Synthesis and functional properties of thermosensitive polymer derivatives of proteins

N,N-Diethylacrylamide-N-acryloylphthalimide copolymers have been synthesized. The LCST of the synthesized copolymers decreases with increase in both the molecular mass of the copolymers and the content of more hydrophobic N-acryloylphthalimide units. Through the reaction of the copolymers with the proteinase enzyme inhibitor, ovomucoid, the polymer derivatives of protein have been prepared. It has been shown that the biological activity of ovomucoid and the LCST of polymer derivatives increase with the amount of the immobilized ovomucoid. The effect of biologically active media on the LCST values of polymer derivatives has been studied.     

Synthesis of <Emphasis Type="Italic">N</Emphasis>-vinylpyrrolidone copolymers with 2-aminoethyl methacrylate as drug carriers

Radical copolymerization of N-vinylpyrrolidone and 2-aminoethyl methacrylate hydrochloride has been studied. Molecular and hydrodynamic characteristics of the resulting copolymers have been determined, and their structure has been confirmed. Conditions favoring conversion of these copolymers into copolymers of N-vinylpyrrolidone with 2-aminoethyl methacrylate of different composition have been elucidated. The suitability of the prepared copolymers as polymeric carriers of monofluoroquinolone ofloxacin has been demonstrated.     

Effect of solvent nature on free-radical copolymerization of N,N-diallyl-N,N-dimethylammonium chloride and maleic acid

The free-radical copolymerization of N,N-diallyl-N,N-dimethylammonium chloride with maleic acid in DMSO proceeds to yield statistical copolymers. When the reaction is carried out in methanol, the copolymers of constant compositions (N,N-diallyl-N,N-dimethylammonium chloride: maleic acid = 2: 1) are formed over a wide range of comonomer ratios in the starting mixture. The formation of alternating copolymers in this case may be attributed to formation of donor-acceptor complexes between the comonomers in the methanol solution, as evidenced by UV spectrophotometry. The kinetic features of the process have been investigated, and the relative activities of the monomers have been assessed. ¹³C NMR studies have demonstrated that, regardless of the solvent nature, both double bonds of N,N-diallyl-N,N-dimethylammonium chloride are involved in copolymerization via intermolecular cyclization accompanied by formation of pyrrolidinium structures.     

Copolymerization of N,N-diallyl-N,N-dimethylammonium chloride and vinyl acetate

The free-radical copolymerization of N,N-diallyl-N,N-dimethylammonium chloride with vinyl acetate in DMSO, methanol, and a methanol-water (70: 30, mol %) mixture proceeds to yield statistical copolymers. The nature of solvents significantly affects the reactivity ratios of the comonomers. N,N-Diallyl-N,N-dimethylammonium chloride shows a higher reactivity than vinyl acetate. The kinetic features of the processes have been investigated, and the structure and properties of the copolymers have been studied.     

Controlled radical copolymerization of N-vinylpyrrolidone with 1,1,1,3,3,3-hexafluoroisopropyl-α-fluoroacrylate

Narrow disperse copolymers of N-vinylpyrrolidone with 1,1,1,3,3,3-hexafluoroisopropyl-α-fluoroacrylate have been prepared for the first time by reversible addition fragmentation chain transfer pseudo-living radical polymerization in the presence of benzyl dithiobenzoate. The relative activities of the monomers indicating the occurrence of alternating copolymerization have been estimated. The copolymerization of equimolar N-vinylpyrrolidone-1,1,1,3,3,3-hexafluoroisopropyl-α-fluoroacrylate mixtures shows typical features of reversible addition fragmentation chain transfer pseudoliving radical polymerization: deceleration of polymerization compared to the classical radical process, degeneration of the gel effect, successive increase in the number-average molecular mass with conversion, and formation of narrow disperse copolymers.     

Preparation of a thermally phase-separating copolymer,poly(N-isopropylacrylamide-co-N-acryloxysuccinimide), with a controlled number of active esters per polymer chain

N-isopropylacrylamide and N-acryloxysuccinimide have been copolymerized in various mixtures of terrahydrofuran and toluene using azobisisobutyronitrile as initiator. Polymerization has been conducted for 24 h at 50°C under a slightly positive pressure of nitrogen. The copolymers were assayed for active ester content by measuring the UV absorbance (259 nm) of N-hydroxysuccinimide anion, generated by reacting the copolymers with N-isopropylamine in dimethylformamide and dissolving the resulting mixture in 0.1M HEPES buffer, pH 7.5. The molecular weight and its distribution have been estimated by gel permeation chromatography. The active ester content was found to be equivalent to the comonomer feed ratio, and the major factor controlling the molecular weight was the ratio of tetrahydrofuran to toluene. Thus, the number of active esters per polymer chain could be controlled by adjustment of the comonomer feed ratio and the ratio of tetrahydrofuran to toluene. Monomer reactivity ratios for copolymerization of N-isopropylacrylamide with N-acryloxysuccinimide were also estimated. These copolymers are useful for immobilizing binding ligands such as antibodies for subsequent thermally induced precipitation immunoassays and bioseparation processes.     

New green fluorescent polymer sensors for metal cations and protons

A new 4-(N-methylpiperazine)-N-allyl-1,8-naphthalimide with intense yellow-green fluorescence has been synthesized. Then it has been copolymerized with styrene and methylmetacrylate. The photophysical characteristics of the fluorescent dye and its copolymers (poly(St-co-NI) and poly(MAA-co-NI)) have been determined viewing their sensor properties for protons and transition metal cations (Cu²⁺, Fe³⁺ and Zn²⁺). Fluorescence enhancement is the photophysical response of the 4-(N-methylpiperazine)-N-allyl-1,8-naphthalimide to the presence of metal cations and protons, while fluorescence quenching is observed for both copolymers.     

Synthesis of poly(N-vinylpyrrolidone) and N-vinylpyrrolidone-methyl methacrylate copolymers in the presence of C-phenyl-N-tert-butylnitrone

The free-radical polymerization of N-vinylpyrrolidone and its copolymerization with methyl methacrylate have been studied at 60°C in the presence of C-phenyl-N-tert-butylnitrone as a chain-growth regulator. It has been shown that the above additive makes it possible to synthesize poly(N-vinylpyrrolidone) and its copolymers without any gel effect and to control molecular-mass characteristics of homo-and (co)polymers.     

Dilute solutions of polyelectrolytes—IV. Unperturbed dimensions of N,N-diethylacrylamide-N,N-dimethyldiallylammonium chloride copolymers

The behaviour of copolymers of N,N-diethylacrylamide with N,N-dimethyldiallylammonium chloride in aqueous NaCl solution has been studied by light-scattering. The parameters characterizing the short- and long-range interactions have been calculated. The influence of copolymer composition on the gyration radius and unperturbed dimensions shows that the macromolecules have maximum flexibility for a composition near equimolar. This behaviour was attributed to decrease of both the electrostatic repulsions and the steric hindrance of the structural units, as a result of pronounced alternation.     

Aminolyses of reactive monomers and polymers—II. N-hydroxyphthalimide esters

Some N-hydroxyphthalimide esters of N-methacrylated ω-amino acids have been prepared and copolymerized with N-(2-hydroxypropyl)methacrylamide. The rates of aminolysis of monomers and copolymers have been compared.     

Electroactivity, electrochemical stability and electrical conductivity of multilayered films containing poly(3,4-ethylendioxythiophene) and poly(N-methylpyrrole)

Multilayered systems of poly(3,4-ethylendioxythiophene) and poly(N-methylpyrrole) have been prepared using a layer-by-layer electrodeposition technique. The electrochemical and electrical properties of films formed by 3, 5, 7 and 9 layers have been characterized and compared with those of pure polymers and copolymers prepared from mixtures of 3,4-ethylendioxythiophene and N-methylpyrrole with various concentration ratios. Results indicate that the electroactivity and electrical stability of the multilayered systems are higher than those of both poly(3,4-ethylendioxythiophene) and copolymers. Furthermore, these electrochemical properties improve when the number of layers increases. On the other hand, the electrical conductivity of the multilayered systems is slightly lower than that of pure poly(3,4-ethylendioxythiophene), and significantly higher than those of poly(N-methylpyrrole) and copolymers.     

Conformational and dynamic characteristics of copolymers of N,N-dimethylaminoethyl methacrylate and 2-deoxy-2-methacrylamido-D-glucose

The conformational and relaxation properties of N,N-dimethylaminoethyl methacrylate and 2-deoxy-2-methacrylamido-D-glucose copolymers in solutions are studied by the methods of molecular hydrodynamics (sedimentation, diffusion, viscometry), polarized luminescence, and flow birefringence. Kuhn-Mark-Houwink equations are obtained, and Kuhn statistical segment lengths at various degrees of protonation of amino groups are estimated. It is found that there is a correlation between the Kuhn statistical segment length and the intramolecular mobility of the copolymers.     

Recent progress in controlled radical polymerization of N-vinyl monomers

This review summarizes recent advances in the controlled radical polymerization of N-vinyl monomers, such as N-vinylcarbazole, N-vinylindole derivatives, N-vinylpyrrolidone, N-vinylcaprolactam, N-vinylformamide, N-vinylacetoamide derivatives, N-vinyl(na)phthalimides, N-vinylimidazolium salts, and N-vinyltriazoles. Recent significant progress of controlled radical polymerization of these N-vinyl monomers has allowed for the synthesis of well-defined functional polymers having various architectures, including block copolymers, branched polymers (stars, star block copolymers, miktoarm star copolymers, and graft copolymers), and hybrids. Characteristic properties, assembled structures, and three-dimensional architectures of these functional polymers derived from N-vinyl monomers are briefly introduced.     

ATRP of 3-(triethoxysilyl)propyl methacrylate and preparation of “stable” gelable block copolymers

ATRP of a gelable monomer, 3-(triethoxysilyl)propyl methacrylate (TESPMA), mediated by CuBr/N,N,N’,N’’,N”-pentamethyldiethylenetriamine (PMDETA) using ethyl 2-bromoisobutyrate (2-EBiB) as initiator was studied. The results indicate that polymerization follows the first-order kinetic. PolyTESPMA (PTESPMA) is much more stable to moisture which is important for exploring the properties of its block copolymer. A series of PEO-b-PTESPMA block copolymers with different composition were prepared. Self-assembly of PEO-b-PTESPMA has also been explored in a mixture of methanol and water and polymeric vesicles have been obtained. By introducing the gelation catalyst, the block copolymer vesicles can be stabilized by the silica networks.     

Photoinduced optical anisotropy in azobenzene methacrylate block copolymers: Influence of molecular weight and irradiation conditions

The photoinduced anisotropy in a series of azomethacrylate block copolymers with different molecular weights and azo contents has been investigated under several irradiation conditions. Depending on molecular weight and composition, different microstructures (disordered, lamellar, spherical) appear, due to block microsegregation. Measurements of birefringence (Δn) induced with linearly polarised 488 nm light show that the highest (and stable) Δn_N values (birefringence normalised to the azo content) are achieved in copolymers with a lamellar structure. Lower Δn_N are obtained in the copolymers in which azobenzene units segregate to nano spheres and the lowest (and less stable) Δn_N values, appear in disordered systems not showing any defined microstructure. Besides, higher Δn_N is obtained in the copolymers with larger molecular weight of the poly (methyl methacrylate) and the azo polymer blocks, both in the microspheres segregated polymers as well as in those without a clear microstructure. This behaviour is consistent with that of the photoinduced order of azobenzene units obtained from dichroism measurements. Irradiation temperature (from 30 to 90 °C) and light power (from 100 to 500 mW/cm²) also influence the photoinduced response. Photoinduced Δn_N growth rate is faster when both temperature and irradiation power increase. Furthermore, birefringence is only induced at temperatures up to 90 °C, the maximum value being obtained at about 70 °C. No clear dependence of the final Δn_N value with light power has been found.     

Synthesis and characterization of novel vinyl copolymers containing N-vinylphthalimide: Comonomers reactivity ratios and thermal stability

N-Vinylphthalimide (NVPh) was copolymerized with p-methylstyrene (PMS), p-methoxystyrene (PMOS) and p-chlorostyrene (PClS) at 60 °C, with 2,2′-azo-bis-isobutyronitrile as an initiator. Copolymer composition was determined by elemental analysis in case of the N-vinylphthalimide and p-methylstyrene comonomer pair, whereas proton nuclear magnetic resonance was used for the analysis of the two other copolymers.The reactivity ratios for each comonomer pair were estimated by the classical Fineman-Ross and Kelen-Tüdõs linear techniques. These data showed that N-vinylphthalimide was less reactive in all the cases and that the comonomer distribution, that was basically random in the poly(N-vinylphthalimide-co-p-methylstyrene) and poly(N-vinylphthalimide-co-p-chlorostyrene) copolymers, was rather alternate in the third poly(N-vinylphthalimide-co-p-methoxystyrene) copolymer. The difference observed in the reactivity ratios was discussed in reference to the structure of the comonomer units and the parent radicals. The thermal properties of the copolymers and model homopolymers were investigated by differential scanning calorimetry and thermogravimetric analysis.     

New N-vinylamide-based polymers for the preconcetration of nitrophenols from aqueous media

New cross-linked copolymer with molecular imprints of 4-nitrophenol have been synthesized by the radical polymerization of cyclic N-vinyl amides and ethylene glycol dimethacrylate. Sorption characteristics of the obtained polymers depend on the nature of the functional monomer, ratio of components in the prepolymerization mixture, pH of solution, and temperature. It has been established that N-vinylpyrrolidone-based copolymers provide higher selectivity of 4-nitrophenol extraction than N-vinylcaprolactam-based products.     

Synthesis and Characterization of Catechol-Containing Polyacrylamides with Adhesive Properties

In this study, a row of four analogous dopamine acryl- and methacrylamide derivatives, namely N-(3,4-dihydroxyphenyethyl) acrylamide, N-(3,4-dihydroxyphenyethyl) meth acrylamide, N-phenethyl methacrylamide, N-(4-hydroxyphenethyl) methacrylamide were synthesized and characterized by ¹H-NMR and ¹³C-NMR, followed by further solvent-based radical polymerization with N-hydroxyethyl acrylamide. All copolymers were characterized by ¹H-NMR, dynamic differential calorimetry, and gel permeation chromatography. The dependency of the used comonomer ratios to the molecular mass of the corresponding copolymers has been described. The synthesis of the various polymers serves as a feasibility study and provides important data for a future biometric application in the medical field. We synthesized N-(3,4-dihydroxyphenyethyl) acrylamide copolymer up to 80 mol% by free radical polymerization without using any protecting groups. All polymers show identical perfect adhesive properties by a simple scratch test. Further, the monomers were used as a photo reactive glue formulation to test its adherence to a medical titanium surface sample by tensile shear test.     

Preparation and some properties of diamine-diacid type alternating copolyamides

The polycondensations of N,N′-bis-(6-aminohexyl)oxamide, N,N′-bis-(6-aminohexyl) succinimide and N,N′-bis(6-aminohexyl)-sebacamide, with p-nitrophenyl adipate in 1,2,4-trichlorobenzene solution, using relatively low temperature (100°) to avoid the amide exchange reactions, gave alternating copolyamides corresponding to (6-6) (6-2), (6-6) (6-4) and (6-6) (6–10) nylons. These copolymers have melting points between those of their corresponding homopolyamides, whereas the random copolymers melt lower than either of the homopolymers. The microstructure of the copolymers seems to be modified by heat treatment below the melting points. Amide exchange reactions occur when they are heated to melting. C¹³ spectra allowed differentiation between the CO groups of the two constituent units of the copolymers, but not between the alternating and the random copolymers.     

Synthesis and characterization of thermosensitive copolymers for oral controlled drug delivery

Poly(N-isopropylacrylamide) (PNIPAAm) copolymers were synthesized in order to obtain co-polymers with a phase transition temperature slightly higher than the physiological temperature, as required by a new drug delivery concept described in a previous paper. Six hydrophilic comonomers bringing about a rise of the phase transition temperature were evaluated. The synthesized copolymers were characterized and the influence of the type and of the amount of the used comonomer on the phase transition temperature was discussed. Among the comonomers, Acrylamide (AAm), N-methyl-N-vinylacetamide (MVA), N-vinylacetamide (NVA), and N-vinyl-2-pyrrolidinone (VPL) were found to be capable to raise the phase transition temperature to a value slightly higher than 37 °C and to have adequate phase transition behavior. The selected four copolymers were subjected to an additional purification step that should make them fit to use as a controlling agent in drug delivery systems.