initial monomer
Recently Published Documents


TOTAL DOCUMENTS

30
(FIVE YEARS 9)

H-INDEX

8
(FIVE YEARS 2)

2021 ◽  
Vol 0 (4) ◽  
pp. 25-29
Author(s):  
A.I. Alikhanova ◽  
◽  
R.Sh. Rasulzade ◽  

The paper is devoted to the study of regularities of radical copolymerization reactions of unsaturated cyclic N,N'-bisimides (M1) with styrene (M2), the study of dependence of copolymerization reaction rate, composition of obtained copolymers, composition and estimated molecular weight on the composition of the initial monomer mixture. With the increase of bismaleimide amount in the initial monomer mixture a decrease of copolymerization reaction yield and molecular weight of the obtained copolymers was observed. This fact can be explained by active participation of bismaleimide in chain transfer in radical copolymerization reaction. The composition of the obtained copolymers in all cases is rich in styrene links


Polymers ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 2021
Author(s):  
Jonas Mätzig ◽  
Marco Drache ◽  
Sabine Beuermann

High-temperature acrylate polymerizations are technically relevant, but yet not fully understood. In particular the mechanism and the kinetics of the thermal self-initiation is a topic of current research. To obtain more detailed information the conversion dependence of the polymerization rate, rbr, is determined via in-line DSC and FT-NIR spectroscopy for reactions in bulk and in solution at temperatures ranging from 80 to 160 °C. Solution polymerizations revealed that dioxane is associated with the highest rbr, while aromatic solvents result in the lowest values of rbr. Interestingly, rbr for polymerizations in solution with dioxane depends on the actual monomer concentration at a given time in the system, but is not depending on the initial monomer concentration. The overall rate of polymerization in bulk and in solution is well represented by an equation with three or four parameters, respectively, being estimated by multiple linear regression and the temperature as additional parameter.


Processes ◽  
2020 ◽  
Vol 8 (11) ◽  
pp. 1352
Author(s):  
Ikenna H. Ezenwajiaku ◽  
Emmanuel Samuel ◽  
Robin A. Hutchinson

The radical homopolymerization kinetics of 3-(methacryloylaminopropyl) trimethylammonium chloride (MAPTAC) and its batch copolymerization with nonionized acrylic acid (AA) in aqueous solution are investigated and modeled. The drift in monomer composition is measured during copolymerization by in situ NMR over a range of initial AA molar fractions and monomer weight fractions up to 0.35 at 50 °C. The copolymer becomes enriched in MAPTAC for monomer mixtures containing up to 60 mol% MAPTAC, but is enriched in AA for MAPTAC-rich mixtures; this azeotropic behavior is dependent on initial monomer content, as electrostatic interactions from the cationic charges influence the system reactivity ratios. Models for MAPTAC homopolymerization and AA-MAPTAC copolymerization are developed to represent the rates of monomer conversion and comonomer composition drifts over the complete range of experimental conditions.


2020 ◽  
Vol 869 ◽  
pp. 21-27
Author(s):  
Zakhirat Kh. Sultigova ◽  
Zareta I. Inarkieva ◽  
Rima Ch. Bazheva ◽  
Arsen M. Kharaev ◽  
Madina Yalkhoroeva

The modified aromatic polyethersulfones are synthesized. It is shown that the property of the obtained polymers depends on the ratio of the starting monomers. The presence in the initial monomer of two chlorine atoms in combination with an unsaturated bond provides the polyethersulfones based on it with high fire resistance and good physical and chemical properties, including frost resistance.


Polymers ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 926
Author(s):  
Matthew A. Bone ◽  
Terence Macquart ◽  
Ian Hamerton ◽  
Brendan J. Howlin

Materials science is beginning to adopt computational simulation to eliminate laboratory trial and error campaigns—much like the pharmaceutical industry of 40 years ago. To further computational materials discovery, new methodology must be developed that enables rapid and accurate testing on accessible computational hardware. To this end, the authors utilise a novel methodology concept of intermediate molecules as a starting point, for which they propose the term ‘symthon’ (The term ‘Symthon’ is being used as a simulation equivalent of the synthon, popularised by Dr Stuart Warren in ‘Organic Synthesis: The Disconnection Approach’, OUP: Oxford, 1983.) rather than conventional monomers. The use of symthons eliminates the initial monomer bonding phase, reducing the number of iterations required in the simulation, thereby reducing the runtime. A novel approach to molecular dynamics, with an NVT (Canonical) ensemble and variable unit cell geometry, was used to generate structures with differing physical and thermal properties. Additional script methods were designed and tested, which enabled a high degree of cure in all sampled structures. This simulation has been trialled on large-scale atomistic models of phenolic resins, based on a range of stoichiometric ratios of formaldehyde and phenol. Density and glass transition temperature values were produced, and found to be in good agreement with empirical data and other simulated values in the literature. The runtime of the simulation was a key consideration in script design; cured models can be produced in under 24 h on modest hardware. The use of symthons has been shown as a viable methodology to reduce simulation runtime whilst generating accurate models.


2020 ◽  
Vol 22 (9) ◽  
pp. 5347-5354
Author(s):  
Bing-Yu Li ◽  
Li Zhao ◽  
Zhong-Yuan Lu

The interfacial tension, initial monomer concentration, and reaction probability can greatly influence the microscopic characteristics of the Janus nanoparticle (JNP) structure. The asymmetric initial monomer concentration in solution and the reaction probability can be used to control the syntheses of asymmetric JNPs.


2020 ◽  
Vol 11 (14) ◽  
pp. 2595-2604 ◽  
Author(s):  
Hans R. Kricheldorf ◽  
Steffen M. Weidner ◽  
Felix Scheliga

The results of this study show that even at the highest initial monomer concentration (IMC) complete cyclization of polymer chains can be achieved at 100% conversion.


2019 ◽  
Vol 21 (Supplement_6) ◽  
pp. vi96-vi97
Author(s):  
Catherine Vasey ◽  
Vincenzo Taresco ◽  
Stuart Smith ◽  
Cameron Alexander ◽  
Ruman Rahman

Abstract Despite multimodal treatment, the median survival of Glioblastoma multiforme (GBM) patients remains less than 15 months, in considerable part due to diffusely infiltrative disease. Better treatment methods are necessary to eradicate residual tumour burden remaining beyond the resection cavity boundary. It is hypothesised that incorporating drug-loaded polymer pro-drug nanoparticles into a biodegradable microparticulate paste will lead to efficacious local delivery. We report the formulation of numerous self-assembling cytocompatible nanoparticles, based on different linear and branched polymeric architectures, amenable for localised intra-cavity delivery post-surgery. The polymers were synthesised by ring-opening polymerisation with organic catalysts, leading to controlled reaction kinetics and greater potential biomedical applicability. A simple nanoprecipitation technique was employed to gain nanoparticles with the size range of 60–130 nm, depending on the initial monomer ratios and polymeric architectures. Successful biocompatibility studies of the self-assembling nanoparticles have been carried out in vitro on the U87 glioma cell line. We demonstrated that copolymerisation of a monomer with functional capability enabled the successful conjugation of doxorubicin to the polymer chain. We will discuss strategies to incorporate pH-sensitive linkers to the polymeric backbone, which would allow controlled drug release in acidic microenvironments. Based on an increasing understanding of GBM intra-tumour heterogeneity, the capability to deliver multiple therapeutic moieties from single formulations is clinically-relevant. Thus, we hypothesised that polymers with a greater degree of branching over traditional linear structures would lead to greater drug loading, and successfully tested this hypothesis through the encapsulation of olaparib. Future work will assess the efficacy of the polymer pro-drug nanoparticles against both commercial and primary cell lines, and safety/efficacy of intra-cavity delivery using orthotopic syngeneic allografts, thus giving a more therapeutically-relevant insight into the activity of the formulations. This is the first study incorporating polymer pro-drugs of this type into an existing localised micro-scale delivery system for GBM therapies.


Pharmaceutics ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 378 ◽  
Author(s):  
Justyna Odrobińska ◽  
Katarzyna Niesyto ◽  
Karol Erfurt ◽  
Agnieszka Siewniak ◽  
Anna Mielańczyk ◽  
...  

The new polymeric systems for delivery in cosmetology applications were prepared using self-assembling amphiphilic graft copolymers. The synthesis based on “click” chemistry reaction included grafting of azide-functionalized polyethylene glycol (PEG-N3) onto multifunctional polymethacrylates containing alkyne units. The latter ones were obtained via atom transfer radical polymerization (ATRP) of alkyne-functionalized monomers, e.g., ester of hexynoic acid and 2-hydroxyethyl methacrylate (AlHEMA) with methyl methacrylate (MMA), using bromoester-modified retinol (RETBr) as the initiator. Varying the content of alkyne moieties adjusted by initial monomer ratios of AlHEMA/MMA was advantageous for the achievement of a well-defined grafting degree. The designed amphiphilic graft copolymers P((HEMA-graft-PEG)-co-MMA), showing tendency to micellization in aqueous solution at room temperature, were encapsulated with arbutin (ARB) or vitamin C (VitC) with high efficiencies (>50%). In vitro experiments carried out in the phosphate-buffered saline solution (PBS) at pH 7.4 indicated the maximum release of ARB after at least 20 min and VitC within 10 min. The fast release of the selected antioxidants and skin-lightening agents by these micellar systems is satisfactory for applications in cosmetology, where they can be used as the components of masks, creams, and wraps.


2018 ◽  
Author(s):  
Maria Hoyer ◽  
Jose Rafael Cabral Correia ◽  
Don C. Lamb ◽  
Alvaro H. Crevenna

ABSTRACTActin filament dynamics underlie key cellular processes, such as cell motility. Although actin filament elongation has been extensively studied under the past decades, the mechanism of filament nucleation remains unclear. Here, we immobilized gelsolin, a pointed-end nucleator, at the bottom of zero-mode waveguides to directly monitor the early steps of filament assembly. Our data revealed extensive dynamics and that only one, of two populations, elongates. Annalysis of the kinetics revealed a more stable trimer but a less stable tetramer in the elongating population compared to the non-elongating one. Furthermore, blocking flattening, the conformational change associated with filament formation, prevented the formation of both types of assemblies. Thus, flattening and the initial monomer arrangement determine gelsolin-mediated filament initiation.


Sign in / Sign up

Export Citation Format

Share Document