scholarly journals cis-1,4 Selective Coordination Polymerization of 1,3-Butadiene and Copolymerization with Polar 2-(4-Methoxyphenyl)-1,3-butadiene by Acenaphthene-Based α-Diimine Cobalt Complexes Featuring Intra-Ligand π-π Stacking Interactions

Polymers ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 3329
Author(s):  
Beibei Wang ◽  
Heng Liu ◽  
Tao Tang ◽  
Xuequan Zhang
Keyword(s):  
Molecular Weight ◽  
Cobalt Complexes ◽  
Stacking Interactions ◽  
Water Contact ◽  
Coordination Polymerization ◽  
Molecular Weights ◽  
Angle Measurements ◽  
Π Stacking ◽  
High Yields ◽  
Polar Monomer

Highly cis-1,4 selective (up to 98%) coordination–insertion polymerization of 1,3-butadiene (BD) has been achieved herein using acenaphthene-based α-diimine cobalt complexes. Due to the presence of intra-ligand π-π stacking interactions, the complexes revealed high thermostability, affording polybutadiene products in high yields. Moreover, all of the obtained polymers possessed a relatively narrow molecular weight distribution as well as high molecular weight (up to 92.2 × 104 Dalton). The molecular weights of the resultant polybutadienes could be finely tuned by varying polymerization parameters, including temperature, Al/Co ratio, etc. Moreover, the copolymerization of butadiene with polar monomer 2-(4-methoxyphenyl)-1,3-butadiene (2-MOPB) was also successfully realized to produce a type of polar cis-1,4 polybutadiene (cis-1,4 content: up to 98.1%) with a range of 2-MOPB content (0.46–1.83%). Water contact angle measurements indicated that the insertion of a polar monomer into a polymer chain could significantly improve the polymer’s surface property.

scholarly journals Synthesis of Hydrophilic Poly(butylene succinate-butylene dilinoleate) (PBS-DLS) Copolymers Containing Poly(ethylene glycol) (PEG) of Variable Molecular Weights

Polymers ◽  
2021 ◽  
Vol 13 (18) ◽  
pp. 3177
Author(s):  
Moein Zarei ◽  
Miroslawa El Fray
Keyword(s):  
Molecular Weight ◽  
Thermal Properties ◽  
Ethylene Glycol ◽  
Polymeric Materials ◽  
Glycol Succinate ◽  
Resonance Spectroscopy ◽  
Scanning Calorimetry ◽  
Water Contact ◽  
Butylene Succinate ◽  
Molecular Weights

Polymeric materials have numerous applications from the industrial to medical fields because of their vast controllable properties. In this study, we aimed to synthesize series of poly(butylene succinate-dilinoleic succinate-ethylene glycol succinate) (PBS-DLS-PEG) copolymers, by two-step polycondensation using a heterogeneous catalyst and a two-step process. PEG of different molecular weights, namely, 1000 g/mol and 6000 g/mol, was used in order to study its effect on the surface and thermal properties. The amount of the PBS hard segment in all copolymers was fixed at 70 wt%, while different ratios between the soft segments (DLS and PEG) were applied. The chemical structure of PBS-DLS-PEG was evaluated using Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. Gel permeation chromatography was used to determine the molecular weight and dispersity index. The results of structural analysis indicate the incorporation of PEG in the macrochain. The physical and thermal properties of the newly synthesized copolymers were also evaluated using water contact angle measurements, differential scanning calorimetry and dynamic thermomechanical analysis. It was found that increasing the amount of PEG of a higher molecular weight increased the surface wettability of the new materials while maintaining their thermal properties. Importantly, the two-step melt polycondensation allowed a direct fabrication of a polymeric filament with a well-controlled diameter directly from the reactor. The obtained results clearly show that the use of two-step polycondensation in the melt allows obtaining novel PBS-DLS-PEG copolymers and creates new opportunities for the controlled processing of these hydrophilic and thermally stable copolymers for 3D printing technology, which is increasingly used in medical techniques.

scholarly journals Enzyme-Assisted Fucoidan Extraction from Brown Macroalgae Fucus distichus subsp. evanescens and Saccharina latissima

Marine Drugs ◽  
2020 ◽  
Vol 18 (6) ◽  
pp. 296 ◽  
Author(s):  
Thuan Thi Nguyen ◽  
Maria Dalgaard Mikkelsen ◽  
Vy Ha Nguyen Tran ◽  
Vo Thi Dieu Trang ◽  
Nanna Rhein-Knudsen ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Alginate Lyase ◽  
Saccharina Latissima ◽  
Brown Macroalgae ◽  
Brown Seaweeds ◽  
Molecular Weights ◽  
Fucus Distichus ◽  
Assisted Extraction ◽  
High Yields ◽  
Enzyme Assisted Extraction

Fucoidans from brown macroalgae (brown seaweeds) have different structures and many interesting bioactivities. Fucoidans are classically extracted from brown seaweeds by hot acidic extraction. Here, we report a new targeted enzyme-assisted methodology for fucoidan extraction from brown seaweeds. This enzyme-assisted extraction protocol involves a one-step combined use of a commercial cellulase preparation (Cellic®CTec2) and an alginate lyase from Sphingomonas sp. (SALy), reaction at pH 6.0, 40 °C, removal of non-fucoidan polysaccharides by Ca2+ precipitation, and ethanol-precipitation of crude fucoidan. The workability of this method is demonstrated for fucoidan extraction from Fucus distichus subsp. evanescens (basionym Fucus evanescens) and Saccharina latissima as compared with mild acidic extraction. The crude fucoidans resulting directly from the enzyme-assisted method contained considerable amounts of low molecular weight alginate, but this residual alginate was effectively removed by an additional ion-exchange chromatographic step to yield pure fucoidans (as confirmed by 1H NMR). The fucoidan yields that were obtained by the enzymatic method were comparable to the chemically extracted yields for both F. evanescens and S. latissima, but the molecular sizes of the fucoidans were significantly larger with enzyme-assisted extraction. The molecular weight distribution of the fucoidan fractions was 400 to 800 kDa for F. evanescens and 300 to 800 kDa for S. latissima, whereas the molecular weights of the corresponding chemically extracted fucoidans from these seaweeds were 10–100 kDa and 50–100 kDa, respectively. Enzyme-assisted extraction represents a new gentle strategy for fucoidan extraction and it provides new opportunities for obtaining high yields of native fucoidan structures from brown macroalgae.

scholarly journals Structure and Properties of PSf Hollow Fiber Membranes with Different Molecular Weight Hyperbranched Polyester Using Pentaerythritol as Core

Polymers ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 383
Author(s):  
Min Liu ◽  
Long-Bao Zhao ◽  
Li-Yun Yu ◽  
Yong-Ming Wei ◽  
Zhen-Liang Xu
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Hollow Fiber ◽  
Pure Water ◽  
Esterification Reaction ◽  
Hollow Fiber Membranes ◽  
Water Contact ◽  
Molecular Weights ◽  
Hyperbranched Polyesters ◽  
Fiber Membranes

A homologous series of hyperbranched polyesters (HBPEs) was successfully synthesized via an esterification reaction of 2,2-bis(methylol)propionic acid (bis-MPA) with pentaerythritol. The molecular weights of the HBPEs were 2160, 2660, 4150 and 5840 g/mol, respectively. These HBPEs were used as additives to prepare polysulfone (PSf) hollow fiber membranes via non-solvent induced phase separation. The characteristic behaviors of the casting solution were investigated, as well as the morphologies, hydrophilicity and mechanical properties of the PSf membranes. The results showed that the initial viscosities of the casting solutions were increased, and the shear-thinning phenomenon became increasingly obvious. The demixing rate first increased and then decreased when increasing the HBPE molecular weight, and the turning point was 2660 g/mol. The PSf hollow fiber membranes with different molecular weights of HBPEs had a co-existing morphology of double finger-like and sponge-like structures. The starting pure water contact angle decreased obviously, and the mechanical properties improved.

Synthesis of α,ω-bis(3-aminopropyldiethoxylsilane) Poly(tri fluoropropylmethyl)siloxanes

e-Polymers ◽  
2007 ◽  
Vol 7 (1) ◽  
Author(s):  
Zhendong Shi ◽  
Xinling Wang
Keyword(s):  
Molecular Weight ◽  
Ring Opening ◽  
Reaction Rate ◽  
Ring Opening Polymerization ◽  
Step Process ◽  
Molecular Weights ◽  
H Nmr ◽  
One Step ◽  
Ft Ir ◽  
High Yields

AbstractHigh molecular weight α,ω-bis(3-aminopropyldiethoxylsilane) poly(tri fluoropropylmethyl)siloxanes (APTFPMS) were prepared via a “one-step” process, based on the ring-opening polymerization of 1,3,5-tris(trifluoropropylmethyl) cyclotrisiloxane (F3) in the presence of water and 3-aminopropyltriethoxysilane (APTES). GPC, FT-IR and 1H NMR confirmed the structure of the polymers. It was found that the amount of APTES had significant influence on the reaction rate and the molecular weights of polymers decreased with the increasing amount of water. It was probably because both water and the amino group of APTES favoured generation of hydroxyl ions, which efficiently initiate the polymerization of F3 to achieve APTFPMS. In order to verify this mechanism, another “two-step” process was also performed: Firstly the α,ω-dihydroxylated poly(trifluoropropylmethyl) siloxanes were synthesized from F3 catalyzed by both diaminoethane and water, then reacted with APTES to achieve APTFPMS. All the syntheses had high yields and the molecular weight of the polymers ranged from 2000 to 25000.

Evidence of Intercolumnar π−π Stacking Interactions in Amino-Acid-Based Low-Molecular-Weight Organogels

Langmuir ◽  
2010 ◽  
Vol 26 (22) ◽  
pp. 16818-16827 ◽  
Author(s):  
Florent Allix ◽  
Pasquale Curcio ◽  
Quoc Nghi Pham ◽  
Guillaume Pickaert ◽  
Brigitte Jamart-Grégoire
Keyword(s):  
Molecular Weight ◽  
Amino Acid ◽  
Low Molecular Weight ◽  
Stacking Interactions ◽  
Π Stacking

Investigation by HPLC of the Catabolism of Recombinant Tissue Plasminogen Activator in the Rat

1988 ◽  
Vol 60 (01) ◽  
pp. 107-112 ◽  
Author(s):  
Roy Harris ◽  
Louis Garcia Frade ◽  
Lesley J Creighton ◽  
Paul S Gascoine ◽  
Maher M Alexandroni ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Plasminogen Activator ◽  
Tissue Plasminogen Activator ◽  
Half Life ◽  
Recombinant Tissue Plasminogen Activator ◽  
Rat Plasma ◽  
High Molecular Weight Complex ◽  
Molecular Weights ◽  
Major Activity ◽  
Tissue Plasminogen

SummaryThe catabolism of recombinant tissue plasminogen activator (rt-PA) was investigated after injection of radiolabelled material into rats. Both Iodogen and Chloramine T iodination procedures yielded similar biological activity loss in the resultant labelled rt-PA and had half lives in the rat circulation of 1 and 3 min respectively. Complex formation of rt-PA was investigated by HPLC gel exclusion (TSK G3000 SW) fractionation of rat plasma samples taken 1-2 min after 125I-rt-PA injection. A series of radiolabelled complexes of varying molecular weights were found. However, 60% of the counts were associated with a single large molecular weight complex (350–500 kDa) which was undetectable by immunologically based assays (ELISA and BIA) and showed only low activity with a functional promoter-type t-PA assay. Two major activity peaks in the HPLC fractions were associated with Tree t-PA and a complex having a molecular weight of ̴ 180 kDa. HPLC fractionation to produce these three peaks at various timed intervals after injection of 125I-rt-PA showed each to have a similar initial rate half life in the rat circulation of 4-5 min. The function of these complexes as yet is unclear but since a high proportion of rt-PA is associated with a high molecular weight complex with a short half life in the rat, we suggest that the formation of this complex may be a mechanism by which t-PA activity is initially regulated and finally cleared from the rat circulation.

Permeability Enhancing and Chemotactic Activities of Lower Molecular Weight Degradation Products of Human Fibrinogen

1981 ◽  
Vol 45 (01) ◽  
pp. 090-094 ◽  
Author(s):  
Katsuo Sueishi ◽  
Shigeru Nanno ◽  
Kenzo Tanaka
Keyword(s):  
Molecular Weight ◽  
Degradation Products ◽  
Electron Microscopic Observation ◽  
Chemotactic Activity ◽  
Lower Molecular Weight ◽  
Electron Microscopic ◽  
Human Fibrinogen ◽  
Rabbit Skin ◽  
Molecular Weights ◽  
Active Fragments

SummaryFibrinogen degradation products were investigated for leukocyte chemotactic activity and for enhancement of vascular permeability. Both activities increased progressively with plasmin digestion of fibrinogen. Active fragments were partially purified from 24 hr-plasmin digests. Molecular weights of the permeability increasing and chemotactic activity fractions were 25,000-15,000 and 25,000 respectively. Both fractions had much higher activities than the fragment X, Y, D or E. Electron microscopic observation of the small blood vessels in rabbit skin correlated increased permeability with the formation of characteristic gaps between adjoining endothelial cells and their contraction.These findings suggest that lower molecular weight degradation products of fibrinogen may be influential in contributing to granulocytic infiltration and enhanced permeability in lesions characterized by deposits of fibrin and/or fibrinogen.

Toxicity of Heparinoids, with Special Reference to the Precipitation of Fibrinogen

1964 ◽  
Vol 12 (01) ◽  
pp. 232-261 ◽  
Author(s):  
S Sasaki ◽  
T Takemoto ◽  
S Oka
Keyword(s):  
Molecular Weight ◽  
Dextran Sulfate ◽  
Anticoagulant Activity ◽  
Molecular Structures ◽  
Severe Reaction ◽  
Clinical Use ◽  
Molecular Weights ◽  
Close Relationship

SummaryTo demonstrate whether the intravascular precipitation of fibrinogen is responsible for the toxicity of heparinoid, the relation between the toxicity of heparinoid in vivo and the precipitation of fibrinogen in vitro was investigated, using dextran sulfate of various molecular weights and various heparinoids.1. There are close relationships between the molecular weight of dextran sulfate, its toxicity, and the quantity of fibrinogen precipitated.2. The close relationship between the toxicity and the precipitation of fibrinogen found for dextran sulfate holds good for other heparinoids regardless of their molecular structures.3. Histological findings suggest strongly that the pathological changes produced with dextran sulfate are caused primarily by the intravascular precipitates with occlusion of the capillaries.From these facts, it is concluded that the precipitates of fibrinogen with heparinoid may be the cause or at least the major cause of the toxicity of heparinoid.4. The most suitable molecular weight of dextran sulfate for clinical use was found to be 5,300 ~ 6,700, from the maximum value of the product (LD50 · Anticoagulant activity). This product (LD50 · Anticoagulant activity) can be employed generally to assess the comparative merits of various heparinoids.5. Clinical use of the dextran sulfate prepared on this basis gave satisfactory results. No severe reaction was observed. However, two delayed reactions, alopecia and thrombocytopenia, were observed. These two reactions seem to come from the cause other than intravascular precipitation.

Molecular Weights of Factor VIII (AHF) and Factor IX (PTC) by Electron Irradiation

1962 ◽  
Vol 08 (02) ◽  
pp. 270-275 ◽  
Author(s):  
David L Aronson ◽  
John W Preiss ◽  
Michael W Mosesson
Keyword(s):  
Molecular Weight ◽  
Factor Viii ◽  
Electron Irradiation ◽  
Factor Ix ◽  
Molecular Weights

SummaryThe molecular weights of AHF (factor VIII) and of PTC (factor IX) have been estimated by their sensitivity to inactivation by 7 kilovolt electrons. The molecular weight of AHF was found to be 180 000 by this method and that of PTC was found to be 110 000.

Nanostructured Polymer Brushes With Reversibly Changing Properties

2002 ◽  
Vol 727 ◽  
Author(s):  
Denys Usov ◽  
Manfred Stamm ◽  
Sergiy Minko ◽  
Christian Froeck ◽  
Andreas Scholl ◽  
...  
Keyword(s):  
Polymer Brushes ◽  
Phase Segregation ◽  
Water Contact ◽  
Angle Measurements ◽  
Nanostructured Polymer ◽  
Contact Angle Measurements ◽  
Vertical Segregation ◽  
Oxygen Plasma Etching ◽  
Grafting From ◽  
Photoemission Electron

AbstractWe investigated the interplay between different mechanisms of the lateral and vertical segregation in the synthesized via “grafting from” approach symmetric A/B (where A and B are poly(styrene-co-2,3,4,5,6-pentafluorostyrene) and poly(methylmethacrylate), respectively) polymer brushes upon exposure to different solvents. We used X-ray photoemission electron spectroscopy and microscopy (X-PEEM), AFM, water contact angle measurements, and oxygen plasma etching to study morphology of the brushes. The ripple morphology after toluene (nonselective solvent) revealed elongated lamellar-like domains of A and B polymers alternating across the surface. The dimple-A morphology consisting of round clusters of the polymer A was observed after acetone (selective solvent for B). The top layer was enriched with the polymer B showing that the brush underwent both the lateral and vertical phase segregation. A qualitative agreement with predictions of SCF theory was found.

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