Adsorption of plasma proteins to the derivatives of polyetherurethaneurea carrying tertiary amino groups in the side chains

Polyetherurethaneureas carrying tertiary amino groups in the side chains were synthesized, quaternized, and heparinized. The adsorption of plasma proteins to the polyurethane derivatives was investigated using Fourier-transform infrared, surface fluorescence, ultraviolet, and circular dichroism spectroscopy. Bovine gamma-globulin and bovine plasma fibrinogen were easily adsorbed to hydrophobic polyurethanes and denatured. It was found that the beta structure was generated during the irreversible conformational change of the proteins on adsorption to hydrophobic polyurethane materials. On the other hand, bovine serum albumin was easily adsorbed to hydrophilic quaternized and heparinized polyurethanes without a serious conformational change. The conclusion was drawn that a polymer material that selectively adsorbs bovine serum albumin in a native state could be antithrombogenic.     

Synthesis and thermodynamic studies on the protonation of a new polymeric amino diacid

A linear poly(amido-amine) carrying a malonic acid moiety in the side chain of the repeating unit was synthesized and characterized. Its behaviour in aqueous solution was investigated by potentiometric, viscometric and calorimetric techniques. The basicity constant relative to the tertiary nitrogen atom decreases linearly by increasing the overall degree of protonation, while the tendency of each carboxylate ion to accept a proton is influenced by the presence of the neighbouring negative charge. The change of the basicity constants with the degree of protonation is due to entropic terms leading to energetics of protonation independent of the degree of protonation.     

Synthesis and properties of polymers containing 4- or 4′-chalconecarbonyl groups in side chains

Photocrosslinkable polymers containing chalconecarbonyl units were prepared. 2-Methacryloyloxyethyl 4-chalconecarboxylate ( 1 ) and 2-methacryloyloxyethyl 4′chalconecarboxylate ( 2 ) were synthesized and polymerized by a radical initiator. 1 was copolymerized with methyl methacrylate. The properties of the resulting polymers as photosensitive resins are described.     

Comb-like methacrylamide polymers containing condensates of amino acids and azobenzene moieties in the side chains

The synthesis and free-radical polymerization of 4-(6-methacryloylaminohexanoylamino)azobenzene ( 4 ), 4-(11-methacryloylaminoundecanoylamino)azobenzene ( 5 ), and 4-[11-(11-methacryloylaminoundecanoylamino)undecanolyamino]azobenzene ( 6 ), are described. The monomers; the corresponding homopolymers 8–10 , poly(4-methacryloylaminoazobenzene) ( 7 ), and copolymers of 5 with stearyl acrylate, 11 , and methyl methacrylate, 12 , were characterized by DSC and TG analysis. Homopolymers with relatively long amino acid spacer groups were crystalline, the copolymer 12 was not crystalline. The UV-induced E/Z photoisomerization and the thermal back-isomerization were investigated for some of the monomers and polymers in solution and in solid films and correlated with the structures of the compounds. After photoisomerization the crystallinity of homopolymer 9 vanished because of disordering of the azobenzene side chains.     

Synthesis and characterization of copolymers from acrylamide and methacrylamide carrying peptide side chains

N-Benzylacrylamide ( 1 ) and N-(3-aminopropyl)methacrylamide hydrochloride ( 2 ) were copolymerized to give poly[N-benzylacrylamide-co-N-(3-aminopropyl)methacrylamide hydrochloride] ( 3 ). The reactivity ratios r₁ and r₂ were found to be r₁ = 0,87 and r₂ = 0,66 in which r₁r₂ < 1 indicate a statistical copolymer composition. Dehydrochlorination of the copolymer liberated primary amino groups to which peptide chains were grafted by reaction with L -alanine-NCA. The solubility of the resulting graft copolymers ( 6 ) in trifluoroacetic acid allowed the characterization of the products both by NMR and polarimetry. These methods and IR spectroscopy showed that the primary amino groups have only partially participated in initiating the NCA polymerization. The length of grafted peptide chains was found to be always higher than the one calculated from the ratio [NCA]/[NH₂].     

Synthesis and homopolymerization of methacrylic esters carrying dendritic polypyridines as side groups

Pyridine‐based dendrons (up to the third generation) having an OH group at the focal point react with CO and propyne in the presence of a palladium catalyst to give the corresponding methacrylic esters in high yield. The new methacrylic monomers have been homopolymerized with a free radical initiator. While the polymerization of [G1] ‐ and [G‐2] ‐methacrylic esters give high molecular weight polymers, the [G‐3] ‐methacrylic ester affords only oligomeric products.     

Synthesis of a new family of poly(amido-amine)s carrying poly(oxyethylene) side chains

A new class of water-soluble poly(amido-amine)s (PAA's) carrying poly(oxyethylene) (PEO) side chains were synthesized following two distinct pathways. The first route consists in the direct stepgrowth polymerization through addition in water of an equimolar amount of α-(2-aminoethyl)-ω-methoxypoly(oxyethylene) (6) of well-defined molecular weight to 1,4-bis(acryloyl)-piperazine (7) . Furthermore, this reaction was performed in the presence of an excess of the bisacrylmonomer 7 , resulting in a new bisacrylic macromonomer (9) of PEO. In the second route this bisadduc 9 was then polymerized with piperazine (10) , yielding a PEO-grafted PAA. The structures of both polymers were characterized by means of ¹H NMR. Viscosity and vapour pressure osmometric measurements revealed that the molecular weights in both cases were fairly low (M?_n ≈ 3 000).     

Liquid-crystalline polyurethanes, 6. Amphiphilic polyurethanes containing long alkyl chains in the side chains and amino or quaternary ammonium groups in the main chains

Amphiphilic polyurethanes 5a – c , 6a – c , 10a – c and 11a – c containing hydrophilic amino or quaternary ammonium groups in the main chain, and hydrophobic ocatadecyl or docosyl groups in the side chain, were synthesized by polycondensation of 2,2′-octadecyliminodiethanol ( 3a ), 2,2′-docosyliminodiethanol ( 3b ), bis(2-hydroxyethyl)methyloctadecylammonium bromide ( 8 ) and bis(2-hydroxyethyl)docosylmethylammonium bromide ( 9 ) with a diisocyanate such a hexamethylene diisocyanate ( 4a ), 2,4-toluylene diisocyanate ( 4b ) and 4,4′-methylenediphenyl isocyanate ( 4c ). Some of them show a thermotropic liquid-crystalline state, as determined by DSC and polarizing microscopy.     

Synthesis an characterization of polyanhydrides containing amido groups

4,4′-Alkane- and oxaalkanedioyldiiminodibenzoic acids ( 3a–e ) were prepared from 4-aminobenzoic acid and various alkanedioyl and oxaalkanedioyl chlorides ( 2a–e ). A series of polyanhydrides having both hydrolytically labile anhydride linkages and anilide units ( 4a–k ) was prepared by polycondensation of the diacids 3a–k at 150–170°C via acetic mixed anhydrides, using different methods. Molecular weights, glass transition temperatures, and solubilities of the polyanhydrides were found to be dependent upon the reaction conditions and the structure of the monomers used. The highest molecular weight (M _n = 12400) was obtained by thermal polycondensation of isolated acetic mixed anhydride prepolymers formed on the reaction of the diacids 3b, 3c , and 3i with acetic anhydride.     

Synthesis of comb-like methacryl polymers containing condensates of 11-aminoundecanoic- and 6-aminocaproic acid in the side chains

The synthesis and free-radical polymerization of four methacrylic macromonomers, methyl 6-(6-methacryloylaminohexanoylamino)hexanoate ( 5 ), methyl 11-(11-methacryloylaminoundecanoylamino)undecanoate ( 6 ), and the corresponding acids 7 and 8 , are described. The polymers were characterized by DSC and TG analysis. Viscosity measurements show that the polymers tend to associate because of hydrogen bonding. Additionally, incompatibility of the polymers with polyamide-6 was found by DSC measurements.     

Synthesis and characterization of biaxial nematic side chain polymers with laterally attached mesogenic groups

The synthesis and characterization of liquid crystalline side chain polymers with mesogenic groups laterally attached to the polymer main chain are described. By variation of the terminal group, mesogenic moiety or spacer length, a change in the glass transition temperature, the nematic to isotropic transformation temperature and the stability of the nematic phase can be achieved. With increasing length of terminal groups, a distinct odd-even effect of the nematic to isotropic phase transformation temperature and also a strong decrease of the glass transition temperature is observed. Macroscopic homeotropic alignment can be achieved in an electric or magnetic field. Conoscopic investigations show optical biaxial behavior of the nematic phase. A chiral nematic copolymer is the first example of a thermotropic biaxial cholesteric phase.     

Enzymatic cleavage of side chains of synthetic water-soluble polymers

Water-soluble copolymers based on poly[N-(2-hydroxypropyl)methacrylamide] and bearing in their side chains a chromogenic substrate for chymotrypsin were prepared by direct copolymerization or polymeranalogous reaction. The substrate was L -phenylalanine-4′-nitroanilide linked by its amino group to the terminal carboxylic group of the side chain. The cleavage of the substrate thus bonded, was expressed by means of the Michaelis constant, the maximum velocity, and the percentage of substrate unit accesible to the enzyme. The effect of length and chemical structure of the side chain was investigated in the first place. It was found that the chain must be longer than 6 atoms; longer chains are generally more favourable for this cleavage. The ε-aminocaproyl group provides a chain that is most favourable for the cleavage, whereas chains with several glycyl units, though longer, are less favourable. Polymers with higher content of the substrate units undergo cleavage more readily.     

Enzymes in polymer chemistry, 6. Lipase-catalyzed acylation of comb-like methacrylic polymers containing OH groups in the side chains

The enzymatically catalyzed acylation of poly[N-(2-hydroxypropyl)-11-methacryloylaminoundecanamide-co-styrene] and the corresponding monomer was performed in the presence of a lipase, with vinyl acetate, phenyl acetate, 4-fluorophenyl acetate and phenyl stearate as acylating agents. The kinetics of the enzymatically catalyzed reaction was followed by ¹H NMR spectroscopy and correlated with sterical and chemical effects. The reactivity of monomer towards acylation is higher than that of the copolymer, and that of the copolymer depends on copolymer composition, pointing at steric and hydrophobic effects.     

Synthesis and side-chain crystallization of comb-like polymers obtained from isopropenyl-1,3,5-triazines carrying two,three, and four long alkyl groups

Monomers containing several octadecyl groups, e.g., 2-isopropenyl-4,6-bis(octadecylamino)-1,3,5-triazine ( 2 ), 2-dioctadecylamino-4-isopropenyl-6-octadecylamino-1,3,5-triazine ( 3 ) and 2,4-bis(dioctadecylamino)-6-isopropenly-1,3,5-triazine ( 4 ) were prepared by the alkylation reaction of 2,4-diamino-6-isopropenyl-1,3,5-triazine ( 1 ) with 1-bromooctadecane in the presence of sodium hydride. In the free-radical homopolymerization of these monomers, the polymer yield of 3 was lower than that of 2 due to a decrease in the ceiling temperature, and the polymerization of 4 did not proceed. Copolymerizations of these monomers with styrene or methyl methacrylate were carried out and the monomer reactivity ratios (r₁ and r₂) were determined. The monomer reactivity decreased with increasing the number of octadecyl groups in the monomers. Crystallinity of the octadecyl side chains in the resulting comb-like polymers was evaluated by differential scanning calorimetry.     

Reversible crosslinking-decrosslinking of polymers having bicyclo orthoester moieties in the side chains

Radical polymerizations of methacrylate- and styrene-based bicyclo orthoesters (BOEs), and their copolymerization with methyl methacrylate and styrene were carried out with 2,2′-azoisobutyronitrile (AIBN, 5 mol-%) as an initiator in N,N-dimethylformamide (DMF, 2 M ) at 70°C for 15 h to afford the corresponding polymers in 64–96% yields having BOE moieties in the side chains. Crosslinking of the polymers was carried out in the presence of BF₃·OEt₂ (3 mol-%) as a cationic catalyst in CH₂Cl₂. The yield of the crosslinked polymer increased with increasing initial concentration of the polymer and increasing crosslinking temperature. Decrosslinking of the crosslinked polymers was carried out in the presence of trifluoroacetic acid (TFA, 5 mol-%) as a cationic catalyst in CH₂Cl₂ to regenerate the starting linear polymers. The recovery of the starting linear polymer increased with decreasing concentration of the initially crosslinked polymer and with increasing decrosslinking temperature.     

Synthesis and antithrombogenicity of polyetherurethaneurea containing quaternary ammonium groups in the side chains and of the polymer/heparin complex

Novel polyetherurethaneureas containing tertiary amino groups in the side chains (PAEUU) were synthesized, quaternized with different alkyl halides (Q-PAEUU), and heparinized (H-PAEUU). The antithrombogenicity of PAEUU in vitro was improved by quaternization, and further by heparinization. The excellent antithrombogenicity of H-PAEUU was controlled by the kind of quaternizing agent through the polar effect of quaternizing agent on the water content and through the steric effect of quaternizing agent on the heparin content of H-PAEUU. The antithrombogenicity of H-PAEUU was found to be affected by the water content more strongly than by the heparin content. H-PAEUUs containing tertiary amino groups in the main chain, which were synthesized previously, showed a little better short-term antithrombogenicity than the present H-PAEUUs containing tertiary amino groups in the side chains. Since ammonium groups in the side chains of Q-PAEUU impose little steric hindrance against the heparin adsorption, the release of heparin from the side chains of H-PAEUU was slower but lasted longer than that from the main chain. Therefore, the present H-PAEUU is expected to be a long-term antithrombogenic material.     

Enzymatic splitting of side chains in soluble polymers. The effect of length and structure of the side chain

A series of soluble polymers was prepared by copolymerization of the 4-nitrophenol ester of N-methacryloylated ω-amino acids ( 1a – i ), of N-methacryloyldiglycine ( 2b ), of 6-(N-methacryloylglycylamino)- and of 6-(N-methacryloylglycylglycylamino)hexanoic acid ( 3a and 3b ) with N-(2-hydroxypropyl)methacrylamide (HPMA). The resulting polymers contained roughly 3 mol-% of nitrophenol groups. Polymeranalogous reaction with 4′-nitro L-phenylalanineanilide ( 4a ) or with its N-glycyl and N-glycylglycyl derivates ( 4b and 4c ), yielded polymers which at the end of their side chain of various length and structure had a bond degradable with chymotrypsin. The rate of enzymatic hydrolysis was investigated as a function of the length and structure of side chain. It was found that in copolymers possessing side chains formed by ω-amino acid residues, the rate of hydrolysis increases with increasing length of the side chain. The rate of cleavage of the peptide bond has a maximum value for a spacer that possesses six methylene groups. With increasing length of the side chain the rate of hydrolysis again decreases. A similar dependence was observed for side chains formed by dipeptides of ω-amino acids and glycine. In copolymers with oligoglycine side chains, the rate of enzymatic hydrolysis also increases with increasing length of side chain. In other types of side chains formed by combination of hydrophobic and hydrophilic segments, a number of factors become operative which affect the rate of enzymatic hydrolysis and are very difficult to specify.     

Vinyl polymers containing amido and carboxyl groups as side substituents, 2. Thermodynamic and fourier-transform infrared spectroscopic studies for the protonation of poly(N-acryloylglycine) and poly(N-acryloyl-6-aminocaproic acid)

Synthetic poly(N-acryloylglycine) (poly[1-(carboxymethylcarbamoyl)ethylene], 1a ) and poly-(N-acryloyl-6-aminocaproic acid) (poly{1-[5-(carboxypentyl)carbamoyl]ethylene}, 1b ) were studied in aqueous solution by thermodynamic (potentiometry, calorimetry) and Fouriertransform infrared (FT-IR) spectroscopic methods. The values of the basicity constant (log K), calculated with the Henderson-Hasselbalch equation, relative to the protonation of the carboxylate group, decreases with increasing degree of protonation (a), while the enthalpy changes are “real” for both polymers. The increased length of the lateral aliphatic chain causes a decrease in the polyelectrolyte effect and a greater entropy change ΔS° of protonation due to liberation of water molecules. At low pH the FT-IR spectra reveal a strong band at 1 628 cm^?1 for polymer 1b which does not occur in the spectra of polymer 1a . At this pH the more compact macromolecular structure of 1b may favour interactions among the amido groups of several monomeric units.