Omniphobic Coatings Based on Amphiphilic Diblock Copolymers of 2-(Perfluorohexyl)ethyl Methacrylate and 2-Hydroxyethyl Methacrylate

Doklady Chemistry - Amphiphilic diblock copolymers of 2-(perfluorohexyl)ethyl methacrylate and 2-hydroxylethyl methacrylate have been synthesized for the first time by two-stage reversible...     

Synthesis of hydrophobically modified poly(acrylamides) in water-in-oil emulsions

High-molecular-mass hydrophobically modified poly(acrylamides) have been prepared via water-in-oil miniemulsion copolymerization of acrylamide and lauryl methacrylate initiated by 2,2′-azoisobutyronitrile. The incorporation of the hydrophobic comonomer into the polymer backbone is indirectly confirmed by the rheological and associative properties of polymer solutions. The copolymers prepared from the reaction mixtures containing less than 5 mol % lauryl methacry late demonstrate the associative behavior in aqueous solutions, as evidenced by fluorescence spectroscopy (a decrease in the polarity parameter of pyrene), static and dynamic light scattering (overestimated effective molecular masses and appearance of a peak due to aggregates), and rheological measurements (a rise of viscosity relative to that of the acrylamide homopolymer). A further increase in the content of lauryl methacrylate leads to formation of polymers possessing limited solubility in water. At the acrylamide-to-hydrophobic monomer equimolar ratio, homopolymers arise along with the insoluble copolymer.     

Investigation of the structure of polyphenylironsiloxane

The main features of the polyphenylironsiloxane (PPIS) structure were established by a combination of preparative fractionation, elemental analysis, gel-permeation chromatography,¹H NMR and UV spectroscopy, and destructive trimethylsilylation. Specimens of PPIS contain a large amount of oligophenylsiloxane, which is apparently closed polycyclic oligomers. PPIS macromolecules consist of oligomerc siloxane fragments linkedvia iron oxide fragments. PPIS is characterized by the high heterogeneity of macromolecules and their fragments.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 964–970, April, 1996.     

Hydrolytic condensation of trialkoxysilanes in the presence of alkali metal and copper(ii) ions. Influence of the reaction conditions on the structure of Cu/M organosiloxanes

The formation of polyhedral copper/sodium(potassium) organosiloxanes was examined as a result of hydrolytic condensation of organotrialkoxysilanes in the presence of copper(ii) and sodium or potassium ions. High selectivity of the synthesis of copper/sodium(potassium) organosiloxanes having desired structures can be achieved by choosing the reaction conditions.     

Synthesis of poly(arylene ether ketones) with terminal phenolic groups

Poly(arylene ether ketones) with preset molecular weights (reduced viscosity from 0. 2 to 0.82 dL g^–1) containing terminal phenolic groups were synthesized by the reactions of 4,4-difluorobenzophenone with bisphenol A or phenolphthalein in the presence of K₂CO₃ in N,N-dimethylacetamide. The influence of an excess of bisphenols on the molecular weights of the polymers obtained was studied. The structures of the polymers were confirmed by ¹H NMR spectroscopy. The molecular weight distributions of the polymers were determined.Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1958–1961, September, 2004.     

Sufficient conditions for optimality in problems with state constraints

In this paper the sufficient conditions for optimality are obtained for problems with state constraints. These constraints may be active. It means that the adjoint function may have points of discontinuity or jumps. Similar results in the case of absolutely continuous adjoint function were given by the author in [1] and [2].     

Simultaneous multiple capture in a conflict-controlled process

Sufficient conditions for simultaneous multiple capture are obtained in a linear non-stationary conflict-controlled process with different dynamic and inertial possibilities of all the participants.     

Nanosponges as products of N-alkylation of 4-vinylpyridine and poly(4-vinylpyridines) in dilute solutions

Hydrophilic ionic nanosponges with quaternary pyridinium groups are synthesized on the basis of 4-vinylpyridine and its polymer. Their synthesis relies on the use of bior polyfunctional agents alkylating pyridine in dilute solutions in a thermodynamically good solvent. Individual intramolecularly crosslinked soluble macromolecules with molecular masses from 6000 to 400000 are prepared at various degrees of dilution. 1,4-Bis(halomethyl)benzenes, p-vinylbenzyl chloride, and poly(vinylbenzyl chloride) are used as N-alkylating agents. The shapes and sizes of macromolecules are determined via the methods of diffusion, sedimentation, viscometry, dynamic light scattering, atomic force microscopy, and transmission electron microscopy.     

Molecular mass characteristics and solution behavior of some cardo polybenzimidazoles

The behavior of dilute solutions of cardo polybenzimidazoles based on 3,3′4,4′-tetraaminodiphenyl ether; 3,3′,4,4′-tetraaminodiphenyl sulfone; and 4,4′-diphenylphthalidedicarboxylic acid in solvents of various natures has been studied by the methods of dynamic light scattering, sedimentation, and viscometry. All of the polymers have been found to contain a microgel fraction. For each fraction, the diffusion coefficient and the particle size are determined. The experimental characteristics of macromolecules correspond to the conformational rigidity calculated by a computer simulation procedure.     

Group pursuit in Pontryagin’s nonstationary example

On the interval [t ₀, ∞), we consider the following group pursuit problem with one evader: 1 $$ z_i^{(l)} + a_1 (t)z_i^{(l - 1)} + a_2 (t)z_i^{(l - 2)} + \cdots + a_l (t)z_i = u_i - v, u_i ,v \in V, z_i^{(q)} (t_0 ) = z_i^q , $$ where z _i , u _i , v ∈ R ^v , (v ≥ 2), V is a strictly convex compact set in R ^v , the functions a ₁(t), a ₂(t), …, a _l (t) are continuous, i = 1, 2, …, n and q = 0, 1, …, l ? 1. Let ? _q (t, s) be the solution of the Cauchy problem $$ \begin{gathered} \omega ^{(l)} + a_1 (t)\omega ^{(l - 1)} + a_2 (t)\omega ^{(l - 2)} + \cdots + a_l (t)\omega = 0, \omega ^{(q)} (s) = 1, \hfill \\ \omega ^{(r)} (s) = 0, r = 0, \ldots q - 1,q + 1, \ldots ,l - 1, \hfill \\ \end{gathered} $$ and let $$ \xi _\iota (t) = \varphi _0 (t,t_0 )Z_i^0 + \varphi _1 (t,t_0 )Z_i^1 + \cdots + \varphi _{l - 1} (t,t_0 )Z_i^{l - 1} . $$ We prove that if there exist continuous functions α _i (t) and ξ _i ¹ (t) such that the ξ _i ¹ (t) are Bohr almost periodic on [t ₀, ∞), α _i (t) > 0 for all t ≥ t ₀, lim _t→∞(ξ _i ¹ (t) ? α _i (t)ξ _i (t)) = 0, lim _t→∞(min _i α _i (t) ∝ _t0 ^t |? _l?1(t, s)| ds) = ∞, and there exist points h _i ⁰ ∈ H _i ¹ = {ξ _i ¹ (t), t ∈ [0, ∞)} such that 0 ∈ Int co{h _i ⁰ }, then the pursuit problem with evader discrimination is solvable.