-029810-I funded by MCIN/ AEI/10.13039/501100011033 and by “ ESF Investing in your future”. SP would like to thank for financial support from the National Science Centre within project SONATA no 2018/31/D/ST8/00792.

The study of interactions between the positively charged polymers and insulin in aqueous solutions

Niniejsza praca została poświęcona badaniu oddziaływań pomiędzy insuliną a wybranymi polimerami modyfikowanymi kationowo: dekstranem, chitozanem, hydroksypropylocelulozą oraz polichlorowodorkiem alliloaminy (PAH). Opisano typy preparatów insulinowych. Naszkicowano problem dotyczący alergii na insulinę za którą odpowiedzialne są substancje dodatkowe zawarte w jej preparatach, szczególnie protamina. Podjęto próby opracowania nowych bezpieczniejszych preparatów insuliny o przedłużonym działaniu z zastosowaniem biozgodnych polimerów modyfikowanych kationowo. Posiadają one podobnie jak protamina ładunek dodatni i tak samo jak ona mogą poprzez tworzenie kompleksów wpływać na aktywność innych biopolimerów. Wykazano, że w układach złożonych z insuliny z PAH modyfikowanym argininą (ARG) powstają duże, stabilne kompleksy o średnicy około 1µm. Analogiczne zmiany zachodzą w układzie modelowym insulina – protamina. Modyfikowany dekstran, chitozan i hydroksypropyloceluloza nie oddziałują z insuliną tak jak protamina i PAH – ARG.Jako czynnik ułatwiający agregację insuliny w środowisku obojętnym zastosowano jony cynku. Udowodniono, że insulina w obecności ZnCl2 oddziałuje z każdym z badanych polimerów. W preparatach insuliny z modyfikowanym dekstranem, chitozanem i hydroksypropylocelulozą w obecności jonów cynku tworzą się duże stabilne kompleksy. Wykazano, że jony cynku dodatkowo stabilizują kompleksy insulina – PAH – ARG. Eksperymenty przeprowadzone in vivo potwierdziły skuteczność działania nowych układów insulinowych na bazie PAH – ARG, dodatkowo stabilizowanych jonami cynku.The aim of the following thesis was to offer an analysis of interactions between the insulin and a chosen cationically modified polymers: dextran, chitosan, hydroxypropyl cellulose and polyallylamine hydrochloride (PAH).The study treats about types of insulin preparations and allergic reactions to insulin due to additives included in the formulation, especially protamine.Several attempts have been made by a use of biocompatible cationically modified polymers to develop new safer long-acting insulin formulations. Similarly to protamine they characterize with a positive charge and as well can they affect the activity of other biopolymers by forming complexes. It has been shown that in systems composed of insulin PAH modified arginine (ARG) produce large, stable complexes with a diameter of about 1 micrometer. Similar changes occur in a model system of insulin - protamine. The modified dextran, chitosan and hydroxypropyl do not interact with insulin, such as protamine, or PAH – ARG. Zinc ions were used as a facilitator of insulin aggregation in a neutral environment. It has been proved that the insulin in the presence of ZnCl2 interacts with all of the tested polymers. The insulin formulations of modified dextran, chitosan and hydroxypropyl cellulose form large stable complexes in the presence of zinc ions. It has been shown that zinc ions also stabilize insulin complexes – PAH – ARG. A series of experiments conducted in vivo confirmed the effectiveness of the new system on the basis of insulin systems PAH – ARG, additionally stabilized by zinc ions

Modification of substandard EPDM with amorphous thermoplastic polyesters (PETG and PEF): microstructure and physical properties

The phase morphology, thermal behavior and mechanical properties of two series of polymer blends based on ethylene/propylene/diene rubber (EPDM) and amorphous homologues of poly(ethylene terephthalate), i.e. glycol modified poly(ethylene terephthalate) (PETG) and poly(ethylene furanoate) (PEF), were investigated. The morphology of the blends shows a two phase structure in which the minor phase (amorphous polyester) is dispersed as domains in the major (EPDM) continuous matrix phase. Differential calorimetry studies confirmed that both systems were immiscible and exhibits two glass transitions. The melting peak area of EPDM in the blends decreased as the amount of the other component increased. The values of stress at strain of 100% were improved upon the increasing content of PETG in EPDM system, while only slight decrease of this value was observed. Moreover, the strong improvement of hardness and thermo-oxidative stability along with an increasing content of amorphous polyester phase was reported

Wpływ warunków syntezy na masę cząsteczkową oraz właściwości mechaniczne i termiczne poli(2,5-furanianu heksametylenowego)

Poly(hexamethylene 2,5-furanate) (PHF) was obtained by melt polycondensation. The process was carried out at temperatures of 230, 235 and 240°C. It has been shown that the selection of the optimal parameters of the synthesis process leads to the obtaining of biomaterials of high molecular weight, and thus better mechanical and thermal properties. The relationship between the molecular weight and the mobility of polymer chains, and consequently the temperature of phase changes and mechanical properties, was determined.Poli(2,5-furanian heksametylenowy) (PHF) otrzymano metodą polikondensacji w stanie stopionym. Proces prowadzono w temperaturze 230, 235 i 240°C. Wykazano, że dobór optymalnych parametrów procesu syntezy prowadzi do otrzymania biomateriałów o dużej masie cząsteczkowej, a tym samym lepszych właściwościach mechanicznych i termicznych. Określono zależność między masą cząsteczkową a ruchliwością łańcuchów polimerowych, a w konsekwencji temperaturą przemian fazowych i właściwościami mechanicznymi

Functional Polymer Hybrid Nanocomposites Based on Polyolefins: A Review

For the last twenty years, polymer hybrid nanocomposites have enjoyed unflagging interest from numerous scientific groups and R&D departments, as they provide notable enhancement of properties, even at low nanofillers’ content. Their performance results from many factors, the most important of which is the uniform distribution in the entire volume of the matrix, that still is very challenging, but is the right choice of two types of nanoparticles that can lead to an increase of dispersion stability and even more uniform distribution of fillers. The incorporation of two types of nanofillers, especially when they differ in aspect ratio or chemical nature, allows to additively reduce the price of the final composite by replacing the more expensive filler with the cheaper one, or even synergistically improving the properties, e.g., mechanical, thermal, and barrier, etc., that can extend their usage in the industry. Despite numerous review papers on nanocomposites, there is no review on how the introduction of a hybrid system of nanofillers affects the properties of polyolefins, which are the most commonly used engineering plastics. This review deeply focuses on the structure–properties relationship of polyolefins-based hybrid nanocomposites, especially based on two types of polyethylenes (low-density polyethylenes (LDPE) and high-density polyethylenes (HDPE)) and polypropylene

Synthesis of Epoxy Methacrylate Resin and Coatings Preparation by Cationic and Radical Photocrosslinking

This work involves the synthesis of hybrid oligomers based on the epoxy methacrylate resin. The EA resin was obtained by the modification of industrial-grade bisphenol A-based epoxy resin and methacrylic acid has been synthesized in order to develop multifunctional resins comprising both epoxide group and reactive, terminal unsaturation. Owing to the presence of both epoxy and double carbon–carbon pendant groups, the reaction product exhibits photocrosslinking via two distinct mechanisms: (i) cationic ring-opening polymerization and (ii) free radical polymerization. Monitoring of EA synthesis reactions over time using PAVs, MAAC and NV parameters, and the FT-IR method reveals that esterification reactions proceed faster at the start, exhibiting over 40% of conversion within the initial 60 min, which can be associated with a relatively high concentration of reactive sites and low viscosity of the reaction mixture at the initial reaction stage. With the further increase in the reaction time, the reaction rate tends to decrease. The control of the EA synthesis process can guide how to adjust reactions to obtain EAs with desired characteristics. Based on obtained values, one can state that the optimum synthesis time of about 4–5 h should be adopted to prepare EAs having both epoxy groups and unsaturated double bonds. The structure of the obtained EA was confirmed by FT-IR and NMR methods, as well as the determination of partial acid value and epoxy equivalent. Samples at various stages of synthesis were cured with UV radiation in order to study the kinetics of the process according to cationic and radical polymerization determined via photo-differential scanning calorimetry (photo-DSC) and real-time infrared spectroscopy (RT-IR) and then the properties of the cured coatings were tested. It turned out that the cationic polymerization was slower with a lower conversion of the photoreactive groups, as compared to the radical polymerization. All the obtained EA coatings were characterized by good properties of cured coatings and can be successfully used in the coating-forming sector

The Properties of Poly(ester amide)s Based on Dimethyl 2,5-Furanedicarboxylate as a Function of Methylene Sequence Length in Polymer Backbone

A series of poly(ester amide)s based on dimethyl furan 2,5-dicarboxylate (DMFDC), 1,3-propanediol (PDO), 1,6-hexylene glycol (HDO), and 1,3-diaminopropane (DAP) were synthesized via two-step melt polycondensation. The phase transition temperatures and structure of the polymers were studied by differential scanning calorimetry (DSC). The positron annihilation lifetime spectroscopy (PALS) measurement was carried out to investigate the free volume. In addition, the mechanical properties of two series of poly(ester amide)s were analyzed. The increase in the number of methylene groups in the polymer backbone resulted in a decrease in the values of the transition temperatures. Depending on the number of methylene groups and the content of the poly(propylene furanamide) (PPAF), both semi-crystalline and amorphous copolymers were obtained. The free volume value increased with a greater number of methylene groups in the polymer backbone. Moreover, with a lower number of methylene groups, the value of the Young modulus and stress at break increased