High-Throughput Synthesis of Oligo(ε-caprolactone) / Oligotetrahydrofuran Based Polyurethanes

MRS Advances ◽  
2018 ◽  
Vol 3 (49) ◽  
pp. 2965-2973
Author(s):  
M. Balk ◽  
A. Lendlein ◽  
M. Behl
Keyword(s):  
Molecular Weight ◽  
Chain Length ◽  
High Throughput ◽  
Melting Transition ◽  
Multiblock Copolymers ◽  
Molecular Weights ◽  
Melting Temperatures ◽  
End Groups ◽  
Model Components ◽  
End Group

ABSTRACTRobot assisted synthesis as part of high-throughput (HT) technology can assist in the creation of polymer libraries, e.g. polymers with a variety of molecular weights, by automatizing similar reactions. Especially for multiblock copolymers like polyurethanes (PUs) synthesized from telechels via polyaddition reaction, the adjustment of equivalent molar amounts of reactants requires a comprehensive investigation of end group functionality.In this work, PUs based on oligo(ε-caprolactone) (OCL) / oligotetrahydrofuran (OTHF) as model components were designed utilizing HT synthesis enabling the quantitative determination of the optimized ratio between reactive end-groups via fully automated syntheses without major characterization effort of end group functionality. The semi-crystalline oligomeric telechelics were connected with a diisocyanate and OCL with a molecular weight of 2, 4, or 8 kg∙mol-1 was integrated. Here, optimized molecular weights between 90 ± 10 kg∙mol-1 (in case of OCL 8 kg∙mol-1) and 260 ± 30 kg∙mol-1 (in case of OCL 2 kg∙mol-1) were obtained with an isocyanate content of 120 mol%, whereby 100 mol% of isocyanate groups resulted only in molecular weights between 60 ± 6 kg∙mol-1 (OCL 8 kg∙mol-1) and 80 ± 10 kg∙mol-1 (OCL 2 kg∙mol-1). In addition to the optimized ratio between isocyanate and hydroxy end groups, quantitative influences of the OCL chain length and overall molecular weights of PUs on thermal and mechanical properties were detected. The melting temperatures (Tms) of OCL and OTHF domains were well separated for PUs of low molecular weight, the temperature interval between the Tms decreased when the molecular weight of the PUs was increased, and were even overlapping towards one broad Tm, when OCL 2 kg∙mol-1 was incorporated. The storage modulus E’ was highly dependent on OCL chain length exhibiting an increase with increasing molecular weight of OCL from 220 MPa to 440 MPa at 0 °C and decreased with increasing chain length of PUs. The elongation at break (εb) was analyzed below and above Tm of OTHF resulting in εb = 780-870% at 0 °C and εb = 510-830% at 30 °C for PUs of high molecular weight. Accordingly, stretchability of PUs was almost independent of the state of OTHF (semi crystalline or amorphous) but correlated with the OCL precursor chain length (increasing εb with increasing chain length) and overall molecular weight of PUs (PUs at higher molecular weight exhibited higher εb). Hence, the analysis of these quantitative influences between macromolecular structure of multiblock copolymers and the resulting properties (well separated Tms versus overlapping melting transition, improvement of stretchability) would enable the design of new tailored PUs.

scholarly journals Development of an Optimized MALDI-TOF-MS Method for High-Throughput Identification of High-Molecular-Weight Glutenin Subunits in Wheat

Molecules ◽  
2020 ◽  
Vol 25 (18) ◽  
pp. 4347
Author(s):  
You-Ran Jang ◽  
Kyoungwon Cho ◽  
Se Won Kim ◽  
Susan B. Altenbach ◽  
Sun-Hyung Lim ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
High Throughput ◽  
Glutenin Subunits ◽  
Maldi Tof Ms ◽  
Molecular Weights ◽  
Maldi Tof ◽  
Rp Hplc ◽  
Group 2 ◽  
Tof Ms

Because high-molecular-weight glutenin subunits (HMW-GS) are important contributors to wheat end-use quality, there is a need for high-throughput identification of HMW-GS in wheat genetic resources and breeding lines. We developed an optimized method using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) to distinguish individual HMW-GS by considering the effects of the alkylating reagent in protein extraction, solvent components, dissolving volume, and matrix II components. Using the optimized method, 18 of 22 HMW-GS were successfully identified in standard wheat cultivars by differences in molecular weights or by their associations with other tightly linked subunits. Interestingly, 1Bx7 subunits were divided into 1Bx7 group 1 and 1Bx7 group 2 proteins with molecular weights of about 82,400 and 83,000 Da, respectively. Cultivars containing the 1Bx7 group 2 proteins were distinguished from those containing 1Bx7OE using well-known DNA markers. HMW-GS 1Ax2* and 1Bx6 and 1By8 and 1By8*, which are difficult to distinguish due to very similar molecular weights, were easily identified using RP-HPLC. To validate the method, HMW-GS from 38 Korean wheat varieties previously evaluated by SDS-PAGE combined with RP-HPLC were analyzed by MALDI-TOF-MS. The optimized MALDI-TOF-MS method will be a rapid, high-throughput tool for selecting lines containing desirable HMW-GS for breeding efforts.

Structural studies of oligosilanes produced by catalytic dehydrogenative coupling of primary organosilanes

1987 ◽  
Vol 65 (8) ◽  
pp. 1804-1809 ◽  
Author(s):  
C. Aitken ◽  
J. F. Harrod ◽  
U. S. Gill
Keyword(s):  
Molecular Weight ◽  
Nuclear Magnetic Resonance ◽  
Gel Permeation Chromatography ◽  
Structural Studies ◽  
Molecular Weights ◽  
Molecular Weight Distributions ◽  
Dehydrogenative Coupling ◽  
Weight Distributions ◽  
Gel Permeation ◽  
End Groups

The structures of some poly(organosilylenes), [Formula: see text] (R = Ph, p-tolyl, n-hexyl, and benzyl), produced by catalytic dehydrogenative coupling of primary silanes have been studied by infrared, nuclear magnetic resonance, and mass spectroscopies. These results, combined with data on molecular weights and molecular weight distributions from vapour pressure osmometry and gel permeation chromatography, lead to the conclusion that the polymers are linear and have SiH2R end groups. The polymers all have degrees of polymerization of ca. 10 and very narrow molecular weight dipersions. Some possible features of the mechanism that gives rise to this behaviour are discussed.

THE VISCOSITY – MOLECULAR WEIGHT RELATION FOR POLY-levo-2,3-BUTANEDIYL o-PHTHALATE

1948 ◽  
Vol 26b (12) ◽  
pp. 783-797
Author(s):  
R. W. Watson ◽  
N. H. Grace
Keyword(s):  
Molecular Weight ◽  
High Purity ◽  
Molecular Orientation ◽  
Degree Of Polymerization ◽  
Solution Viscosity ◽  
Dilute Solution ◽  
Molecular Weights ◽  
Complex Relation ◽  
End Group ◽  
Long Chain

The inherent viscosities of dilute solutions of acidic polyesters of high purity have been compared with number average molecular weights accurately determined by end-group titration. For unfractionated resins with a degree of polymerization from 2 to 11 [Formula: see text] the viscosity – molecular weight relation is linear in chloroform at 25 °C. Where [Formula: see text], K = 1.923 × 10−5 and β = 0.0176. For fractionated polyesters from DP 5 to 8, K = 1.959 × 10−6 and β = 0.0161. For unfractionated resins with a DP > 11, molecular weights increase more rapidly than inherent viscosities. Above [Formula: see text] for fractionated resins linearity is resumed, and the slope increases. Several attempts have been made to explain this complex relation. Apparently the short chains remain linear, and the formation of anisotropic fibers at a DP close to 100 establishes a degree of molecular orientation in the long-chain superpolyesters. Isomerization of levo-diol to the diastereoisomer during polycondensation is without effect on the dilute solution viscosity of the resulting resin. Preferential degradation of the longer chains is assumed to be partially responsible for the decreasing slope from DP 11 to 65. As yet it has not been possible to assess the roles played by changes in size distribution, and variation in solvation with increasing chain length, but the data point to a curved viscosity – molecular weight relation in chloroform at 25 °C.

Spreading Characteristics of Molecularly Thin Lubricant on Surfaces With Groove-Shaped Textures: Effects of Molecular Weight and End-Group Functionality

2003 ◽  
Vol 125 (2) ◽  
pp. 350-357 ◽  
Author(s):  
Hedong Zhang ◽  
Yasunaga Mitsuya ◽  
Maiko Yamada
Keyword(s):  
Molecular Weight ◽  
Monte Carlo ◽  
Monte Carlo Method ◽  
Ising Model ◽  
Monte Carlo Simulations ◽  
Simulation Method ◽  
Solid Surfaces ◽  
The Monte Carlo Method ◽  
End Groups ◽  
End Group

Effects of molecular weight and end-group functionality on spreading of molecularly thin perfluoropolyether (PFPE) film over solid surfaces with groove-shaped textures have been studied by experiments and Monte Carlo simulations. In the experiments, lubricant spreading on a surface with groove-shaped textures was measured by making use of the phenomenon in which diffracted light weakens in the lubricant-covered region. It is found that grooves serve to accelerate spreading and this effect increases for deeper grooves, and also the accelerating rate becomes larger for a lubricant having a larger molecular weight or functional end-groups. In the simulations, the Monte Carlo method based on the Ising model was extended to enable us to evaluate the effect of molecular weight on the spreading of non-functional lubricant inside a groove. The validity of the newly developed simulation method was well confirmed from the agreement between the simulation and experimental results.

Influence of Thermal Treatment on the Molecular Weights of Polyhydroxyalkanoate Containing 3-Hydroxyhexanoate

2013 ◽  
Vol 812 ◽  
pp. 250-253 ◽  
Author(s):  
Yoga Sugama Salim ◽  
Chin Han Chan ◽  
Kumar Sudesh ◽  
Seng Neon Gan
Keyword(s):  
Molecular Weight ◽  
Thermal Treatment ◽  
Gel Permeation Chromatography ◽  
Polymer Processing ◽  
Polymer Chains ◽  
Molecular Weights ◽  
Gel Permeation ◽  
Ftir Spectrometer ◽  
Major Reduction ◽  
End Group

With blooming interests in the research of biodegradable polyesters produced from microorganisms as well as polymer processing and technology, this study is intended to reveal the influence of thermal treatment on the molecular weight of poly (3-hydroxybutyrate-co-3 mol% 3-hydroxyhexanoate)/P(3HB-co-3 mol% 3HHx), a copolymer of polyhydroxyalkanoates (PHA). P(3HB-co-3 mol% 3HHx) was thermally treated using Differential Scanning Calorimeter and analyzed using Gel Permeation Chromatography and Attenuated Total Reflectance-Fourier transform infrared (ATR-FTIR) spectrometer. Results from gel permeation chromatography suggest a major reduction of molecular weight up to 50 % when P(3HB-co-3 mol% 3HHx) is exposed to 180 °C for 30 mins. The half-time degradation of P(3HB-co-3 mol% 3HHx) treated at 170 °C and 180 °C is 14.1 and 9.9 mins, respectively. FTIR spectroscopy shows an increase absorbance intensity of P(3HB-co-3 mol% 3HHx) after thermal treatment, indicating a formation of more alkenyl and carboxylic end-group in polymer chains due to random chain scissions.

scholarly journals Intrinsic Viscosity-molecular Weight Relationship of Poly (Hexanediol Adipate)

2019 ◽  
pp. 1-8
Author(s):  
Jiankun Li ◽  
Zegang Zong ◽  
Dehua Hou ◽  
Bojun Tu ◽  
Weilan Xue ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Intrinsic Viscosity ◽  
Average Molecular Weight ◽  
Group Analysis ◽  
Gel Permeation Chromatography ◽  
Molecular Weights ◽  
The One ◽  
Relationship Of ◽  
The Relationship ◽  
End Group

In this work, a series of poly(Hexanediol adipate)(PHA) samples (103＜Mn＜104) with narrow molecular weight distribution were prepared by the polymerization between adilic acid and 1,6-hexandiol. End-group analysis was applied to determine the number average molecular weight (Mn) of PHA. Gel permeation chromatography (GPC) was employed to obtain the average molecular weights (Mn, Mv, Mw).The intrinsic viscosity of the samples in the tetrahydrofuran (THF) solution was determined at 298 K by the dilution extrapolation method and the one-point method. The relationship between the intrinsic viscosity and the molecular weight for PHA was studied by the Mark-Houwink-Sakurada (MHS) equation, and the parameters of equation were determined.

scholarly journals The Enzymatic Phosphorylation of Nucleic Acids and Its Application to End-Group Analysis

1966 ◽  
Vol 49 (6) ◽  
pp. 81-97 ◽  
Author(s):  
Charles C. Richardson ◽  
Bernard Weiss
Keyword(s):  
Molecular Weight ◽  
Group Analysis ◽  
Single Strand ◽  
Selective Labeling ◽  
Phosphodiester Bond ◽  
Polynucleotide Kinase ◽  
End Groups ◽  
Hydroxyl Termini ◽  
End Group

Polynucleotide kinase catalyzes the transfer of a phosphate group from ATP to the 5'-hydroxyl termini of polynucleotides. Selective labeling of the 5'-hydroxyl termini of DNA with polynucleotide kinase has been used to study the number and the identity of the 5'-terminal residues of bacteriophage DNA's, and to examine the nature of the phosphodiester bond cleavages produced by endonucleases and by sonic irradiation. The intact strands of T7 DNA bear 5'-phosphoryl end-groups; only deoxyadenylate and deoxythymidylate are present as 5'-terminal residues. The intact strands of native λ-DNA bear 5'-hydroxyl end-groups. M13 DNA, a circular molecule, cannot be phosphorylated. End-group labeling of DNA provides a method for determination of molecular weight; calibration against other DNA preparations is not required. The molecular weight of a single strand of T7 DNA, determined by end-group labeling, is 13.1 x 106; the molecular weight of a single strand of λ-DNA is 16.0 x 106. These values are in agreement with molecular weight estimates by sedimentation analysis and electron microscopy. Sonic irradiation of DNA has been shown to favor the production of polynucleotides terminated by 5'-phosphomonoester groups. All four deoxyribonucleotides are present as 5'-terminal residues of sonicated DNA.

Polyethylene glycol oligomers as siloxane modificators in consolidation of carbonate stones

2016 ◽  
Vol 88 (12) ◽  
pp. 1117-1128 ◽  
Author(s):  
Bruno Sena da Fonseca ◽  
Susana Piçarra ◽  
Ana Paula Ferreira Pinto ◽  
Maria de Fátima Montemor
Keyword(s):  
Molecular Weight ◽  
Polyethylene Glycol ◽  
Carboxylic Acid ◽  
Sol Gel ◽  
Silica Matrix ◽  
Strength Increase ◽  
Molecular Weights ◽  
Uniform Strength ◽  
End Groups ◽  
Stone Consolidants

AbstractThe overall performance of alkoxysilanes as stone consolidants is constrained by stone mineralogy (particularly in the carbonate varieties) and by their tendency to crack during drying. In an attempt to overcome these problems, polyethylene glycol “chains” with two carboxylic acid end-groups (PEG-CA) were introduced in siloxane sols obtained by sol-gel chemistry using tetraethoxysilane (TEOS) as precursor. Different pre-condensation degrees (by varying the stirring times of sol-gel reaction: 10 min, 2, and 24 h) and PEG-CA chains with different molecular weights were studied as variables affecting the initial efficacy of the consolidants when applied into a limestone. The sol containing siloxanes with the lowest pre-condensation degree (10 min stirring) was quite susceptible to the carbonate media and thus a poor consolidation was achieved. The sol with the highest pre-condensation degree (24 h stirring) together with the PEG-CA chains with intermediate molecular weight produced significant and uniform strength gains along the stone depth. The consolidation also showed to be highly dependent on the molecular weight of the PEG-CA chains, the PEG-CA with highest molecular weight produced a non-uniform strength increase with potential harmful side effects. The results confirmed the role of carboxylic acid end-groups as efficient sol-gel catalysts and their ability to be incorporated into the silica matrix in the presence of carbonate stone.

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