Selective or living organopolymerization of a six-five bicyclic lactone to produce fully recyclable polyesters

2019 ◽  
Vol 10 (23) ◽  
pp. 3097-3106 ◽  
Author(s):  
Robin M. Cywar ◽  
Jian-Bo Zhu ◽  
Eugene Y.-X. Chen
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Room Temperature ◽  
Heterocyclic Carbenes ◽  
Base Pairs ◽  
Ring Open ◽  
Bicyclic Lactone

A ring-fused γ-butyrolactone can be selectively ring-open polymerized at room temperature by N-heterocyclic carbenes to cyclic polyester or by bifunctional (thio)urea and base pairs in a living fashion to high molecular weight linear polyester that can be organocatalytically and quantitatively recycled at 120 °C.

Formation of high-molecular weight polyaminoborane by Fe hydride catalysed dehydrocoupling of methylamine borane

2017 ◽  
Vol 46 (21) ◽  
pp. 6843-6847 ◽  
Author(s):  
F. Anke ◽  
D. Han ◽  
M. Klahn ◽  
A. Spannenberg ◽  
T. Beweries
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Room Temperature ◽  
Catalyst Precursor

The complex [(PNHP)Fe(H)(CO)(HBH3)] (PNHP = HN(CH2CH2Pi-Pr2)2) serves as a catalyst precursor for the selective dehydrocoupling of methylamine borane at room temperature, tentatively via an off-metal polymerisation pathway.

Gel Entrapment of Antibody: A New Strategy for Facilitating Both Manual and Automated Radioimmunoassay

1973 ◽  
Vol 19 (12) ◽  
pp. 1339-1344 ◽  
Author(s):  
Stuart J Updike ◽  
John D Simmons ◽  
Douglas H Grant ◽  
Judith A Magnuson ◽  
Theodore L Goodfriend
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Room Temperature ◽  
Solid Phase ◽  
Binding Activity ◽  
Angiotensin I ◽  
Chromatographic Columns ◽  
New Strategy ◽  
Sample Application ◽  
Solid Phase Binding

Abstract A technique of radioimmunoassay is presented that eliminates pipetting and centrifugation, and excludes interferences by high-molecular-weight materials from the incubation and separation steps. A solid-phase binding reagent is prepared by first entrapping antibody in polyacrylamide gel. This gel is then fragmented, sieved, dried with ethanol or lyophilized, and placed in miniature disposable chromatographic columns. Application of the sample to the intra-gel column compartment is determined by the water regain of the gel. This pipetless method of sample application depends on reproducible aliquots of dry gel particles in every column. A method for preloading radiolabeled hormone and standard hormone into the column is also described. This technique has been successfully applied to the assay of angiotensin I and insulin. Dry antibody—gel stored at room temperature for 26 months has not shown loss of binding activity.

scholarly journals Ring-opening polymerization of cyclohexene oxide using aluminum amine–phenolate complexes

2015 ◽  
Vol 44 (27) ◽  
pp. 12098-12102 ◽  
Author(s):  
Hart Plommer ◽  
Immanuel Reim ◽  
Francesca M. Kerton
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Ring Opening ◽  
Ring Opening Polymerization ◽  
Cyclohexene Oxide ◽  
Ring Open

Al(iii) catalysts at concentrations as low as 0.001% ring-open cyclohexene oxide to yield high molecular weight polyether with narrow dispersity.

scholarly journals Convenient preparation of high molecular weight poly(dimethylsiloxane) using thermally latent NHC-catalysis: a structure-activity correlation

2015 ◽  
Vol 11 ◽  
pp. 2261-2266 ◽  
Author(s):  
Stefan Naumann ◽  
Johannes Klein ◽  
Dongren Wang ◽  
Michael R Buchmeiser
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Anionic Polymerization ◽  
Heterocyclic Carbenes ◽  
Structure Activity ◽  
Convenient Preparation ◽  
High Molecular Weight Poly

The polymerization of octamethylcyclotetrasiloxane (D4) is investigated using several five-, six- and seven-membered N-heterocyclic carbenes (NHCs). The catalysts are delivered in situ from thermally susceptible CO2 adducts. It is demonstrated that the polymerization can be triggered from a latent state by mild heating, using the highly nucleophilic 1,3,4,5-tetramethylimidazol-2-ylidene as organocatalyst. This way, high molecular weight PDMS is prepared (up to >400 000 g/mol, 1.6 < Ð M < 2.5) in yields >95%, using low catalyst loadings (0.2–0.1 mol %). Furthermore, the results suggest that a nucleophilic, zwitterionic mechanism is in operation, in preference to purely anionic polymerization.

scholarly journals Dextranol: A better lyoprotectant

2018 ◽  
Author(s):  
Bryan Joshua Jones ◽  
Advitiya Mahajan ◽  
Alptekin Aksan
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Serum Proteins ◽  
Specific Antigen ◽  
Clinical Samples ◽  
Serum Samples ◽  
Protein Molecules ◽  
Anomeric Carbon

Dextranol, a reduced dextran, prevents damage to stored dry protein samples that unmodified dextran would otherwise cause. Lyoprotectants like the polysaccharide dextran are critical for preserving dried protein samples by forming rigid a glass that protects entrapped protein molecules. Stably dried proteins are important for maintaining critical information in clinical samples like blood serum. However, we found that dextran reacts with serum proteins during storage, producing high-molecular weight Amadori-product conjugates. These conjugates appeared in a matter of days or weeks when stored at elevated temperatures (37° or 45°C), but also appeared on a timescale of months when stored at room temperature. We synthesized a less reactive dextranol by reducing dextran’s anomeric carbon from an aldehyde to an alcohol. Serum samples dried in a dextranol-based matrix protected the serum proteins from forming high-molecular weight conjugates. The levels of four cancer-related serum biomarkers (prostate specific antigen, neuropiln-1, osteopontin, and metalloproteinase 7) decreased, as measured by immunoassay, when serum samples were stored for one to two weeks in dextran-based matrix. Switching to a dextran-based lyoprotection matrix slightly reduced the damage to osteopontin and completely stopped any detectable damage during storage in the other three biomarkers when for a period of two weeks at 45°C. Dextranol offers a small and easy modification to dextran that significantly improves the molecule’s function as a lyoprotectant by eliminating the potential for damaging protein-polysacharide conjugation.

scholarly journals High-Yield Grafting of Carboxylated Polymers to Wood Pulp Fibers

2021 ◽  
Author(s):  
Hongfeng Zhang ◽  
Paul Bicho ◽  
Erin A.S. Doherty ◽  
Richard J. Riehle ◽  
Jose Moran Mirabal ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Room Temperature ◽  
High Yield ◽  
Chemical Fixation ◽  
Pulp Fibers ◽  
Curing Conditions ◽  
Ph Values ◽  
Primary Mechanism ◽  
Poly Ethylene

Abstract Poly(ethylene-alt-maleic acid), PEMAc, is a linear polymer that, along with its isomer polyacrylic acid, has the highest carboxylic acid content of any polymer. The goal of this work was to elucidate the mechanisms that control the amount of PEMAc that is permanently fixed on pulp fibers after the impregnation of dry pulp with a dilute PEMAc solution followed by drying/heating (curing). Two mechanisms by which PEMAc is fixed to cellulose fibers were discovered, chemical, and physical fixation. With room temperature drying only physical fixation is operative. Evidence supports the explanation that physical fixation is a consequence of the slow swelling and dissolution of thick dried PEMAc deposits on fiber surfaces. Chemical fixation includes grafting to cellulose plus enhanced cohesion within thick PEMAc layers, possibly due to interchain crosslinking. The pH of the PEMAc impregnation solution determines the fixation mechanism for curing temperatures above 100 o C. Physical fixation dominates when pH > 8 whereas chemical fixation dominates for impregnation pH values < 7, suggesting the curing reactions require partial or complete protonation of the succinic acid moieties. The yield of impregnated polymer fixed to the fibers after washing depends upon the fixation mechanism. When chemical fixation dominates, the yields for low and high molecular weight PEMAc doses less than 0.1 meq/g (6.3 kg PEMA/tonne dry pulp) were close to or equaled 100%. By contrast, when the primary mechanism is physical fixation, yields are ~50% for high molecular weight PEMAc and 0-20% for low MW PEMAc. These results show that high PEMAc fixation yields can be achieved under curing conditions that could be implemented in pulp drying machines producing dry market pulp.

Polyamide 6 and high molecular weight phenol novolac blend having excellent mechanical properties in humid conditions

2018 ◽  
Vol 32 (6) ◽  
pp. 778-794 ◽  
Author(s):  
Takayuki Hirai ◽  
Kenzo Fukumori ◽  
Taiji Ikawa ◽  
Tetsuya Oda
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Glass Transition ◽  
High Molecular Weight ◽  
Room Temperature ◽  
Glassy State ◽  
Physical And Mechanical Properties ◽  
Polyamide 6 ◽  
Low Molecular Weight ◽  
Melt Mixing

Polymer blends of polyamide 6 (PA6) and phenol novolac (PN) were prepared by melt mixing. Up to 30 wt% of high molecular weight PN (HPN) or low molecular weight PN (LPN) was blended with PA6, and the physical and mechanical properties were examined. The water absorption of PA6 is inhibited by PN, and this effect is independent of the molecular weight of PN. PA6 and PN are miscible, and their blends show a single glass transition temperature ( T g) that is higher than that of PA6. HPN can enhance the T g of PA6 more efficiently than LPN because of its high T g. PA6 and the PA6/LPN blend after immersion in water had lower-than-room-temperature T gs transitioning to rubbery states. In contrast, the PA6/HPN blend after immersion in water had a higher-than-room-temperature T g. The PA6/HPN blend in water has excellent mechanical properties in its glassy state compared to those of PA6 in the dry state. Thus, the PA6/HPN blend can be used to broaden the applications of PA6, especially in humid conditions.

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