scholarly journals Degradable Polymer Stars Based on Tannic Acid Cores by ATRP

Polymers ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 752 ◽  
Author(s):  
Julia Cuthbert ◽  
Saigopalakrishna S. Yerneni ◽  
Mingkang Sun ◽  
Travis Fu ◽  
Krzysztof Matyjaszewski
Keyword(s):  
Tannic Acid ◽  
Molar Mass ◽  
Gel Permeation Chromatography ◽  
Degradable Polymers ◽  
Degradable Polymer ◽  
Cytotoxicity Assays ◽  
Before And After ◽  
Phenolic Esters ◽  
Ft Ir ◽  
Waste Accumulation

Degradable polymers are crucial in order to reduce plastic environmental pollution and waste accumulation. In this paper, a natural product, tannic acid was modified to be used as a polymer star core. The tannic acid was modified with atom transfer radical polymerization (ATRP) initiators and characterized by 1H NMR, FT-IR, and XPS. Twenty-five arm polymer stars were prepared by photoinduced ATRP of poly(methyl methacrylate) (PMMA) or poly(oligo(ethylene oxide) methacrylate) (molar mass Mw = 300 g/mol) (P(OEO300MA)). The polymer stars were degraded by cleaving the polymer star arms attached to the core by phenolic esters under mild basic conditions. The stars were analyzed before and after degradation by gel permeation chromatography (GPC). Cytotoxicity assays were performed on the P(OEO300MA) stars and corresponding degraded polymers, and were found to be nontoxic at the concentrations tested.

Characterization of MWLs from Tamarix ramosissima isolated before and after hydrothermal treatment by spectroscopical and wet chemical methods

Holzforschung ◽  
2012 ◽  
Vol 66 (3) ◽  
Author(s):  
Ling-Ping Xiao ◽  
Zheng-Jun Shi ◽  
Feng Xu ◽  
Run-Cang Sun
Keyword(s):  
Hydrothermal Treatment ◽  
Quantum Coherence ◽  
Gel Permeation Chromatography ◽  
Tamarix Ramosissima ◽  
Main Reaction ◽  
Aryl Ether ◽  
Before And After ◽  
Coherence Spectroscopy ◽  
Ft Ir

Abstract To improve enzymatic hydrolysis, hydrothermal treatment was carried out on the shrub Tamarix ramosissima. Milled wood lignin (MWL) was isolated from T. ramosissima stems before and after hydrothermal treatment, and its chemical structure was characterized by carbohydrate analysis, elemental analysis, methoxy group determination, FT-IR spectroscopy, quantitative 13C NMR spectroscopy, 2D heteronuclear single quantum coherence spectroscopy, and gel permeation chromatography. The analyses confirmed that T. ramosissima MWL is very rich in syringyl units. It was found that the main reaction responsible for the lignin degradation is the homolytic cleavage of aryl-ether bonds resulting in a reduced amount of β-O-4′ interlinkages and, as a consequence, in elevated amounts of β-β′ and β-5′ linkages. The MWL isolated from the pretreated solid residue was more condensed and had a lower molecular weight than the MWL isolated from untreated material.

scholarly journals Molar mass determination of lignins and characterization of their polymeric structures by multi-detector gel permeation chromatography

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Evamaria C. Gaugler ◽  
Wolfgang Radke ◽  
Andrew P. Vogt ◽  
Dawn A. Smith
Keyword(s):  
Molar Mass ◽  
Lithium Bromide ◽  
Gel Permeation Chromatography ◽  
Mass Determination ◽  
Organosolv Lignin ◽  
Gel Permeation ◽  
Softwood Kraft Lignin ◽  
Polymeric Structures

AbstractMolar masses, Mark-Houwink-Sakurada (MHS) exponents, and refractive index increments (dn/dc) for three lignins were determined without derivatization by multi-detector gel permeation chromatography (GPC) in dimethylformamide (DMF) with 0.05 M lithium bromide (LiBr). The lack of effectiveness of fluorescence filters on molar mass determination by GPC-multi-angle laser light scattering (MALS) was confirmed for softwood kraft lignin (Indulin AT) and revealed for mixed hardwood organosolv lignin (Alcell) as well as soda straw/grass lignin (Protobind 1000). GPC with viscometry detection confirmed that these lignins were present as compact molecules. The MHS exponent α for Indulin AT and Alcell was in the order of 0.1. Additionally, the intrinsic viscosity of Protobind 1000 for a given molar mass was much lower than that of either Alcell or Indulin AT. This is the first report of dn/dc values for these three lignins in DMF with 0.05 M LiBr.

scholarly journals Fast Preparation of High-Performance Wood Materials Assisted by Ultrasonic and Vacuum Impregnation

Forests ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 567
Author(s):  
Hong Yang ◽  
Mingyu Gao ◽  
Jinxin Wang ◽  
Hongbo Mu ◽  
Dawei Qi
Keyword(s):  
Mechanical Properties ◽  
High Performance ◽  
Mechanical Tests ◽  
Vacuum Impregnation ◽  
Natural Forests ◽  
Ultrasonic Pretreatment ◽  
Fast Growing ◽  
Before And After ◽  
New Material ◽  
Ft Ir

In the absence of high-quality hardwood timber resources, we have gradually turned our attention from natural forests to planted fast-growing forests. However, fast-growing tree timber in general has defects such as low wood density, loose texture, and poor mechanical properties. Therefore, improving the performance of wood through efficient and rapid technological processes and increasing the utilization of inferior wood is a good way to extend the use of wood. Densification of wood increases the strength of low-density wood and extends the range of applications for wood and wood-derived products. In this paper, the effects of ultrasonic and vacuum pretreatment on the properties of high-performance wood were explored by combining sonication, vacuum impregnation, chemical softening, and thermomechanical treatments to densify the wood; then, the changes in the chemical composition, microstructure, and mechanical properties of poplar wood before and after treatment were analyzed comparatively by FT-IR, XRD, SEM, and mechanical tests. The results showed that with ultrasonic pretreatment and vacuum impregnation, the compression ratio of high-performance wood reached its highest level and the MOR and MOE reached their maximums. With the help of this method, fast-growing softwoods can be easily prepared into dense wood materials, and it is hoped that this new material can be applied in the fields of construction, aviation, and automobile manufacturing.

Synthesis, characterization and corrosion protection properties of polyN-(p-bromophenyl)-2-methacrylamide-co-glycidyl methacrylate on low nickel stainless steel

2011 ◽  
Vol 31 (2-3) ◽  
Author(s):  
Sakvai Mohammed Safiullah ◽  
Deivasigamani Thirumoolan ◽  
Kottur Anver Basha ◽  
K. Mani Govindaraju ◽  
Dhanraj Gopi ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Corrosion Protection ◽  
Glycidyl Methacrylate ◽  
Electrochemical Impedance ◽  
Thermo Gravimetric Analysis ◽  
Gel Permeation Chromatography ◽  
Gravimetric Analysis ◽  
Scanning Calorimetry ◽  
Protection Efficiency ◽  
Ft Ir

Abstract The synthesis of copolymers from different feed ratios of N-(p-bromophenyl)-2- methacrylamide (PBPMA) and glycidyl methacrylate (GMA) was achieved by using free radical solution polymerization technique and characterized using FT-IR, 1H and 13C NMR spectroscopy. The thermal stability of the synthesized copolymers was studied using thermo-gravimetric analysis (TGA) and differential scanning calorimetry (DSC). The molecular weight of the copolymer is determined by gel permeation chromatography (GPC). The corrosion performances of low nickel stainless steel specimens dip coated with different composition of copolymers were investigated in 0.5 M H2SO4 using potentiodynamic polarization and electrochemical impedance spectroscopic (EIS) techniques. The polarization and impedance measurements showed different corrosion protection efficiency with change in composition of the copolymers. It was found that the corrosion protection properties are owing to the barrier effect of the polymer layer covered on the low nickel stainless steel surfaces. However, it is observed that the mole ratio of PBPMA and GMA plays a major role in the protective nature of the copolymer.

scholarly journals Synthesis and Characterization of a Multifunctional Conjugated Polymer

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Emerson C. G. Campos ◽  
Cristiano Zanlorenzi ◽  
Bruno F. Nowacki ◽  
Gabriela M. Miranda ◽  
Denis A. Turchetti ◽  
...  
Keyword(s):  
Conjugated Polymer ◽  
Molar Mass ◽  
Photophysical Properties ◽  
Gel Permeation Chromatography ◽  
Thermal Characterization ◽  
Polymer Structure ◽  
Synthesis And Characterization ◽  
Metallic Ions ◽  
Scanning Calorimetry

This work reports the synthesis and characterization of a conjugated polymer based on fluorene and terpyridine, namely, poly[(9,9-bis(3-((S)-2-methylbutylpropanoate))fluorene-alt-6,6′-(2,2′:6′,2′′-terpyridin-6-yl)] (LaPPS71). The structure was characterized by 1H and 13C nuclear magnetic resonance (NMR) and Fourier-transform infrared (FTIR) spectroscopy. The molar mass was measured by gel permeation chromatography (GPC). As thermal characterization, the glass transition temperature (Tg) was measured by differential scanning calorimetry (DSC). The polymer structure contains two sites capable of complexation with metallic ions, affording the possibility of obtainment of independent or electronically coupled properties, depending on the complexation site. The photophysical properties were fully explored in solution and solid state, presenting ideal results for the preparation of various metallopolymers, in addition to potential application as a metamaterial, due to the presence of the chiral center in the side chains of the polymer.

scholarly journals An investigation on the optical properties of regioregular Poly(3-Hexylthiophene)

2014 ◽  
Vol 17 (2) ◽  
pp. 86-92
Author(s):  
Lam Le ◽  
Tuan Anh Luu
Keyword(s):  
Optical Properties ◽  
Optical Sensors ◽  
Field Effect Transistors ◽  
Gel Permeation Chromatography ◽  
Semiconducting Polymers ◽  
Organic Field Effect Transistors ◽  
Thermal Stabilities ◽  
Smart Windows ◽  
Regioregular Poly ◽  
Ft Ir

Among semiconducting polymers, poly(3-alkylthiophene)s have attracted great attention and generated many studies over the past few years. Among them, regioregular (head-to-tail) poly(3-hexylthiophene) (P3HT) has been especially investigated due to its superior opto-electronic properties, good solubility in the most common organic solvents, chemical and thermal stabilities and also very low toxicity. These properties enable P3HT to be significantly useful in a large variety of applications such as optical sensors, smart windows, organic field effect transistors (OFETs), electrochromic devices, and solar cells. Here, we report the synthesis of poly(3-hexylthiophene) (P3HT) and investigate the optical properties of P3HT in different solvents such as chloroform, tetrahydrofuran, toluene, ethylacetate. The structures of P3HT were confirmed by nuclear magnetic resonance (1H NMR), gel permeation chromatography (GPC), Fourier transform infrared (FT-IR).

scholarly journals Preparations of Poly(lactic acid) Dispersions in Water for Coating Applications

Polymers ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2767
Author(s):  
Giada Belletti ◽  
Sara Buoso ◽  
Lucia Ricci ◽  
Alejandro Guillem-Ortiz ◽  
Alejandro Aragón-Gutiérrez ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Gel Permeation Chromatography ◽  
Sem Analysis ◽  
Water Phase ◽  
Poly Lactic Acid ◽  
Water Emulsion ◽  
Preparation Conditions ◽  
Ft Ir ◽  
Homogenization Methods ◽  
Oil In Water Emulsion

A green, effective methodology for the preparation of water-based dispersions of poly(lactic acid) (PLA) for coating purposes is herein presented. The procedure consists of two steps: in the first one, an oil-in-water emulsion is obtained by mixing a solution of PLA in ethyl acetate with a water phase containing surfactant and stabilizer. Different homogenization methods as well as oil/water phase ratio, surfactant and stabilizer combinations were screened. In the second step, the quantitative evaporation of the organic provides water dispersions of PLA that are stable, at least, over several weeks at room temperature or at 4 °C. Particle size was in the 200–500 nm range, depending on the preparation conditions, as confirmed by scanning electron microscope (SEM) analysis. PLA was found not to suffer significant molecular weight degradation by gel permeation chromatography (GPC) analysis. Furthermore, two selected formulations with glass transition temperature (Tg) of 51 °C and 34 °C were tested for the preparation of PLA films by drying in PTFE capsules. In both cases, continuous films that are homogeneous by Fourier-transform infrared spectroscopy (FT-IR) and SEM observation were obtained only when drying was performed above 60 °C. The formulation with lower Tg results in films which are more flexible and transparent.

scholarly journals Effect of PEEK degradation on commingled fabrics consolidation

2021 ◽  
Author(s):  
Lisa Feuillerat ◽  
Olivier De Almeida ◽  
Jean-Charles Fontanier ◽  
Fabrice Schmidt
Keyword(s):  
Melt Spinning ◽  
Molar Mass ◽  
Degradation Kinetics ◽  
Gel Permeation Chromatography ◽  
Raw Material ◽  
High Porosity ◽  
Absorption Bands ◽  
Mass Distributions ◽  
Key Factor ◽  
Lower Molar

The effects of PEEK degradation on consolidation of commingled semi-finished products have been investigated. Two commingled semi-finished products provided by two different suppliers have been studied and compared to a powdered fabric based on the same PEEK grade. Both were manufactured from aligned AS4 carbon and PEEK yarns but the first product referred as the NCF1 has a lower commingling level than the second one identified as the NCF2. Contrary to what could be expected, under the same processing conditions, consolidation of the NCF1 and the NCF2 systematically results in a high porosity content, above 10%. Fourier Transform Infrared spectrophotometry (FTIR) in ATR mode and Gel Permeation Chromatography (GPC) have shown small molecular structure modifications of PEEK yarns compared to the raw material, such as a shift of molar mass distributions towards lower molar mass and the appearance of C-H absorption bands attributed to non-aromatic alkanes. These modifications have been attributed to sizing of PEEK filament. Calorimetric (DSC) and rheological analyses have demonstrated that the presence of sizing in the semi-finished products have huge consequences on the degradation kinetics. The crystallization temperature decreases and the viscosity increases significantly. This acceleration of the degradation kinetics is the reason of the poor consolidation behavior during composite manufacturing. The conditions of melt spinning extrusion under which the neat PEEK is transformed into filament are therefore a key factor of PEEK degradation.

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