Synthesis of Lactic Acid-Based Thermosetting Resins and Their Ageing and Biodegradability

The present work is focused on the synthesis of bio-based thermoset polymers and their thermo–oxidative ageing and biodegradability. Toward this aim, bio-based thermoset resins with different chemical architectures were synthesized from lactic acid by direct condensation with ethylene glycol, glycerol and pentaerythritol. The resulting branched molecules with chain lengths (n) of three were then end-functionalized with methacrylic anhydride. The chemical structures of the synthesized lactic acid derivatives were confirmed by proton nuclear magnetic resonance spectroscopy (1H-NMR) and Fourier transform infrared spectroscopy (FT–IR) before curing. To evaluate the effects of structure on their properties, the samples were investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and the tensile testing. The samples went through thermo-oxidative ageing and biodegradation; and their effects were investigated. FT-IR and 1H-NMR results showed that three different bio-based resins were synthesized using polycondensation and end-functionalization. Lactic acid derivatives showed great potential to be used as matrixes in polymer composites. The glass transition temperature of the cured resins ranged between 44 and 52 °C. Pentaerythritol/lactic acid cured resin had the highest tensile modulus and it was the most thermally stable among all three resins. Degradative processes during ageing of the samples lead to the changes in chemical structures and the variations in Young’s modulus. Microscopic images showed the macro-scale surface degradation on a soil burial test.

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ISOLATION OF 2-CHLOROBENZIMIDAZOLE FROM MELIA DUBIA LEAF EXTRACT AND ITS STRUCTURAL CHARACTERISATION

International Journal of Pharmacy and Pharmaceutical Sciences ◽

10.22159/ijpps.2017v9i10.20573 ◽

2017 ◽

Vol 9 (10) ◽

pp. 67 ◽

Cited By ~ 2

Author(s):

G. Dayana Jeyaleela ◽

S. Irudaya Monisha ◽

J. Rosaline Vimala ◽

A. Anitha Immaculate

Keyword(s):

Mass Spectrometry ◽

1H Nmr ◽

Research Work ◽

Proton Nuclear Magnetic Resonance ◽

Resonance Spectroscopy ◽

Ft Ir ◽

Uv Visible ◽

Isolated Compound ◽

Promising Source

Objective: Natural products from medicinal plants, either as isolated compounds or as standardized plant extracts exhibit promising source of medicinal activity against various diseases. The aim of the present work was to make an attempt of isolation of bioactive principle and characterization of the isolated compound, from the medicinal plant Melia dubaiMethods: The extraction was done by a cold percolation method and the compound was separated and isolated by chromatography technique such as a thin layer chromatography (TLC), column chromatography and high-performance liquid chromatography (HPLC). The isolated compound was crystallized and the structural characterization of the isolated compound was made using UV-Visible, FT-IR, 1H-NMR, GC-MS and MS techniques which confirmed the structure of the isolated compound.Results: The separated and isolated compound was characterized by both physical and spectral methods like Ultraviolet-Visible spectroscopy (UV-Visible), Fourier transform infrared spectroscopy (FT-IR), Proton Nuclear Magnetic Resonance Spectroscopy (1H-NMR), Gas chromatography-mass spectrometry (GC-MS), and Mass spectrometry(MS). Based on the studies, organizational characteristics of one bioactive principle were deciphered. The results revealed that the isolated species is 2-chlorobenzimidazole and it agreed well with the reported value and spectra for 2-chlorobenzimidazole.Conclusion: The above results obtained in this research work clearly indicated the promising occurrence of 2-chlorobenzimidazole in Media dubia plant leaves. The future scope of these studies may guide us to view the biological activity of the isolated compound.

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Chemical composition, optical properties, and oxidative potential of water- and methanol-soluble organic compounds emitted from the combustion of biomass materials and coal

10.5194/acp-2021-159 ◽

2021 ◽

Author(s):

Tao Cao ◽

Meiju Li ◽

Chunlin Zou ◽

Xingjun Fan ◽

Jianzhong Song ◽

...

Keyword(s):

Optical Properties ◽

Organic Compounds ◽

1H Nmr ◽

Water Soluble ◽

Proton Nuclear Magnetic Resonance ◽

Resonance Spectroscopy ◽

Oxidative Potential ◽

Strong Light ◽

Chemical Structures ◽

Biomass Materials

Abstract. Biomass burning (BB) and coal combustion (CC) are important sources of brown carbon (BrC) in ambient aerosols. In this study, six biomass materials and five types of coal were combusted to generate fine smoke particles. The BrC fractions, including water-soluble organic compounds (WSOC), humic-like substances (HULIS), and methanol-soluble organic compounds (MSOC), were subsequently fractionated and their optical properties and chemical structures were then comprehensively investigated using UV-visible spectroscopy, proton nuclear magnetic resonance spectroscopy (1H-NMR), and fluorescence extraction-emission matrix spectroscopy (EEM) combined with parallel factor analysis (PARAFAC). In addition, the oxidative potential (OP) of BB and CC BrC was measured with the dithiothreitol (DTT) method. The results showed that WSOC, HULIS, and MSOC accounted for 2.3 %–22 %, 0.5 %–10 %, and 6.4 %–73 % of the total mass of combustion-derived PM2.5, respectively, with MSOC extracting the highest concentrations of organic compounds. The MSOC fractions had the highest light absorption capacity (mass absorption efficiency at 365 nm (MAE365): 1.0–2.7 m2/gC) for both BB and CC smoke, indicating that MSOC contained more of the strong light-absorbing components. Therefore, MSOC may better represent the total BrC than the water-soluble fractions. Some significant differences were observed between the BrC fractions emitted from BB and CC, with more water-soluble BrC fractions with higher MAE365 and lower absorption Ångström exponent values detected in smoke emitted from BB than from CC. The EEM-PARAFAC analysis identified four fluorophores: two protein-like, one humic-like, and one polyphenol-like. The protein-like substance was the dominant component of WSOC (47 %–80 %), HULIS (44 %–87 %), and MSOC (42 %–70 %). The 1H-NMR results suggested that BB BrC contained more oxygenated aliphatic functional groups (H-C-O), whereas CC BrC contained more unsaturated fractions (H-C-C = and Ar-H). The DTT assays indicated that BB BrC generally had a stronger OP (DTTmass, 2.6–85 pmol/min/μg) than CC BrC (DTTmass, 0.4–11 pmol/min/μg), with MSOC having a stronger OP than WSOC and HULIS. Therefore, the BrC fractions from BB had higher OP values than those from CC.

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Synthesis of Eugenol-Based Silicon-Containing Benzoxazines and Their Applications as Bio-Based Organic Coatings

Coatings ◽

10.3390/coatings8030088 ◽

2018 ◽

Vol 8 (3) ◽

pp. 88 ◽

Cited By ~ 19

Author(s):

Jinyue Dai ◽

Shimin Yang ◽

Na Teng ◽

Yuan Liu ◽

Xiaoqing Liu ◽

...

Keyword(s):

Thermal Stability ◽

Moisture Absorption ◽

High Hardness ◽

Resonance Spectroscopy ◽

Scanning Calorimetry ◽

Good Thermal Stability ◽

Chemical Structures ◽

Ring Opening Reaction ◽

Ft Ir ◽

Excellent Adhesion

In this work, several bio-based main-chain type benzoxazine oligomers (MCBO) were synthesized from eugenol derivatives via polycondensation reaction with paraformaldehyde and different diamine. Afterwards, their chemical structures were confirmed by Fourier Transform Infrared Spectroscopy (FT-IR) and Nuclear Magnetic Resonance Spectroscopy (1H-NMR). The curing reaction was monitored by Differential Scanning Calorimetry (DSC) and FT-IR. The polybenzoxazine films were prepared via thermal ring-opening reaction of benzoxazine groups without solvent, and their thermodynamic properties, thermal stability, and coating properties were investigated in detail. Results indicated that the cured films exhibited good thermal stability and mechanical properties, showing 10% thermal weight loss (Td10%) temperature as high as 408 °C and modulus at a room temperature of 2100 MPa as well as the glass transition temperature of 123 °C. In addition, the related coatings exhibited high hardness, excellent adhesion, good flexibility, low moisture absorption, and outstanding solvent resistance.

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Nepafenac-Loaded Cyclodextrin/Polymer Nanoaggregates: A New Approach to Eye Drop Formulation

Materials ◽

10.3390/ma12020229 ◽

2019 ◽

Vol 12 (2) ◽

pp. 229 ◽

Cited By ~ 5

Author(s):

Blanca Lorenzo-Veiga ◽

Hakon Sigurdsson ◽

Thorsteinn Loftsson

Keyword(s):

1H Nmr ◽

Self Assembly ◽

Topical Administration ◽

Water Soluble ◽

Resonance Spectroscopy ◽

Scanning Calorimetry ◽

Nmr Studies ◽

Water Soluble Polymers ◽

1H Nuclear Magnetic Resonance ◽

Ft Ir

The topical administration route is commonly used for targeting therapeutics to the eye; however, improving the bioavailability of drugs applied directly to the eye remains a challenge. Different strategies have been studied to address this challenge. One of them is the use of aggregates that are formed easily by self-assembly of cyclodextrin (CD)/drug complexes in aqueous solution. The aim of this study was to design a new eye drop formulation based on aggregates formed between CD/drug complexes. For this purpose, the physicochemical properties of the aggregates associated with six CDs and selected water-soluble polymers were analysed. Complex formation was studied using differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FT-IR) and 1H nuclear magnetic resonance spectroscopy (1H-NMR). Results showed that HPβCD performed best in terms of solubilization, while γCD performed best in terms of enhancing nanoaggregate formation. Formation of inclusion complexes was confirmed by DSC, FT-IR and 1H-NMR studies. A mixture of 15% (w/v) γCD and 8% (w/v) HPβCD was selected for formulation studies. It was concluded that formulations with aggregate sizes less than 1 µm and viscosity around 10–19 centipoises can be easily prepared using a mixture of CDs. Formulations containing polymeric drug/CD nanoaggregates represent an interesting strategy for enhanced topical delivery of nepafenac.

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Synthesis and properties of bismaleimide resins containing phthalide cardo and cyano groups

High Performance Polymers ◽

10.1177/0954008318782342 ◽

2018 ◽

Vol 31 (4) ◽

pp. 462-471 ◽

Cited By ~ 4

Author(s):

Siyang Liu ◽

Yuanying Wang ◽

Ping Chen ◽

Dongwei Xu ◽

Xuhai Xiong ◽

...

Keyword(s):

Thermal Polymerization ◽

Proton Nuclear Magnetic Resonance ◽

Resonance Spectroscopy ◽

Carbon Fiber Composites ◽

Scanning Calorimetry ◽

Chemical Structures ◽

Higher Temperature ◽

Interlaminar Shear ◽

Cyano Groups ◽

Bismaleimide Resins

Two novel n ≈ 1 oligomeric bismaleimide monomers containing phthalide cardo and cyano groups (PCBMI and MCBMI) were designed and synthesized. The chemical structures of the monomers were confirmed from proton nuclear magnetic resonance spectroscopy and Fourier transform infrared spectroscopy. Both BMIs exhibit good solubility in common organic solvents, enabling easy solution processing. Thermal curing behaviors of the monomers were investigated by differential scanning calorimetry, displaying broad exothermic peaks and large thermal processing windows. Furthermore, PCBMI/carbon fiber composites were prepared, with their thermal stability and mechanical properties investigated. Thermogravimetric analysis and test of interlaminar shear strength indicated that the thermal polymerization of cyano groups improved the heat resistance of BMI resins and enhanced the interfacial adhesion at higher temperature.

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Neuroendocrine Neoplasms: Identification of Novel Metabolic Circuits of Potential Diagnostic Utility

Cancers ◽

10.3390/cancers13030374 ◽

2021 ◽

Vol 13 (3) ◽

pp. 374

Author(s):

Beatriz Jiménez ◽

Mei Ran Abellona U ◽

Panagiotis Drymousis ◽

Michael Kyriakides ◽

Ashley K. Clift ◽

...

Keyword(s):

1H Nmr ◽

Cancer Metabolism ◽

Proton Nuclear Magnetic Resonance ◽

Neuroendocrine Neoplasms ◽

Resonance Spectroscopy ◽

Diagnostic Utility ◽

Signalling Molecules ◽

Prognostic Accuracy ◽

Diagnostic Potential ◽

Healthy Control

The incidence of neuroendocrine neoplasms (NEN) is increasing, but established biomarkers have poor diagnostic and prognostic accuracy. Here, we aim to define the systemic metabolic consequences of NEN and to establish the diagnostic utility of proton nuclear magnetic resonance spectroscopy (1H-NMR) for NEN in a prospective cohort of patients through a single-centre, prospective controlled observational study. Urine samples of 34 treatment-naïve NEN patients (median age: 59.3 years, range: 36–85): 18 had pancreatic (Pan) NEN, of which seven were functioning; 16 had small bowel (SB) NEN; 20 age- and sex-matched healthy control individuals were analysed using a 600 MHz Bruker 1H-NMR spectrometer. Orthogonal partial-least-squares-discriminant analysis models were able to discriminate both PanNEN and SBNEN patients from healthy control (Healthy vs. PanNEN: AUC = 0.90, Healthy vs. SBNEN: AUC = 0.90). Secondary metabolites of tryptophan, such as trigonelline and a niacin-related metabolite were also identified to be universally decreased in NEN patients, while upstream metabolites, such as kynurenine, were elevated in SBNEN. Hippurate, a gut-derived metabolite, was reduced in all patients, whereas other gut microbial co-metabolites, trimethylamine-N-oxide, 4-hydroxyphenylacetate and phenylacetylglutamine, were elevated in those with SBNEN. These findings suggest the existence of a new systems-based neuroendocrine circuit, regulated in part by cancer metabolism, neuroendocrine signalling molecules and gut microbial co-metabolism. Metabonomic profiling of NEN has diagnostic potential and could be used for discovering biomarkers for these tumours. These preliminary data require confirmation in a larger cohort.

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Preparation, Thermal, and Thermo-Mechanical Characterization of Polymeric Blends Based on Di(meth)acrylate Monomers

Polymers ◽

10.3390/polym13060878 ◽

2021 ◽

Vol 13 (6) ◽

pp. 878

Author(s):

Krystyna Wnuczek ◽

Andrzej Puszka ◽

Łukasz Klapiszewski ◽

Beata Podkościelna

Keyword(s):

Mechanical Analysis ◽

Attenuated Total Reflection ◽

Scanning Calorimetry ◽

Force Microscopy ◽

Chemical Structures ◽

Atomic Force ◽

Polymeric Blends ◽

Ft Ir ◽

Acrylate Monomers ◽

Synthesized Materials

This study presents the preparation and the thermo-mechanical characteristics of polymeric blends based on di(meth)acrylates monomers. Bisphenol A glycerolate diacrylate (BPA.GDA) or ethylene glycol dimethacrylate (EGDMA) were used as crosslinking monomers. Methyl methacrylate (MMA) was used as an active solvent in both copolymerization approaches. Commercial polycarbonate (PC) was used as a modifying soluble additive. The preparation of blends and method of polymerization by using UV initiator (Irqacure® 651) was proposed. Two parallel sets of MMA-based materials were obtained. The first included more harmless linear hydrocarbons (EGDMA + MMA), whereas the second included the usually used aromatic copolymers (BPA.GDA + MMA). The influence of different amounts of PC on the physicochemical properties was discussed in detail. Chemical structures of the copolymers were confirmed by attenuated total reflection–Fourier transform infrared (ATR/FT-IR) spectroscopy. Thermo-mechanical properties of the synthesized materials were investigated by means of differential scanning calorimetry (DSC), thermogravimetric (TG/DTG) analyses, and dynamic mechanical analysis (DMA). The hardness of the obtained materials was also tested. In order to evaluate the surface of the materials, their images were obtained with the use of atomic force microscopy (AFM).

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Preparation and properties of shape-stabilized phase change material cellulose benzoate-g-polyoxyethylene (2) hexadecyl ether with potential for thermal energy storage

Textile Research Journal ◽

10.1177/0040517518773379 ◽

2018 ◽

Vol 89 (8) ◽

pp. 1512-1521

Author(s):

Na Han ◽

Wenxin Zhang ◽

Xiufang Wang ◽

Xingxiang Zhang ◽

Wei Li ◽

...

Keyword(s):

Phase Transition ◽

Energy Storage ◽

Phase Change ◽

Thermal Energy ◽

Thermal Energy Storage ◽

Solid Phase ◽

Resonance Spectroscopy ◽

Thermal Reliability ◽

Scanning Calorimetry ◽

Chemical Structures

It is a worldwide challenge to efficiently use renewable resources to solve the current energy shortage. The existing cellulose-based material is incapable of proper power storage. In this study, a series of cellulose benzoate-g-polyoxyethylene (2) hexadecyl ether (CB-g-E2C16) solid–solid phase change materials were synthesized with cellulose as the skeleton and polyoxyethylene (2) hexadecyl ether (E2C16) as a functional side chain. The skeleton cellulose and benzoyl chloride restrict the free movement of the molecular chains of E2C16 above the phase transition temperature, leading to a solid–solid phase change. Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy were performed to investigate the chemical structures. The thermal energy-storage properties, thermal reliability and thermal stability of the CB-g-E2C16 were investigated by differential scanning calorimetry and thermogravimetry (TG) methods. The analysis results indicated that the E2C16 chains were successfully grafted onto the cellulose benzoate (CB) backbone and the copolymers exhibited typical solid–solid phase transition behavior. The enthalpy and degree of substitution of graft copolymers CB-g-E2C16 could be adjusted by changing the feeding ratio of the raw materials, reaction temperature and post-processing methods of CB. TG analysis results showed that the CB-g-E2C16 copolymers possessed good thermostability and they keep their stability up to 278℃. Compared with pure cellulose, CB-g-E2C16 copolymers could be dissolved in dimethyl sulfoxide and most of them could be dissolved in N, N-dimethylformamide.

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Quantitative Analysis of Apoptotic Cell Death Using Proton Nuclear Magnetic Resonance Spectroscopy

Blood ◽

10.1182/blood.v89.10.3778 ◽

1997 ◽

Vol 89 (10) ◽

pp. 3778-3786 ◽

Cited By ~ 106

Author(s):

Francis G. Blankenberg ◽

Peter D. Katsikis ◽

Richard W. Storrs ◽

Christian Beaulieu ◽

Daniel Spielman ◽

...

Keyword(s):

Nuclear Magnetic Resonance ◽

Cell Death ◽

Magnetic Resonance ◽

1H Nmr ◽

Signal Intensity ◽

Intensity Ratio ◽

Apoptotic Cell ◽

Proton Nuclear Magnetic Resonance ◽

Resonance Spectroscopy ◽

Signal Intensity Ratio

Abstract Quantification of apoptotic cell death in vivo has become an important area of investigation in patients with acute lymphoblastic leukemia (ALL). We have devised a noninvasive analytical method to estimate the percentage of apoptotic lymphoblasts in doxorubicin-treated Jurkat T-cell ALL cultures, using proton nuclear magnetic resonance spectroscopy (1H NMR). We have found that the ratio of the methylene (CH2 ) resonance (at 1.3 ppm) to the methyl (CH3 ) resonance (at 0.9 ppm) signal intensity, as observed by 1H NMR, is directly proportional to the percentage of apoptotic lymphoblasts in vitro. The correlation between the CH2/CH3 signal intensity ratio and the percentage of apoptotic lymphoblasts was optimal 24 to 28 hours after doxorubicin treatment (r2 = .947, N = 27 samples). There was also a direct temporal relationship between an increase in the CH2/CH3 signal intensity ratio and the onset of apoptosis as detected by nuclear morphologic analysis, fluorescein-annexin V flow cytometry, and DNA gel electrophoresis. Thin-layer chromatography confirmed that a dynamic and/or compositional change of the plasma membrane, rather than increases in lipase activity or fatty acid production, appears to account for the increase in the CH2/CH3 signal intensity ratio during apoptosis. 1H NMR may have clinical utility for the early noninvasive assessment of chemotherapeutic efficacy in patients with ALL.

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Analysis of Bio-Based Fatty Esters PCM’s Thermal Properties and Investigation of Trends in Relation to Chemical Structures

Applied Sciences ◽

10.3390/app9020225 ◽

2019 ◽

Vol 9 (2) ◽

pp. 225 ◽

Cited By ~ 5

Author(s):

Rebecca Ravotti ◽

Oliver Fellmann ◽

Nicolas Lardon ◽

Ludger Fischer ◽

Anastasia Stamatiou ◽

...

Keyword(s):

Thermal Properties ◽

Phase Change ◽

Energy Demand ◽

Phase Change Materials ◽

Arachidic Acid ◽

Resonance Spectroscopy ◽

Scanning Calorimetry ◽

Fatty Esters ◽

Latent Heat Storage ◽

Chemical Structures

As global energy demand increases while primary sources and fossil fuels’ availability decrease, research has shifted its focus to thermal energy storage systems as alternative technologies able to cover for the mismatch between demand and supply. Among the different phase change materials available, esters possess particularly favorable properties with reported high enthalpies of fusion, low corrosivity, low toxicity, low supercooling, thermal and chemical stability as well as biodegradability and being derived from renewable feedstock. Despite such advantages, little to no data on the thermal behavior of esters is available due to low commercial availability. This study constitutes a continuation of previous works from the authors on the investigation of fatty esters as novel phase change materials. Here, methyl, pentyl and decyl esters of arachidic acid, and pentyl esters of myristic, palmitic, stearic and behenic acid are synthesized through Fischer esterification with high purities and their properties are studied. The chemical structures and purities are confirmed through Attenuated Total Reflectance Infrared Spectroscopy, Gas Chromatography coupled with Mass Spectroscopy and Nuclear Magnetic Resonance Spectroscopy, while the determination of the thermal properties is performed through Differential Scanning Calorimetry and Thermogravimetric Analysis. In conclusion, some correlations between the melting temperatures and the chemical structures are discovered, and the fatty esters are assessed based on their suitability as phase change materials for latent heat storage applications.

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