Mega one million molecular weight macromolecules, is excellent in surface hardness lubricant
With the development of technology, polymer synthesis, polymer having a complex structure and size can now be more easily prepared. For example, by skillfully selecting the monomers and the polymerization conditions, the synthesis of high molecular weight, linear polymers topology has been widely reported, and to give some very interesting properties. However, spherical polymer having a molecular weight of one million in the past to obtain accurate No synthesis, and because its structure is very compact single polymer may be fixed to the nanoscale 3D structures of spherical, they also have the characteristics of not sufficiently It is able to explore. Recently, Professor Mark W. Grinstaff Jayachandran N. Kizhakkedathu from the University of British Columbia, and Boston University reported together the one hyperbranched polyglycerols 3D spherical morphology (molecules), such a polymer can be synthesized, and precisely maintain a high molecular weight. In practical applications, it can reduce the soft, the coefficient of friction between the hard surface, and exhibit similar rheological properties of the fluid lubricant. The study \”Mega macromolecules as single molecule lubricants for hard and soft surfaces\” was published in \”Nature Communications.\”
Preparation and Characterization: Such a two-step Mega macromolecule is prepared by a ring opening reaction. Specifically, by using dry trimethylolpropane as an initiator, and under argon, was added potassium methoxide, do deprotonated. The initiator is then added dry dioxane, was slowly injected into the monomer and glycidol, after 5 hours, to obtain a branched polymer structure of the macro-initiator. This macro-initiator then dried again, and dissolved in DMF agents do deprotonated, followed by repeating the foregoing monomers injection step, after washing, purification, such Mega macromolecules can be prepared. NMR results show that this polymer exhibits polyglycerol backbone, which branching ratio between 53% ~ 57% While the molecular weight of the branched polymers obtained by this method as compared to previously reported is the highest. Synthesis of three different molecular weights Mega macromolecule, respectively Mega HPG-1 (molecular weight Mw 1.3 MDa), Mega HPG-2 (Mw 2.9 MDa), and Mega HPG-3 (Mw 9.3 MDa). Wherein HPG-3 hydroxyl groups on each polymer chain up to 87,000 or more, which makes the properties of the polymer greatly affected and facilitate post-modification. Thus such a polymer is very soluble in water, solubility of up to 380 mg / mL or more. GPC results showed unimodal distribution of such polymers, DLS results showed that the molecular weight of such polymers in MDa 1.3 to 21 nm, in 9.3 MDa to 43 nm. Cryo-SEM micrograph corresponding results presented indicate that this polymer monodisperse spherical particle morphology.
Comparison with other polymer systems indicate that Mega macromolecules such has very low intrinsic viscosity, and the size of the correlation of the molecular weight and its intrinsic viscosity is not. This result is significantly different polyamide dendrimers. Compared with other water soluble polymers such as PEG and the like, which is very low intrinsic viscosity value. Integrated while watching, Mega collection of molecules of the ultra-high molecular weight, compact size, low intrinsic viscosity, and is independent of molecular weight.
Application: Because of this dendrimer having excellent properties such as high solubility , low density and intrinsic viscosity. And because of its unique shape and a single spherical particles, the authors speculate that the rheological properties may be different. For its lubricating properties of the hard and soft surface test, six different sizes Mega macromolecules (7% mega HPG-1 ~ 3, 23% mega HPG-1 ~ 3), respectively, motor oil Pennzoil 80w-90 , Synvisc one (so far approved by the FDA to treat osteoarthritis knee pain only a single injectionShot with viscoelastic replacement therapy drugs), Bovine synovial fluid lubricating effect was compared in the stainless steel surface. The results showed that The effect is similar to Synvisc one hard surface, but lower its viscosity. on the surface of the soft material, the authors selected to evaluate the lubricating properties of the articular cartilage Mega macromolecules, and compared with several other common soft interface lubricating fluid (e.g., saline, bovine synovial fluid, osteoarthritis who lubricating fluid) which proved, Mega macromolecules coefficient of friction (COF value) in the soft interface is similar to bovine synovial fluid, and significantly lower than the COF of human bones and joints lubricating fluid. Meanwhile, the COF Mega macromolecules of different molecular weight or different, having a higher molecular weight has a lower COF-3 COF values, and compared to two other Mega macromolecules, better stability. The results indicate that cell viability, Mega macromolecules have low cytotoxicity, indicating great potential for Mega molecules used in the human body. COF measured value
Summary: In this article, the authors reported in detail large dendrimer (Mega macromolecule) synthesized with a high degree of branching. This polymer has a nanoscopic scale, high water solubility, low intrinsic viscosity, density, viscosity independent of molecular weight, and good biocompatibility. Lubrication experiments which hard and soft surfaces, exhibit similar rheological properties of the fluid lubricant. Progress in the Synthesis of polymer chemistry offers unprecedented size and unique performance polymers and polymer structure. This development also prepared as a single entity large molecular structure, constructed from the assembly of higher order complex, the role of the matrix material provides synthetic and natural direction. References: Parambath Anilkumar et al Mega macromolecules as single molecule lubricants for hard and soft surfaces DOI:.. Doi.org/10.1038/s41467-020-15975-6 Link: https: //www.nature.com/articles / s41467-020-15975-6