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1.
J Chromatogr A ; 1714: 464557, 2024 Jan 11.
Article in English | MEDLINE | ID: mdl-38065028

ABSTRACT

As commodity plastics, polyolefins are in high demand and used in innumerable applications. An important reason for their success-story is their high versatility in terms of applications. The application range of polyolefins was significantly extended through the development of functionalization. A common functionalization for improving the compatibility of polyolefins with more polar polymers and surfaces is grafting with maleic anhydride. While maleic anhydride-grafted polyolefins have found widespread application, methods for their characterization remain rudimentary compared to the developments seen in the structural characterization of polyolefins in general. Herein, we propose two new approaches for determining the degree of functionalization as a function of the molar mass of maleic anhydride grafted polyolefins. On the one hand, the latest generation bandpass filter-based IR detectors are shown to be sensitive to the carbonyl moiety of MAH. After optimization of analysis conditions, the relation between MAH content and molar mass could be unraveled in an easily applicable approach suitable for routine analysis. On the other hand, the high reactivity of MAH was leveraged in a tagging approach. By imidization with a UV chromophore, MAH distribution can be assessed by HT-GPC-UV with significantly higher sensitivity compared to HT-GPC-IR.


Subject(s)
Maleic Anhydrides , Polyethylene , Polyethylene/chemistry , Maleic Anhydrides/chemistry , Polyenes , Polymers/chemistry
2.
ACS Appl Bio Mater ; 6(12): 5333-5348, 2023 Dec 18.
Article in English | MEDLINE | ID: mdl-38032020

ABSTRACT

The conformational changes of poly(maleic anhydride-alt-styrene) (PSMA) modified with different amino acids (PSMA-Aa) were studied in an aqueous medium as a function of ionic strength and pH. The specific viscosity of PSMA-Aa decreased with increasing salt concentration due to a more compact conformation. There was a decrease in surface tension with increasing concentrations of the modified polyelectrolyte having a greater effect for the PSMA modified with l-phenylalanine at pH 7.0, demonstrating a greater surface-active character. The conformational changes were also confirmed by molecular dynamics studies, indicating that PSMA-Aa exhibits a compact structure at pH 4.0 and a more extended structure at pH 7.0. On the other hand, the conformational changes of PSMA-Aa were related to its biological response, where the higher surface-active character of the PSMA modified with l-phenylalanine correlates very well with the higher hemolytic activity observed in red blood cells, in which the surface-active capacity supports lytic potency in erythrocytes. The cytocompatibility assays indicated that there were no significant cytotoxic effects of the PSMA-Aa. Additionally, in solvent-accessible surface area studies, it was shown that the carboxylate groups of the PSMA modified with l-phenylalanine are more exposed to the solvent at pH 7.0 and high salt concentrations, which correlates with lower fluorescence intensity, reflecting a loss of mitochondrial membrane potential. It is concluded that the study of the conformational changes in PE modified with amino acids is essential for their use as biomaterials and relevant to understanding the possible effects of PE modified with amino acids in biological systems.


Subject(s)
Amino Acids , Maleic Anhydrides , Humans , Maleic Anhydrides/chemistry , Polystyrenes/chemistry , Water , Phenylalanine , Hemolysis , Solvents
3.
Molecules ; 28(13)2023 Jun 26.
Article in English | MEDLINE | ID: mdl-37446656

ABSTRACT

Under tropospheric conditions, 2-butenedial is photochemically removed to produce secondary organic aerosol. Upon solar irradiation in the lower troposphere, the main photochemical products are ketene-enol (a key intermediate product), furanones, and maleic anhydride. The oxidative reaction mechanism was studied using the multireference method CASSCF to explore the hypersurface of the two most accessible singlet excited states, and by DFT for the ground state. Photoisomerization of 2-butenedial in the first excited state directly produces ground state ketene-enol upon nonradiative relaxation. From this intermediate, furan-2-ol and successively 3H-furan-2-one and 5H-furan-2-one are formed. The cooperative effect of two water molecules is essential to catalyze the cyclization of ketene-enol to furan-2-ol, followed by hydrogen transfers to furanones. Two water molecules are also necessary to form maleic anhydride from furan-2-ol. For this last reaction, in which one extra oxygen must be acquired, we hypothesize a mechanism with singlet oxygen as the oxidant.


Subject(s)
Maleic Anhydrides , Models, Theoretical , Maleic Anhydrides/chemistry , Isomerism , Furans/chemistry , Water/chemistry
4.
Bioresour Technol ; 380: 129125, 2023 Jul.
Article in English | MEDLINE | ID: mdl-37127171

ABSTRACT

The purpose of this paper was to explore the promotion of maleic anhydride on the polymerization of precursors into humus in composting, and analyze the changes of key functional enzymes. The results showed that the content of humus in the treatment group added maleic anhydride (MAH) was higher than that in the control check (CK). The decrease rate of humus precursor concentration of MAH was also higher than that of CK. In MAH, the activities of laccase and tyrosinase were improved, thus enhanced the catalytic conversion of humus precursors. The analysis of bacterial community showed that maleic anhydride optimized the community structure of humification functional enzymes producing bacteria, with the most obvious increase of Firmicutes. In conclusion, this study provided theoretical supports for the introduction of maleic anhydride into the compost system to promote the polymerization of precursors to form humus.


Subject(s)
Composting , Soil , Maleic Anhydrides/chemistry , Bacteria , Polymerization , Manure
5.
J Biomater Appl ; 37(7): 1286-1299, 2023 02.
Article in English | MEDLINE | ID: mdl-36537783

ABSTRACT

Implantation of bone substitutes is the treatment of choice for bone defects exceeding a critical size, when self-healing becomes impossible. The use of 3D printing techniques allows the construction of scaffolds with customized properties. However, there is a lack of suitable materials for bone replacement. In this study, maleic anhydride-grafted poly (lactic acid) (MAPLA) was investigated as a potential compatibilizer agent for 3D-printed polylactic acid (PLA)/hydroxyapatite (HA) composites, in order to enhance the physicochemical and biological properties of the scaffolds. The grafting process was performed by reactive processing in a torque rheometer, with the evaluation of the use of different concentrations of maleic anhydride (MA). The success of the grafting reaction was confirmed by titration of acid groups and spectroscopic analyses, indicating the presence of succinic anhydride groups on the PLA chain. Morphological analysis of the PLA/HA 3D scaffolds, using SEM, revealed that the use of the compatibilizer resulted in a structure free from voids and holes. The compatibilization also increased the degradation process. On the other hand, TGA and DSC analyses revealed that the use of a compatibilizer had little effect on the thermal properties of the composite. Most importantly, the samples with compatibilizer were demonstrated to have a minimal cytotoxic effect on human mesenchymal stem cells (MSCs), promoting the osteogenic differentiation of these cells in a medium without the addition of classical osteogenic factors. Therefore, the grafting of PLA/HA composites improved their physicochemical and biological properties, especially the induction of MSC osteogenic differentiation, demonstrating the potential of these scaffolds for bone tissue replacement.


Subject(s)
Mesenchymal Stem Cells , Osteogenesis , Humans , Durapatite/chemistry , Maleic Anhydrides/chemistry , Tissue Engineering/methods , Polyesters/chemistry , Cell Differentiation , Tissue Scaffolds/chemistry
6.
Molecules ; 27(23)2022 Nov 23.
Article in English | MEDLINE | ID: mdl-36500234

ABSTRACT

Vegetable oils are bio-based and sustainable starting materials that can be used to develop chemicals for industrial processes. In this study, the functionalization of three vegetable oils (grape, hemp, and linseed) with maleic anhydride was carried out either by conventional heating or microwave activation to obtain products that, after further reactions, can enhance the water dispersion of oils for industrial applications. To identify the most abundant derivatives formed, trans-3-octene, methyl oleate, and ethyl linoleate were reacted as reference systems. A detailed NMR study, supported by computational evidence, allowed for the identification of the species formed in the reaction of trans-3-octene with maleic anhydride. The signals in the 1H NMR spectra of the alkenyl succinic anhydride (ASA) moieties bound to the organic chains were clearly identified. The reactions achieved by conventional heating were carried out for 5 h at 200 °C, resulting in similar or lower amounts of ASA units/g of oil with respect to the reactions performed by microwave activation, which, however, induced a higher viscosity of the samples.


Subject(s)
Maleic Anhydrides , Plant Oils , Maleic Anhydrides/chemistry , Plant Oils/chemistry , Magnetic Resonance Spectroscopy , Chemical Phenomena , Magnetic Resonance Imaging
7.
Nat Commun ; 13(1): 7595, 2022 Dec 09.
Article in English | MEDLINE | ID: mdl-36494357

ABSTRACT

Closed-loop chemical recycling provides a solution to the end-of-use problem of synthetic polymers. However, it remains a major challenge to design dynamic bonds, capable of effective bonding and reversible cleaving, for preparing chemically recyclable cross-linked polymers. Herein, we report a dynamic maleic acid tertiary amide bond based upon reversible amidation reaction between maleic anhydrides and secondary amines. This dynamic bond allows for the construction of polymer networks with tailorable and robust mechanical properties, covering strong elastomers with a tensile strength of 22.3 MPa and rigid plastics with a yield strength of 38.3 MPa. Impressively, these robust polymeric materials can be completely depolymerized in an acidic aqueous solution at ambient temperature, leading to efficient monomer recovery with >94% separation yields. Meanwhile, the recovered monomers can be used to remanufacture cross-linked polymeric materials without losing their original mechanical performance. This work unveils a general approach to design polymer networks with tunable mechanical performance and closed-loop recyclability, which will open a new avenue for sustainable polymeric materials.


Subject(s)
Maleic Anhydrides , Polymers , Polymers/chemistry , Maleic Anhydrides/chemistry , Recycling , Tensile Strength , Plastics
8.
Int J Mol Sci ; 23(13)2022 Jun 28.
Article in English | MEDLINE | ID: mdl-35806171

ABSTRACT

Poly(butylene sebacate-co-terephthalate) (PBSeT) is a biodegradable flexible polymer suitable for melt blending with other biodegradable polymers. Melt blending with a compatibilizer is a common strategy for increasing miscibility between polymers. In this study, PBSeT polyester was synthesized, and poly(lactic acid) (PLA) was blended with 25 wt% PBSeT by melt processing with 3-6 phr PLA-grafted maleic anhydride (PLA-g-MAH) compatibilizers. PLA-g-MAH enhanced the interfacial adhesion of the PLA/PBSeT blend, and their mechanical and morphological properties confirmed that the miscibility also increased. Adding more than 6 phr of PLA-g-MAH significantly improved the mechanical properties and accelerated the cold crystallization of the PLA/PBSeT blends. Furthermore, the thermal stabilities of the blends with PLA-g-MAH were slightly enhanced. PLA/PBSeT blends with and without PLA-g-MAH were not significantly different after 120 h, whereas all blends showed a more facilitated hydrolytic degradation rate than neat PLA. These findings indicate that PLA-g-MAH effectively improves PLA/PBSeT compatibility and can be applied in the packaging industry.


Subject(s)
Maleic Anhydrides , Polyesters , Maleic Anhydrides/chemistry , Polyesters/chemistry , Polymers/chemistry
9.
J Am Chem Soc ; 144(33): 15286-15294, 2022 08 24.
Article in English | MEDLINE | ID: mdl-35796412

ABSTRACT

Single-molecule white-light emission (SMWLE) has many advantages in practical applications; however, the fabrication of SMWLE from nonconjugated luminescent polymers, namely, clusteroluminogens (CLgens), is still a big challenge. Herein, the first example of linear nonconjugated polyesters with SMWLE is reported. Twenty-four kinds of nonconjugated aliphatic polyesters with tunable clusteroluminescence (CL) colors and efficiency were synthesized by the copolymerization of six epoxides and four anhydrides. Experimental and calculation results prove that, at the primary structure level, the balance of structural flexibility and rigidity via adjusting the side-chain length significantly enhances the efficiency of CL without wavelength change. However, altering the chemical structures of the monomer from succinic anhydride to trans-maleic anhydride (MA), cis-MA, and citraconic anhydride (CA), secondary structures of these polyesters change from helix to straight and folding sheet accompanied by gradually red-shifted CL from 460 to 570 nm due to the increase in through-space n-π* interactions, as demonstrated by the computational and experimental results. Then, pure SMWLE with CIE coordination (0.30, 0.32) based on overlapped short-wavelength and long-wavelength CL is achieved in CA-based polyesters. This work not only provides further insights into the emission mechanism of CL but also provides a new strategy to manipulate the properties of CL by regulating the hierarchical structures of CLgens.


Subject(s)
Maleic Anhydrides , Polyesters , Anhydrides/chemistry , Maleic Anhydrides/chemistry , Polyesters/chemistry , Polymerization , Polymers/chemistry
10.
Int J Biol Macromol ; 201: 364-377, 2022 Mar 15.
Article in English | MEDLINE | ID: mdl-34998880

ABSTRACT

Agar is modified by chemical methods to improve its functional properties and meet the increasing demand of the market. Some of the functional properties of agar are improved after chemical modification, while other properties are reduced, especially gel strength. This study aimed to comprehensively improve the functional properties of agar through acylation and crosslinking by reacting with maleic anhydride. 13C NMR indicated the maleylation reaction was preferred at the C2 hydroxyl group of D-galactose, and the crosslinking reactions occurred at the C2 and C6 hydroxyl groups of D-galactose in different agar chains. Interestingly, the maleylated agar monoester had higher gel transparency (1.5%, w/v) of up to 76% than the native agar (58%). However, it showed a significant decrease in gel strength from 783 g/cm2 to 403 g/cm2, while crosslinking endowed agar with higher gel strength (845 g/cm2) and gel transparency (78.4%). The high transparency of the modified agar plate made colony observation and colony counting easy. Maleylation of agar further enhanced the freeze-thaw stability of agar gel (24.8%, 7th freeze-thaw cycles). Overall, the maleylated agar possessed superior functional properties, and it could be used as food, bacteriological, and biotechnological agar.


Subject(s)
Galactose , Maleic Anhydrides , Acylation , Agar/chemistry , Chemical Phenomena , Maleic Anhydrides/chemistry
11.
Molecules ; 26(19)2021 Sep 30.
Article in English | MEDLINE | ID: mdl-34641470

ABSTRACT

Framing the Circular Bioeconomy, the use of reactive compatibilizers was applied in order to increase the interfacial adhesion and, hence, the physical properties and applications of green composites based on biopolymers and food waste derived lignocellulosic fillers. In this study, poly(butylene succinate) grafted with maleic anhydride (PBS-g-MAH) was successfully synthetized by a reactive melt-mixing process using poly(butylene succinate) (PBS) and maleic anhydride (MAH) that was induced with dicumyl peroxide (DCP) as a radical initiator and based on the formation of macroradicals derived from the hydrogen abstraction of the biopolymer backbone. Then, PBS-g-MAH was used as reactive compatibilizer for PBS filled with different contents of pistachio shell flour (PSF) during melt extrusion. As confirmed by Fourier transform infrared (FTIR), PBS-g-MAH acted as a bridge between the two composite phases since it was readily soluble in PBS and could successfully form new esters by reaction of its multiple MAH groups with the hydroxyl (-OH) groups present in cellulose or lignin of PSF and the end ones in PBS. The resultant compatibilized green composites were, thereafter, shaped by injection molding into 4-mm thick pieces with a wood-like color. Results showed significant increases in the mechanical and thermomechanical rigidity and hardness, meanwhile variations on the thermal stability were negligible. The enhancement observed was related to the good dispersion and the improved filler-matrix interfacial interactions achieved by PBS-g-MAH and also to the PSF nucleating effect that increased the PBS's crystallinity. Furthermore, water uptake of the pieces progressively increased as a function of the filler content, whereas the disintegration in controlled compost soil was limited due to their large thickness.


Subject(s)
Biocompatible Materials/chemistry , Butylene Glycols/chemistry , Flour/analysis , Maleic Anhydrides/chemistry , Peroxides/chemistry , Pistacia/chemistry , Polymers/chemistry , Temperature , Tensile Strength
12.
Mar Drugs ; 19(9)2021 Aug 26.
Article in English | MEDLINE | ID: mdl-34564148

ABSTRACT

In this work, the physicochemical properties of maleic anhydride (MAH)-modified κ-carrageenan (κCar) (MC) were characterized and compared with those of native κ-carrageenan (NC). The Fourier transform infrared spectrum of MC exhibited that κCar was successfully modified. Thermogravimetric analysis indicated that the thermal stability of MC was decreased. When the degree of substitution was 0.032, MC exhibited a low gel strength (759 g/cm2), gelling temperature (33.3 °C), and dehydration rate (60.3%). Given the excellent film-forming ability of κCar, MC films were then prepared and were found to have better mechanical and barrier properties (UV and water) than NC films. With regard to optical properties, MC films could completely absorb UV light in the range of 200-236 nm. The water contact angle of MC films was higher than that of NC films. Moreover, the elongation at break increased from 26.9% to 163%. These physicochemical property changes imply that MC can be employed in polysaccharide-based films.


Subject(s)
Carrageenan/chemistry , Maleic Anhydrides/chemistry , Temperature , Tensile Strength , Ultraviolet Rays , Water/chemistry
13.
Int J Mol Sci ; 22(17)2021 Sep 04.
Article in English | MEDLINE | ID: mdl-34502514

ABSTRACT

In this study, we employed the copolymer poly(methyl vinyl ether-alt-maleic monoethyl ester) (PMVEMA-Es) and three fluorene-based cationic conjugated polyelectrolytes to develop fluorescent nanoparticles with emission in the blue, green and red spectral regions. The size, Zeta Potential, polydispersity, morphology, time-stability and fluorescent properties of these nanoparticles were characterized, as well as the nature of the interaction between both PMVEMA-Es and fluorescent polyelectrolytes. Because PMVEMA-Es contains a carboxylic acid group in its structure, the effects of pH and ionic strength on the nanoparticles were also evaluated, finding that the size is responsive to pH and ionic strength, largely swelling at physiological pH and returning to their initial size at acidic pHs. Thus, the developed fluorescent nanoparticles can be categorized as pH-sensitive fluorescent nanogels, since they possess the properties of both pH-responsive hydrogels and nanoparticulate systems. Doxorubicin (DOX) was used as a model drug to show the capacity of the blue-emitting nanogels to hold drugs in acidic media and release them at physiological pH, from changes in the fluorescence properties of both nanoparticles and DOX. In addition, preliminary studies by super-resolution confocal microscopy were performed, regarding their potential use as image probes.


Subject(s)
Drug Carriers/chemical synthesis , Fluorenes/chemistry , Maleic Anhydrides/chemistry , Polyvinyls/chemistry , Antibiotics, Antineoplastic/pharmacology , Color , Doxorubicin/pharmacology , Drug Carriers/chemistry , Esters/chemistry , Fluorescence Resonance Energy Transfer/methods , Humans , Hydrogen-Ion Concentration , Methyl Ethers/chemistry , Nanogels/chemistry , Nanoparticles/chemistry , Particle Size , Polymers/chemistry , Vinyl Compounds/chemistry
14.
Carbohydr Polym ; 270: 118359, 2021 Oct 15.
Article in English | MEDLINE | ID: mdl-34364604

ABSTRACT

Today's widely used and rapidly updated electronic substrates are composed of petroleum-based polymers, but the resulting electronic waste (such as Dioxin, oxole, PCBs, etc.) will cause massive harm to the environment and human body. Therefore, we report an effective approach for fabricating recyclable and high-performance cellulose films as green electronic substrates by calendering. The crosslinking between CH and CHCH in cellulose modified by maleic anhydride led to the in-situ formation of a chemical crosslinking network, and hydrogen bonds acted as a sacrificial physical crosslinking network. The dual crosslinked cellulose film exhibits high strength (120.56 MPa), improved elongation (increased by 263%), and outstanding thermal stability (thermal decomposition temperature is 311 °C). Further, the film has been successfully used as a substrate for biomass sensor and realized apparent responses to changes. The scientific strategy paves the way for the large-scale fabrication of high-performance cellulose films and simultaneously promotes green electronic substrates' industrialization.


Subject(s)
Cellulose/chemistry , Electronics , Maleic Anhydrides/chemistry , Biosensing Techniques , Green Chemistry Technology/methods , Humans , Hydrogen Bonding , Microscopy, Electrochemical, Scanning/methods , Polymers/chemistry , Temperature , Tensile Strength , X-Ray Diffraction/methods
15.
Carbohydr Polym ; 269: 118268, 2021 Oct 01.
Article in English | MEDLINE | ID: mdl-34294300

ABSTRACT

Major obstacles in the development of nanoformulations as efficient drug delivery systems are the rapid clearance from blood circulation and lysosomal entrapment. To overcome these problems, a polysaccharide-based core-shell type charge-switchable nanoformulation (CS-LA-DMMA/CMCS/PAMAM@DOX) is constructed to improve antitumor efficacy of DOX. By applying carboxymethyl chitosan (CMCS) as bridge polymer and negatively charged chitosan-derivative as outer shell, the stability and pH-sensitivity of this nanoformulation is promisingly enhanced. Furthermore, the positively charged PAMAM@DOX could escape from lysosomes via "proton sponge effect" and "cationic-anionic interaction with lysosome membranes". Admirable cellular uptake and high apoptosis/necrosis rate were detected in this study. In vitro assays demonstrate that the CS-LA-DMMA/CMCS/PAMAM@DOX was internalized into HepG2 cells predominantly via the clathrin-mediated endocytosis pathway. Excitingly, in vivo studies showed that high accumulation of CS-LA-DMMA/CMCS/PAMAM@DOX in tumor tissue led to enhanced tumor inhibition. Compared with free DOX, the tumor inhibition rate of nanoformulation was improved up to 226%.


Subject(s)
Antineoplastic Agents/therapeutic use , Chitosan/analogs & derivatives , Doxorubicin/therapeutic use , Drug Carriers/chemistry , Neoplasms/drug therapy , Animals , Antineoplastic Agents/chemistry , Apoptosis/drug effects , Carbohydrate Sequence , Chitosan/chemical synthesis , Chitosan/chemistry , Chitosan/metabolism , Dendrimers/chemical synthesis , Dendrimers/chemistry , Dendrimers/metabolism , Doxorubicin/chemistry , Drug Carriers/metabolism , Drug Liberation , Endocytosis/physiology , Hep G2 Cells , Humans , Hydrogen-Ion Concentration , Lysosomes/metabolism , Male , Maleic Anhydrides/chemistry , Maleic Anhydrides/metabolism , Mice, Inbred BALB C , Necrosis/chemically induced , Neoplasms/diagnostic imaging , Polyamines/chemical synthesis , Polyamines/chemistry , Polyamines/metabolism , Xenograft Model Antitumor Assays
16.
Molecules ; 26(4)2021 Feb 17.
Article in English | MEDLINE | ID: mdl-33671148

ABSTRACT

NaYF4:Er,Yb upconversion luminescent nanoparticles (UCNPs) were prepared by hydrothermal methods at 180 °C for 24 h. The X-ray diffraction (XRD) and TEM (transmission electron microscopy) images show that the resulting 60 nm UCNPs possess a hexagonal structure. In this work, maleic anhydride (MA) was grafted on the surface of UCNPs to induce hydrophilic properties. The photoluminescence spectra (PL) show upconversion emissions centered around 545 nm and 660 nm under excitation at 980 nm. The luminescent inks, including UCNPs@MA, polyvinyl alcohol (PVA), deionized water (DI), and ethylene glycol (EG), exhibit suitable properties for screen printing, such as high stability, emission intensity, and tunable dynamic viscosity. The printed patterns with a height of 5 mm and a width of 1.5 mm were clearly observed under the irradiation of a 980 nm laser. Our strategy provides a new route for the controlled synthesis of hydrophilic UCNPs, and shows that the UCNPs@MAs have great potential in applications of anti-counterfeiting packing.


Subject(s)
Fluorides/chemistry , Green Chemistry Technology , Ink , Luminescence , Maleic Anhydrides/chemistry , Nanoparticles/chemistry , Spectrum Analysis , Ytterbium/chemistry , Yttrium/chemistry , Erbium/chemistry , Optical Phenomena , Polymers/chemistry , Spectroscopy, Fourier Transform Infrared , Vibration , X-Ray Diffraction
17.
Molecules ; 26(1)2021 Jan 05.
Article in English | MEDLINE | ID: mdl-33466389

ABSTRACT

This research work reports the potential of maleinized linseed oil (MLO) as biobased compatibilizer in polylactide (PLA) and a thermoplastic elastomer, namely, polystyrene-b-(ethylene-ran-butylene)-b-styrene (SEBS) blends (PLA/SEBS), with improved impact strength for the packaging industry. The effects of MLO are compared with a conventional polystyrene-b-poly(ethylene-ran-butylene)-b-polystyrene-graft-maleic anhydride terpolymer (SEBS-g-MA) since it is widely used in these blends. Uncompatibilized and compatibilized PLA/SEBS blends can be manufactured by extrusion and then shaped into standard samples for further characterization by mechanical, thermal, morphological, dynamical-mechanical, wetting and colour standard tests. The obtained results indicate that the uncompatibilized PLA/SEBS blend containing 20 wt.% SEBS gives improved toughness (4.8 kJ/m2) compared to neat PLA (1.3 kJ/m2). Nevertheless, the same blend compatibilized with MLO leads to an increase in impact strength up to 6.1 kJ/m2, thus giving evidence of the potential of MLO to compete with other petroleum-derived compatibilizers to obtain tough PLA formulations. MLO also provides increased ductile properties, since neat PLA is a brittle polymer with an elongation at break of 7.4%, while its blend with 20 wt.% SEBS and MLO as compatibilizer offers an elongation at break of 50.2%, much higher than that provided by typical SEBS-g-MA compatibilizer (10.1%). MLO provides a slight decrease (about 3 °C lower) in the glass transition temperature (Tg) of the PLA-rich phase, thus showing some plasticization effects. Although MLO addition leads to some yellowing due to its intrinsic yellow colour, this can contribute to serving as a UV light barrier with interesting applications in the packaging industry. Therefore, MLO represents a cost-effective and sustainable solution to the use of conventional petroleum-derived compatibilizers.


Subject(s)
Biocompatible Materials/chemistry , Elastomers/chemistry , Linseed Oil/chemistry , Maleic Anhydrides/chemistry , Polyesters/chemistry , Polymers/chemistry , Product Packaging/methods , Temperature , Tensile Strength
18.
Bioorg Chem ; 106: 104465, 2021 01.
Article in English | MEDLINE | ID: mdl-33229119

ABSTRACT

A new series of pyrrole analogs were developed via the microwave irradiation synthesis. Consequently, got a high yield of the products. As pyrroles are familiar for showing various biological properties, all obtained compounds were screened for their antioxidant properties, most of the compounds showing significant activity. In fact, the motifs 5e, 5g, 5h and 5m showed outstanding antioxidant properties. Further, to enlighten the biologically energetic behavior underlying the antioxidant activity, compounds DFT studies were performed. Noteworthy results have been attained and the structure activity relationship (SAR) was discussed with the support of this results. It was found that highly biological active compounds exhibited a low HOMO-LUMO energy gap (Eg) and the high Eg value compounds show very low/negligible or inactive antioxidant activities. In other cases, compounds containing high HOMO energy levels also provide high antioxidant activity. The thought-provoking point of our results is that theoretical descriptors of the HOMO-LUMO energy gap and the highest occupied molecular orbital energy are important descriptors in the bioorganic research to support the biological experiments.


Subject(s)
Free Radical Scavengers/chemistry , Maleimides/chemistry , Density Functional Theory , Free Radical Scavengers/chemical synthesis , Free Radical Scavengers/radiation effects , Maleic Anhydrides/chemistry , Maleic Anhydrides/radiation effects , Maleimides/chemical synthesis , Maleimides/radiation effects , Microwaves , Models, Chemical , Molecular Structure , Phenylenediamines/chemistry , Phenylenediamines/radiation effects , Structure-Activity Relationship
19.
Int J Biol Macromol ; 166: 876-883, 2021 Jan 01.
Article in English | MEDLINE | ID: mdl-33144251

ABSTRACT

Enzyme immobilization has been known to be one of the methods to improve the stability and reusability of enzyme. In this study, a strategy to optimize laccase immobilization on polyethylene terephthalate grafted with maleic anhydride electrospun nanofiber mat (PET-g-MAH ENM) was developed. The development involves the screening and optimization processes of the crucial factors that influence the immobilization yield such as enzyme concentration, pH values, covalent bonding (CV) time, CV temperature, crosslinking (CL) time, CL temperature and glutaraldehyde concentration using two-level factorial design and Box-Behnken design (BBD), respectively. It was found that laccase concentration, pH values and glutaraldehyde concentration play important role in enhancing the immobilization yield of laccase on PET-g-MAH ENM in the screening process. Subsequently, the optimization result showed at 0.28 mg/ml laccase concentration, pH 3 and 0.45% (v/v) glutaraldehyde concentrations gave the highest immobilization yield at 87.64% which was 81.2% increment from the immobilization yield before optimization. Under the optimum condition, the immobilized laccase was able to oxidize 2, 2-azino-bis 3-ethylbenzothiazoline-6- sulfonic acid (ABTS) in a broad range of pH (pH 3-6) and temperature (20- 70 °C). Meanwhile, the kinetic parameters for Km and Vmax were 1.331 mM and 0.041 mM/min, respectively. It was concluded that the optimization of immobilized laccase on PET-g-MAH ENM enhance the performance of this biocatalyst.


Subject(s)
Enzymes, Immobilized/chemistry , Laccase/chemistry , Nanofibers/chemistry , Polyethylene Terephthalates/chemistry , Benzothiazoles/chemistry , Cross-Linking Reagents/chemistry , Enzymes, Immobilized/metabolism , Hydrogen-Ion Concentration , Kinetics , Laccase/metabolism , Maleic Anhydrides/chemistry , Sulfonic Acids/chemistry , Temperature
20.
Molecules ; 25(19)2020 Sep 30.
Article in English | MEDLINE | ID: mdl-33008017

ABSTRACT

Incorporation of nanocellulose could improve wear resistance of ultra-high molecular weight polyethylene (UHMWPE) for an artificial joint application. Yet, the extremely high melt viscosity of the polymer may constrict the mixing, leading to fillers agglomeration and poor mechanical properties. This study optimized the processing condition of UHMWPE/cellulose nanofiber (CNF) bionanocomposite fabrication in triple screw kneading extruder by using response surface methodology (RSM). The effect of the process parameters-temperature (150-190 °C), rotational speed (30-60 rpm), and mixing time (30-45 min)-on mechanical properties of the bionanocomposites was investigated. Homogenous filler distribution, as confirmed by scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) analysis, was obtained through the optimal processing condition of 150 °C, 60 rpm, and 45 min. The UHMWPE/CNF bionanocomposites exhibited improved mechanical properties in terms of Young's and flexural modulus by 11% and 19%, respectively, as compared to neat UHMWPE. An insignificant effect was observed when maleic anhydride-grafted-polyethylene (MAPE) was added as compatibilizer. The obtained results proved that homogenous compounding of high melt viscosity UHMWPE with CNF was feasible by optimizing the melt blending processing condition in triple screw kneading extruder, which resulted in improved stiffness, a contributing factor for wear resistance.


Subject(s)
Cellulose/chemistry , Nanocomposites/chemistry , Nanofibers/chemistry , Polyethylenes/chemistry , Analysis of Variance , Elastic Modulus , Maleic Anhydrides/chemistry , Nanocomposites/ultrastructure , Nanofibers/ultrastructure , Polyethylene/chemistry , Temperature , Tensile Strength
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