Conformation properties of poly(N,N-dimethylaminoethyl methacrylate) macromolecules in various solvents

Abstract

Poly(N,N-dimethylaminoethyl methacrylate) macromolecules in the un-ionized and ionized states were studied by methods of molecular hydrodynamics, optics, and polarized luminescence. The conformation, relaxation, and optical parameters of the macromolecules were determined. The Mark-Kuhn-Houwink equations were obtained for the intrinsic viscosity and diffusion and sedimentation coeffi cients. Poly(N,N-dimethylaminoethyl) methacrylate (PDMAEM) attracts researchers' attention for a long time. It exhibits antimicrobial and fungicidal properties; it is one of the most effective polymers for the DNA transport; it is also used as flocculant in mining industry [1][2][3][4][5][6][7]. PDMAEM is a weak base. Its temperaturesensitive properties and conformation of macromolecules are determined by the nature of the solvent (pH, ionic strength, kind of counteranions) [8][9][10][11][12][13][14]. Signifi cant role is also played by the molecular weight and architecture of PDMAEM macromolecules [12].Determination of the molecular weights and dimensions of macromolecules of amphiphilic polymers and polyelectrolytes still involves problems because of the occurrence of intra-and intermolecular interactions. This particularly concerns polyelectrolytes, because they are characterized by two oppositely acting factors: hydrophobic interaction and Coulomb repulsion. The fi rst factor leads to enhancement of intra-and intermolecular interactions which decrease the hydrodynamic volume, whereas the electrostatic forces tend to increase the volume of polymeric coils, i.e., the hydrodynamic volume. Salt additions can shield the polyelectrolytic effect but enhance the hydrophobic intramolecular interactions. Hydrophobic contacts can be broken by adding organic solvents or surfactants.In this study we determined the molecular, conformation, optical, and relaxation properties of PDMAEM in the forms of the base and salt in dilute solutions. To this end, we used the methods of molecular hydrodynamics (sedimentation, diffusion, viscometry) and optics (fl ow birefringence, polarized luminescence). EXPERIMENTAL PDMAEM was prepared by free-radical polymerization of DMAEM in benzene, toluene, or isopropanol solution at 60°С with azobis(isobutyronitrile) (AIBN) as initiator or in aqueous solution at 25°С with a 1 : 1 mixture of (NH 4 ) 2 S 2 O 8 and N,N,N',N'-tetramethylethylenediamine as initiator (Table 1).The polymer with a luminescence label was prepared by free-radical copolymerization of DMAEM with 9-anthrylmethylmethacrylamide; the concentration of the monomers in the isopropanol solution was 15 wt %, and the AIBN concentration, 1.5 wt % relative to the monomers. The content of luminescence labels in the polymer did not exceed 0.2 mol %.The intrinsic viscosities were measured by the standard procedure in the Ostwald capillary viscometer. For

New water‐soluble copolymers of 2‐methacryloyloxyethyl phosphorylcholine for surface modification

“…The τ IMM values obtained for VP and MAG homopolymers (24 and 31 ns, respectively, see Experiments 5, 2, 1, Table 3) are typical of linear macromolecules with bulky side substituents that contain proton donor and/or proton acceptor groups 26 . The τ IMM for MPC homopolymer (poly‐MPC), which contains oppositely charged groups in each side chain, was found to be 35 ns; it is close to the τ IMM value obtained for protonated poly‐2‐(dimethylamino)ethyl methacrylate (PDMAEM) 27 . Apparently, high values of τ IMM (35 ns) found for charged polycations can be explained as follows.…”

“…At short distances, electrostatic interaction between charged groups in non‐polar environment leads to more pronounced “stiffening” of a chain than in the case when charged groups are exposed to water. It was demonstrated that statistical dimensions of PDMAEM macromolecules deviate from the Gaussian values 27 . The authors explained this deviation by the residual electrostatic short‐range interactions, since the long‐range electrostatic interactions were shielded by adding a low molecular weight salt to the solvent.…”

“…26 The τ IMM for MPC homopolymer (poly-MPC), which contains oppositely charged groups in each side chain, was found to be 35 ns; it is close to the τ IMM value obtained for protonated poly-2-(dimethylamino)ethyl methacrylate (PDMAEM). 27 Apparently, high values of τ IMM (35 ns) found for charged polycations can be explained as follows. At short distances, electrostatic interaction between charged groups in non-polar environment leads to more pronounced "stiffening" of a chain than in the case when charged groups are exposed to water.…”

“…It was demonstrated that statistical dimensions of PDMAEM macromolecules deviate from the Gaussian values. 27 The authors explained this deviation by the residual electrostatic short-range interactions, since the long-range electrostatic interactions were shielded by adding a low molecular weight salt to the solvent.…”

Incentives of Using the Hydrodynamic Invariant and Sedimentation Parameter for the Study of Naturally- and Synthetically-Based Macromolecules in Solution

“…Color and symbol assignments for naturally-based macromolecules: Black-Rigid, Xanthan (squares) [25], Chitosan (circles) [26,27], Schizophyllan (triangles up) [28]; Blue-Semi-Flexible, Pectin (squares) [29,30], Chitosan (circles) [31][32][33][34], Chitin (triangles up) [35], Cellulose (triangles down) [12,[36][37][38][39][40][41], Heparin (diamonds) [42], Ficoll400 (triangles left) [43]; Green-Flexible, Glucan (squares) [44], Mannan (circles) [45], Pullulan (triangles up) [46], Carrageenan (triangles down) [47], Polyvinylsaccharide (diamonds) [48,49]; Red-Branched, Glucan (squares) [50], Lysin (circles) [51]. Color and symbol assignments for synthetically-based macromolecules: Blue-Semi-Flexible, Polyelectrolyte (squares), cationic [52]; Green-Flexible, Polyelectrolyte (squares), cationic [53][54][55][56][57][58][59][60][61][62], anionic [63], Poly(ethylene) glycol (PEG) (circles) [14], Poly(2-alkyl-2-oxazoline) (POx)/Poly(oligo(2-ethyl-2-oxazoline)) based polymers (triangles up) [13,…”