Gel Permeation Chromatography Method Research Articles

Oxygen-containing compounds in polydimethylsilanes and -carbosilanes

An analysis of fractions extracted from polydimethylsilanes, as well as distillates obtained during the synthesis of poly(oligo)carbosilanes was carried out. By the methods of gel permeation chromatography and chromatography-mass spectrometry, the range of molecular weights in extracts and distillates, the composition and structure of compounds, as well as the sequence of their retention times on the chromatographic column were determined. It was established that the compounds extracted from polydimethylsilanes are low molecular weight cycles containing methylsilane and/or methylsiloxane units. In distillates, compared with extracts, the number of low molecular weight compounds containing individual or mixed methylsilane, carbosilane and siloxane units increases.

Measuring Erosion of Biodegradable Polymers in Brimonidine Drug Delivery Implants by Quantitative Proton NMR Spectroscopy (q-HNMR)

Erosion of biodegradable polymeric excipients, such as polylactic acid (PLA) and polylactic-co-glycolic acid (PLGA), is generally characterized by microbalance for the remaining mass of PLA and/or PLGA and Gel Permeation Chromatography (GPC) for molecular weight (MW) decrease. For polymer erosion studies of intravitreal sustained release brimonidine implants, however, both microbalance and GPC present several challenges. Mass loss measurement by microbalance does not have specificity for excipient polymers and drug substances. Accuracy of the remaining mass by weighing could also be low due to sample mass loss through retrieval-drying steps, especially at later drug release (DR) time points. When measuring the decrease of polymer MW by GPC, trace amounts of polymeric degradants (oligomers and/or monomers) trapped inside the implants during DR tests may not be measurable due to sensitivity limitations of the GPC detector and column MW range. Previous efforts to measure remained PLGA weight of dexamethasone micro-implants using qNMR with external calibration have been performed, however, these measurements do not account for chemical structure changes (i.e. LA to GA ratio changes from time zero) of PLGA implants during drug release tests. Here, a qNMR method with an internal standard was developed to monitor the following changes in micro-implants during drug release tests: 1. The remaining overall PLA/PLGA mass. 2. The remaining lactic acid (LA), glycolic acid (GA) unit and PLGA's lauryl ester end group percentages. 3. The trace content of PLA/PLGA oligomers as degradants retained in the implants. Unlike microbalance analysis, qNMR has both specificity for drug substance, excipient polymer, and accuracy due to minimal implant loss during sample preparation. Compared to the overall PLA/PLGA remaining mass generally monitored in erosion studies, the percentage of remaining LA, GA, and the ester end group provide more information about the microstructure change (such as hydrophobicity) of PLA/PLGA. Additionally, the qNMR method can complement GPC methods by measuring the change of remaining PLA and PLGA oligomer concentrations in brimonidine implants, with tenfold less sample and no MW cutoff. The qNMR method can be used as a sensitive tool for both polymer excipient characterization and kinetics studies of brimonidine implant erosion.

Polypy: A Framework to Interpret Polymer Properties from Mass Spectroscopy Data.

Mass spectroscopy (MS) is a robust technique for polymer characterization, and it can provide the chemical fingerprint of a complete sample regarding polymer distribution chains. Nevertheless, polymer chemical properties such as polydispersity (Pd), average molecular mass (Mn), weight average molecular mass (Mw) and others are not determined by MS, as they are commonly characterized by gel permeation chromatography (GPC). In order to calculate polymer properties from MS, a Python script was developed to interpret polymer properties from spectroscopic raw data. Polypy script can be considered a peak detection and area distribution method, and represents the result of combining the MS raw data filtered using Root Mean Square (RMS) calculation with molecular classification based on theoretical molar masses. Polypy filters out areas corresponding to repetitive units. This approach facilitates the identification of the polymer chains and calculates their properties. The script also integrates visualization graphic tools for data analysis. In this work, aryl resin (poly(2,2-bis(4-oxy-(2-(methyloxirane)phenyl)propan) was the study case polymer molecule, and is composed of oligomer chains distributed mainly in the range of dimers to tetramers, in some cases presenting traces of pentamers and hexamers in the distribution profile of the oligomeric chains. Epoxy resin has Mn = 607 Da, Mw = 631 Da, and polydispersity (Pd) of 1.015 (data given by GPC). With Polypy script, calculations resulted in Mn = 584.42 Da, Mw = 649.29 Da, and Pd = 1.11, which are consistent results if compared with GPC characterization. Additional information, such as the percentage of oligomer distribution, was also calculated and for this polymer matrix it was not possible to retrieve it from the GPC method. Polypy is an approach to characterizing major polymer chemical properties using only MS raw spectra, and it can be utilized with any MS raw data for any polymer matrix.

Composition and mitogenic activity of polysaccharide from Solanum tuberosum L.

Solanum tuberosum polysaccharide (STP) was isolated from the water extract of Solanum tuberosum L. and purified by ion-exchange and gel-filtration chromatography. Its molecular weight was determined by using gel permeation chromatography method and high performance liquid chromatography technique and its monosaccharide composition was analyzed using high performance liquid chromatography and gas chromatography with a flame ionization detector and a capillary column. It was shown that STP was consisted of galactose (Gal) and arabinose (Ara) (37.5 and 23.5%, respectively), along with uronic acids (9.7%), glucose monosaccharide residues (15%) and proteins (no less than 9%). The molecular weight of STP was 70 kDa. The Fourier-transform infrared technique was used for structural analysis of STP. The mitogenic activity of extracted polysaccharide is comparable to that of lipopolysaccharide.

Inonotus obliquus polysaccharide are linear molecules that alter the abundance and composition of intestinal microbiota in Sprague Dawley rats.

The macromolecular polysaccharide Inonotus obliquus polysaccharide (IOP) is composed of various monosaccharides, and it could modulate the composition and diversity of intestinal flora. However, its impact on the intestinal flora in rats of different genders remains unclear. Therefore, this study aims to investigate the structural changes of IOP and its effects on the intestinal flora after administration in male and female rats. In this study, the molecular weight and purity of IOP were analyzed by high-performance gel permeation chromatography (HPGPC) and phenol sulfuric acid method, and NMR was used to confirm the chemical structure of IOP. Sex hormone [testosterone (T) and estradiol (E2)] levels and intestinal microbial changes were detected by enzyme-linked immunosorbent assay (ELISA) and 16S rRNA, respectively, after gavage of IOP (100 mg/kg) in male and female Sprague Dawley (SD) rats. HPGPC analysis showed that the average molecular weight (Mw) of IOP was 4,828 Da, and the total sugar content of the purified IOP was 96.2%, indicating that the polysaccharide is of high purity. NMR revealed that IOP is a linear macromolecule with an α-D-type glucose backbone. The results of ELISA and 16S rRNA showed that the IOP increased the abundance of beneficial bacteria, such as Clostridia_UCG-014 and Prevotellaceae_NK3B31, and reduced that of harmful bacteria, such as Colidextribacter and Desulfobacterota in the intestine of both male and female rats, and IOP changed the levels of sex hormones in male and female rats. Further analyses revealed that the increase in alpha diversity was higher in male than female rats. α diversity and β diversity revealed a significant difference in the composition of cecal microbiota between male and female rats in the control group, but IOP intake reduced this difference. Meanwhile, α analysis revealed a change in the composition of bacterial flora was more stable in male than female rats. This study enhances our comprehension of the IOP structure and elucidates the alterations in intestinal flora following IOP administration in rats of varying genders. Nonetheless, further investigation is warranted to explore the specific underlying reasons for these discrepancies.

Eighteen Novel Bioactive Peptides from Monkfish (Lophius litulon) Swim Bladders: Production, Identification, Antioxidant Activity, and Stability.

In the study, papain was chosen from five proteases to hydrolyze proteins of monkfish swim bladders for effectively utilizing monkfish (Lophius litulon) processing byproducts, and the hydrolysis conditions of papain were optimized as hydrolysis temperature of 65 °C, pH 7.5, enzyme dose 2.5% and time 5 h using single-factor and orthogonal experiments. Eighteen peptides were purified from the swim bladder hydrolysate of monkfish by ultrafiltration and gel permeation chromatography methods and identified as YDYD, QDYD, AGPAS, GPGPHGPSGP, GPK, HRE, GRW, ARW, GPTE, DDGGK, IGPAS, AKPAT, YPAGP, DPT, FPGPT, GPGPT, GPT and DPAGP, respectively. Among eighteen peptides, GRW and ARW showed significant DPPH· scavenging activities with EC50 values of 1.053 ± 0.003 and 0.773 ± 0.003 mg/mL, respectively; YDYD, QDYD, GRW, ARW and YPAGP revealed significantly HO· scavenging activities with EC50 values of 0.150 ± 0.060, 0.177 ± 0.035, 0.201 ± 0.013, 0.183 ± 0.0016 and 0.190 ± 0.010 mg/mL, respectively; YDYD, QDYD, ARW, DDGGK and YPAGP have significantly O2-· scavenging capability with EC50 values of 0.126 ± 0.0005, 0.112 ± 0.0028, 0.127 ± 0.0002, 0.128 ± 0.0018 and 0.107 ± 0.0002 mg/mL, respectively; and YDYD, QDYD and YPAGP showed strong ABTS+· scavenging ability with EC50 values of 3.197 ± 0.036, 2.337 ± 0.016 and 3.839 ± 0.102 mg/mL, respectively. YDYD, ARW and DDGGK displayed the remarkable ability of lipid peroxidation inhibition and Ferric-reducing antioxidant properties. Moreover, YDYD and ARW can protect Plasmid DNA and HepG2 cells against H2O2-induced oxidative stress. Furthermore, eighteen isolated peptides had high stability under temperatures ranging from 25-100 °C; YDYD, QDYD, GRW and ARW were more sensitive to alkali treatment, but DDGGK and YPAGP were more sensitive to acid treatment; and YDYD showed strong stability treated with simulated GI digestion. Therefore, the prepared antioxidant peptides, especially YDYD, QDYD, GRW, ARW, DDGGK and YPAGP from monkfish swim bladders could serve as functional components applied in health-promoting products because of their high-antioxidant functions.

High-Molecular-Weight Exopolysaccharides Production from Tuber borchii Cultivated by Submerged Fermentation

Truffles are known worldwide for their peculiar taste, aroma, and nutritious properties, which increase their economic value. However, due to the challenges associated with the natural cultivation of truffles, including cost and time, submerged fermentation has turned out to be a potential alternative. Therefore, in the current study, the cultivation of Tuber borchii in submerged fermentation was executed to enhance the production of mycelial biomass, exopolysaccharides (EPSs), and intracellular polysaccharides (IPSs). The mycelial growth and EPS and IPS production was greatly impacted by the choice and concentration of the screened carbon and nitrogen sources. The results showed that sucrose (80 g/L) and yeast extract (20 g/L) yielded maximum mycelial biomass (5.38 ± 0.01 g/L), EPS (0.70 ± 0.02 g/L), and IPS (1.76 ± 0.01 g/L). The time course analysis of truffle growth revealed that the highest growth and EPS and IPS production was observed on the 28th day of the submerged fermentation. Molecular weight analysis performed by the gel permeation chromatography method revealed a high proportion of high-molecular-weight EPS when 20 g/L yeast extract was used as media and the NaOH extraction step was carried out. Moreover, structural analysis of the EPS using Fourier-transform infrared spectroscopy (FTIR) confirmed that the EPS was β-(1-3)-glucan, which is known for its biomedical properties, including anti-cancer and anti-microbial activities. To the best of our knowledge, this study represents the first FTIR analysis for the structural characterization of β-(1-3)-glucan (EPS) produced from Tuber borchii grown in submerged fermentation.

Understanding the influences of poplar recalcitrance during combinatorial pretreatment on ethanol production

A combinatorial pretreatment process with liquid hot water (LHW) and sodium hydroxide were explored to compare the potential impact of each pretreatment on ethanol production from poplar. The physicochemical properties and ultrastructure of substrates before and after pretreatment were characterized to highlight their impacts on subsequent simultaneous saccharification and fermentation (SSF). The results revealed that 200 °C LHW combinatorial 1% NaOH pretreatment achieved the highest ethanol yield of 50.90% with 22.71 g/L of ethanol concentration, which was strongly correlated with the removal of hemicellulose and delignification. Then, the key factors related to biomass recalcitrance, such as cellulose crystallinity index (CrI), accessibility and degree of polymerization (DP) were analyzed by X-ray diffraction (XRD), Simons' staining and Gel Permeation Chromatography (GPC) method, respectively. After pretreatment, an increased cellulose CrI/accessibility and decreased cellulose DP were obtained in pretreated poplar, which could effectively improve the subsequent fermentation yield, and in this study, hemicellulose/lignin removal and cellulose accessibility exhibited positive correlation with the adsorption capability of cellulase, whereas, cellulose DP were negatively potential associated with SSF. This work will provide important guidance for better understanding the influences of biomass recalcitrance on ethanol production during the pretreatment process.

Molecular weight determination of low molecular weight hyaluronic acid and chondroitin sulfate by gel permeation chromatography

Low molecular weight (LWM) hyaluronic acid (HA) and chondroitin sulfate (CS) have a wide range of applications. To determine their molecular weight (MW), we developed a gel permeation chromatography (GPC) method, which is calibrated based on serrated peaks in the chromatograms. MW calibrants were obtained from the enzymolysis of HA and CS using hyaluronidase. The identical structure of calibrants and samples ensured the soundness of the method. The highest confidence MWs were up to 14,454 and 14,605 for HA and CS, respectively, and the standard curves showed very high correlation coefficients. Thanks to the changeless relationship between MW and its contribution to the GPC integral, the second calibration curves could be derived via one GPC column, also embodied correlation coefficients of >0.9999. The discrepancies of MW values were minuscule, and the measurement of a sample could be conducted in <30 min. The accuracy of the method was verified using LWM heparins, and the measured Mw values showed a 1.2 %–2.0 % error relative to pharmacopeia results. The MW results obtained for LWM-HA and LWM-CS samples were also consistent with the results obtained by multiangle laser light scattering. The method was also verified be able to measure the very low MWs.

Quality consistency evaluation of commercial Prunellae Spica by integrating determination of secondary metabolites and saccharides

Prunellae Spica (PS) is a commonly used medicinal herb in China. Secondary metabolites and saccharides are major bioactive components of PS. However, holistic quality consistency of commercial PS is ambiguous due to lack of comprehensive evaluation methods and reliable quality control markers. Integrating multiple chromatographic and chemometric methods to comprehensively evaluate the holistic quality of PS. Ultrahigh-performance liquid chromatography coupled with triple-quadrupole tandem mass spectrometry (UPLC-TQ-MS/MS) was applied to quantify 12 secondary metabolites of PS. High-performance liquid chromatography coupled with photodiode array/evaporative light scattering detection (HPLC-PDA/ELSD) and high-performance gel permeation chromatography (HPGPC) methods were used to characterise the saccharides. Multivariate statistical analysis was adopted to evaluate the quality consistency of commercial PS and explore the potential quality control markers. The contents of secondary metabolites and saccharides were significantly different among commercial PS. All samples could be classified into three groups with ferulic acid, protocatechualdehyde, gallic acid, ursolic acid/oleanolic acid, sucrose, p-coumaric acid, chlorogenic acid as the major contributing components responsible for the difference. The content of rosmarinic acid was correlated with that of betulinic acid, hyperposide, chlorogenic acid, rutin, caffeic acid, p-coumaric acid and glucose, whereas polysaccharides, ferulic acid, protocatechualdehyde and ursolic acid/oleanolic acid, quercetin, sucrose and majority monosaccharides were not. The holistic quality of commercial PS was inconsistent. Together with rosmarinic acid, ferulic acid, protocatechualdehyde, ursolic acid/oleanolic acid, polysaccharides and sucrose might be recommended as potential quality control markers for the holistic quality control of PS.

Polydimethylsiloxanes with Grafted Dibenzoylmethanatoboron Difluoride: Synthesis and Properties.

A method for the preparation of polydimethylsiloxanes with grafted methoxy-substituted dibenzoylmethanatoboron difluoride has been described. The structures of prepared polymers were confirmed using NMR, IR spectroscopy and gel permeation chromatography methods. Their thermal properties were investigated using thermal gravimetric analysis, differential scanning calorimetry and thermomechanical analysis. The prepared polymers had good thermal (Td5% up to 393 °C) and thermo-oxidative (Td5% = 413 °C) stability. The polymers started to transit in a viscous flow state at about 40 °C (for 3 a) and at about 20 °C (for 3 b). The viscoelastic characteristics of prepared polymers were determined in the sinusoidal oscillating vibrations mode. It was shown that the studied polymers at low frequencies at room temperature are viscoelastic fluids (G′ < G″). Increasing the frequency led to inversion (crossover) of dependences G′ and G″, which indicated the transition of polymers from viscous to elastomeric behavior characteristics, and the beginning of the formation of a physical network. Optical properties were studied using electron absorption, steady-state and time-resolved fluorescence spectroscopy. It was shown that intramolecular H-dimers exist in the ground state. The polymers studied had a bright fluorescence in the solution and in the solid state, consisting of bands of monomer and excimer emission. Thermally-activated delayed fluorescence was observed in the solution and the solid state. The prepared polymers possess intriguing properties that make them useful as optical materials, sensors or imaging agents.

Molecular Characterization and Biocompatibility of Exopolysaccharide Produced by Moderately Halophilic Bacterium Virgibacillus dokdonensis from the Saltern of Kumta Coast.

The use of natural polysaccharides as biomaterials is gaining importance in tissue engineering due to their inherent biocompatibility. In this direction, the present study aims to explore the structure and biocompatibility of the EPS produced by Virgibacillus dokdonensis VITP14. This marine bacterium produces 17.3 g/L of EPS at 96 h of fermentation. The EPS was purified using ion exchange and gel permeation chromatographic methods. The porous web-like structure and elemental composition (C, O, Na, Mg, P, S) of the EPS were inferred from SEM and EDX analysis. AFM analysis revealed spike-like lumps with a surface roughness of 84.85 nm. The zeta potential value of −10 mV indicates the anionic nature of the EPS. Initial molecular characterization showed that the EPS is a heteropolysaccharide composed of glucose (25.8%), ribose (18.6%), fructose (31.5%), and xylose (24%), which are the monosaccharide units in the HPLC analysis. The FTIR spectrum indicates the presence of functional groups/bonds typical of EPSs (O-H, C-H, C-O-H, C-O, S=O, and P=O). The polymer has an average molecular weight of 555 kDa. Further, NMR analysis revealed the monomer composition, the existence of two α- and six β-glycosidic linkages, and the branched repeating unit as → 1)[α-D-Xylp-(1 → 2)-α-D-Glcp-(1 → 6)-β-D-Glcp-(1 → 5)]-β-D-Frup-(2 → 2)[β-D-Xylp-(1 → 4)]-β-D-Xylp-(1 → 6)-β-D-Fruf-(2 → 4)-β-D-Ribp-(1 →. The EPS is thermally stable till 251.4 °C. X-ray diffraction analysis confirmed the semicrystalline (54.2%) nature of the EPS. Further, the EPS exhibits significant water solubility (76.5%), water-holding capacity (266.8%), emulsifying index (66.8%), hemocompatibility (erythrocyte protection > 87%), and cytocompatibility (cell viability > 80% on RAW264.7 and keratinocyte HaCaT cells) at higher concentrations and prolongs coagulation time in APTT and PT tests. Our research unveils the significant biocompatibility of VITP14 EPS for synthesizing a variety of biomaterials.

ɛ-caprolactone and pentaerythritol derived oligomer for rigid polyurethane foams preparation

Copolymerization of pentaerythritol with five equivalents of ɛ-caprolactone leads to tetra-functional branched oligomer terminated with hydroxyl groups. The product was characterized by elemental analysis, IR and NMR spectroscopy, gel permeation chromatography and physical methods to determine viscosity, density and surface tension. The oligomer was then used to obtain rigid polyurethane foam. The foam was characterized by physicochemical methods to determine: apparent density, water uptake, polymerization shrinkage, heat conductance coefficient, thermal stability, compression strength and biodegradation. The foam obtained from this oligomer have the properties similar to classic rigid polyurethane foams but enhanced thermal resistance. It can stand long time heating at 175°C, while its compression strength increases upon thermal exposure. The foam and oligomer are biodegradable; the oligomer is fully decomposed within 28 days in soil, while the foam obtained from it is in the same conditions degradable up to 28% of initial mass.

(Invited) Measuring Molecular Weight of Poly(methyl methacrylate) through Electrochemistry

Rapid measurement of the molecular weight of a polymer is a crucial task both scientifically and industrially. Usually, the molecular weight of a polymer has been determined using the gel permeation chromatography (GPC), viscosity method (Ostwald, and Ubbelohde), nuclear magnetic resonance (NMR) spectroscopy, and other methods. However, they all share a critical weakness in that it is not possible to perform rapid measurement because of the long analysis times. To overcome this drawback, we propose a novel method for estimating polymer molecular weight using electrochemistry. In this study, poly(methyl methacrylate) formed by reversible addition-fragmentation chain transfer (RAFT) polymerization was considered as a model system. As polymerization progressed, a gradual decrease in steady-state current was observed in cyclic voltammetry. The decrease in current was compared to the molecular weights of the polymer obtained using the conventional methods of GPC and NMR. Therefore, the polymer molecular weight can be determined accurately and rapidly by measuring the current.

Modification of Poly(Styrene‐co‐Acrylonitrile) with Tetrazine by Inverse Electron Demand Diels‐Alder Reaction

AbstractPoly(styrene‐co‐acrylonitrile) [P(SAN)] copolymer was obtained by using styrene and acrylonitrile monomers via free‐radical polymerization. The tetrazine groups were formed in the P(SAN) copolymer backbone by using 2‐fluorobenzyl cyanide, hydrazine hydrate, zinc iodide as the catalyst, and sodium nitrile. The tetrazine groups in the copolymer backbone were modified using trans‐cyclooctenol by the Inverse Electron Demand Diels‐Alder reaction. The spectroscopic properties of the obtained products were determined by Fourier transform infrared and proton nuclear magnetic resonance and their thermal properties were determined by thermogravimetric analysis and differential scanning calorimetry techniques. The average molecular weights of the synthesized polymers were defined by using gel permeation chromatography method.

Confronting the Challenge of Cellulose Molecular Weight Measurement: An Accurate, Rapid, and Universal Method with Ionic Liquid as an Additive.

Molecular weight parameters are the key fundamental information of polymer materials, but the accurate characterization of the molecular weight of cellulose is extremely difficult due to its strong hydrogen bonding network. Herein, we demonstrated two new methods to accurately and rapidly measure the molecular weight parameters of cellulose by using 1-butyl-3-methylimidazolium acetate (BmimAc) ionic liquid (IL) as an additive. Cellulose is rapidly dissolved in BmimAc/DMSO (1:1, w/w) at room temperature at first. Then, DMAc is added to dilute the solution, and finally, the molecular weight and molecular weight distribution of cellulose samples are measured by the gel permeation chromatography (GPC) method with BmimAc/DMSO/DMAc (1:1:18, w/w) as the mobile phase. Such a simple method is suitable to all kinds of cellulose samples and exhibits an extremely high analytical efficiency which is 50 times higher than the previous GPC methods. In addition, a viscosity method that is available for industrial application was proposed by using the BmimAc/DMSO/DMAc (1:1:8, w/w) system with low viscosity. The relationship between the intrinsic viscosity of the cellulose/BmimAc/DMSO/DMAc solution and the molecular weight of cellulose is well established and is applicable to cellulose samples of Mw = 4.5 × 104 to 1.8 × 106, which is the widest applicable range among the reported viscosity methods. Overall, two new methods based on the use of BmimAc as an additive have many advantages, such as wide applicable range, simple preparation process, mild dissolution condition, no degradation or aggregation of cellulose, high accuracy, fast detection, and low IL consumption, overcoming the existing problems in the traditional methods. It is expected to be used as a standard procedure to characterize the molecular weight of cellulose in academia and industries.

Biodegradable Star-Shaped Poly(lactic acid): Synthesis, Characterization and Its Reaction Kinetics

Biodegradable four-arm star-shaped poly(lactic acid) (4sPLA) was synthesized from l-Lactic acid (l-LA) and pentaerythritol (PENTA), and the polymerization kinetics was studied. The effects of reaction time, reaction temperature and molar ratio on the polymerization of 4sPLA were discussed. The molecular structure of 4sPLA was characterized by Fourier transform infrared spectroscopy (FTIR) and 1H nuclear magnetic resonance spectra (1H-NMR). The results showed that the optimum reaction conditions were as follows: the molar ratio of l-LA to PENTA was 12:1, and the polymerization reaction occurred at 160 ℃ for 5 h. Gel permeation chromatography method was used to determine the polymerization kinetics of 4sPLA consistent with the first-order reaction kinetics.

Acrylate polymers of triazine containing chalcone moiety: Synthesis, characterization, reactivity ratio and photocrosslinking studies

Acrylate monomer ((4-(3-(4-((4-(4-(3-(2,4-dichlorophenyl)-3-oxoprop-1-en-1-yl)phenoxy)-6-((4-nitrophenyl)amino)-1,3,5-triazin-2-yl)oxy)phenyl)-3-oxoprop-1-en-1-yl)phenyl acrylate (DTCP) is prepared and used to prepare poly (DTCP) and its copolymer poly (DTCP-co-HEA) and poly (DTCP-co-S) using 2-hydroxyethyl acrylate (HEA), styrene (S) by solution polymerization technique. Infrared spectroscopy (FT-IR), proton Nucleharmar Magnetic Resonance (1H NMR), and UV-Visible techniques are used to identify the synthesized polymers. Gel permeation chromatography method is used to determine the polymer’s weight average molecular weight, which is found to be around 10000 g/mol. According to the Thermo Gravimetric Analysis study, the synthesized polymers go through single stage decomposition centered at 340°C. The polymer reactivity ratio is found using well known Finemann-Ross (F-R), Kelen-Tudos (K-T), and extended Kelen-Tudos (ex.K-T) methods. The reactivity of the commercial monomers (HEA or S) is found to be higher than that of synthesized monomer, according to our findings. The photocrosslinking rate of the synthesized polymers is determined using a UV visible spectroscopic method and found to be high for polymer having HEA unit.

Effects of Radiation sterilization Dose on the Molecular Weight and Gelling Properties of Commercial Alginate Samples

To estimate the molecular weight (Mw) and gelling properties, a total of 26 alginate samples consisting of control (n = 13) and 15 kGy γ-irradiated (n = 13) samples were characterized through viscometric and gel permeation chromatography (GPC-MALLS) methods. Based on the observations, a remarkable decrease in the intrinsic viscosity of all samples of alginates was evident due to the effects of radiation, with a linear relationship between viscosity and concentration in 0.01 M NaCl solution. The correlation among the Mw, percentage mass recovery, radii of gyration (Rz/Rg), and percentage reduction of Mw assessed by GPC was significant. The Mw decreased dramatically (from 3.1 × 105 to 0.49 × 105 mole/g in sample no. 12) by the effect of radiation with momentous relation to the % reduction of the molecular weight. The highest molecular weight reduction (84%), which is the most sensitive to γ-radiation, and the average reduction rate was ≥50%. The mass recovery was 100% obtained from samples no. 1,3,4,5,7,12, and 13, while the rest of the samples’ recovery rate was significantly higher. The reduction rate of mass molecular weight (Mw) is higher than the average molecular weight (Mv), but they showed a sensitivity towards radiation, consequently their performance are different from each other. The stability test was performed as a critical behaviour in the control, recurrently same as in the irradiated samples. Thus, the sterilization dose of 15 kGy for the Mw distribution, and subsequently for the characterization, was significantly effective.

Development of Comprehensive Analysis of Pyrolysis Products for Lignocellulose Raw Materials and Sludge Sediments by Chromatographic Methods

This paper presents a study of the pyrolysis products organic raw materials (bio-oil and sludge sediments of treatment facilities) by chromatographic methods. A feature of the work is to optimize the sample preparation procedure by fractionating the pyrolysis products. Using the method of gel permeation chromatography, molecular weight distribution of pyrolysis products was assessed. Determination of the water content in these objects (by Karl Fischer titration) was used to assess the possibility of their direct analysis by gas chromatography. A sample of sludge pyrolysis and several fractions obtained from a bio-oil sample were analyzed. By the method of two-dimensional gas chromatography, where a selfdeveloped column based on an ionic liquid was used as the first measurement column, the pyrolysate of sludge sediments and the ether fraction of bio-oil were analyzed. The obtained chromatograms and quantitative results are presented