1,721,038 research outputs found
New basic multifunctional polymers. III. Synthesis and properties of poly(amidothioetheramine)s (
No full textEight poly(amidothioetheramine)s have been synthesized by polyaddition reaction of 2,2′-alkylene- diiminodiethanethiols to N,N′-methylene- bisacrylamide and 1,4-bisacryloylpiperazine, respectively. These polymers have been fully characterized
Evaluation of adsorbing capacity and selectivity of a new ion exchange resin with a poly(amido-amine) structure
No full textEnd-functionalised 1-vinyl-2-pyrrolidinone oligomers bearing lactate functions at one end
No full text1-Vinyl-2-pyrrolidinone (VP) oligomers bearing a lactate group at one end (PVP-L) were obtained by chain-transfer controlled radical polymerisation carried out in the presence of ethyl L-lactate as chain-transfer agent (CTA). Their number-average molecular weights were in the range 1500-4000 with molecular weight distributions ranging from 1.4 to 1.8. The chain transfer constant, C-T, of the ethyl L-lactate/VP system was determined by monitoring the variation of PVP-L number-average molecular weight on conversion. The C-T value so obtained was 1.03 x 10(-2) which is by about one order of magnitude higher than the CT value previously determined for a seemingly similar system, namely methyl isobutyrate/1-vinyl-2-pyrrolidinone (1.64 x 10(-3)). The resultant PVP-L oligomers were thoroughly characterised by means of H-1 and C-13 NMR, in order to ascertain the regular presence of the lactate functions at one of their chain terminals. NMR characterisations gave results in full agreement with the proposed structure. Moreover, the molecular weight values determined by NMR very closely agreed with those obtained by SEC. Preliminary biological evaluations of the PVP-L oligomers showed a complete lack of toxicity
The Mannich bases in polymer synthesis 3. Reduction of poly(b-aminoketone)s to poly(g-aminoalcohol)s and their N-alkylation to poly(g-hydroxy quaternary ammonium salt
No full textSeveral poly(β-aminoketone)s, obtained by polyconensation of bis Mannich bases with bis (secondaryamine)s, have been quantitatively reduced to poly(γ-aminoalcohol)s. The stereochemistry of these polymers, as well as that of the reduction products of the parent bis Mannich bases has been investigated. By N-alkylation of the same polymers, poly(γ-hydroxy quaternary ammonium salt)s have been also prepared. © 1982
Applied macroinorganics. IV. Effect of the crosslinking agent on protonation and metal ions complexing abilities of ion exchange resins with poly(amido-amine) structure
No full textNovel poly(amido-amine)-based hydrogels as scaffolds for tissue engineering
No full textBiodegradable and biocompatible amphoteric poly(amido-amine) (PAA)-based hydrogels, containing carboxyl groups along with amino groups in their repeating unit, were considered as scaffolds for tissue engineering applications. These hydrogels were obtained by co-polymerising 2,2-bisacrylamidoacetic acid with 2-methylpiperazine with or without the addition of different mono-acrylamides as modifiers, and in the presence of primary bis-amines as cross-linking agents. Hybrid PAA/albumin hydrogels were also prepared. The polymerisation reaction was a Michael-type polyaddition carried out in aqueous media. The PAA hydrogels were soft and swellable materials. Cytotoxicity tests were carried out by the direct contact method with fibroblast cell lines on the hydrogels both in their native state (that is, as free bases) and as salts with acids of different strength, namely hydrochloric, sulfuric, acetic and lactic acid. This was done in order to ascertain whether counterion-specific differences in cytotoxicity existed. It was found that all the amphoteric PAA hydrogels considered were cytobiocompatible both as free bases and salts. Selected hydrogels samples underwent degradation tests under controlled conditions simulating biological environments, i.e. Dulbecco medium at pH 7.4 and 37 degrees C. All samples degraded completely and dissolved within 10 d, with the exception of hybrid PAA/albumin hydrogels that did not dissolve even after eight months. The degradation products of all samples turned to be non-cytotoxic. All these results led us to conclude that PAA-based hydrogels have a definite potential as degradable matrices for biomedical applications
Synergism between α-amino acid-derived polyamidoamines and sodium montmorillonite for enhancing the flame retardancy of cotton fabrics
Full text linkPolyamidoamine (PAA)/sodium montmorillonite (MMT) nanocomposite coatings were investigated as flame retardants for cotton to ascertain whether the addition of clay improved the efficacy of PAAs thanks to its ability to act as insulating shield during combustion. Three amphoteric PAAs were obtained by reacting N,N’-methylenebisacrylamide with natural alfa-amino acids, namely glycine (M-GLY), arginine (M-ARG) and glutamic acid (M-GLU). These PAAs act as intumescent flame retardants for cotton performing well in horizontal flame spread tests (HFSTs) but failing to inhibit combustion in vertical flame spread tests (VFSTs). All three PAAs have been proven to form strong interactions in water with MMT via their protonated tert-amine groups. The presence of 12.5% MMT did not significantly change the thermal and thermo-oxidative stability of PAA coatings, while 2% MMT add-on affected those of both untreated and PAA-treated cotton fabrics. In HFSTs, substituting 2% MMT for PAA did not significantly change the flame retardant efficacy of the coatings. In VFSTs, the 2% MMT/14% PAA combination inhibited cotton ignition, regardless of the PAA structure, while in the 2% MMT/11% PAA combination M-GLU protected cotton from ignition, M-ARG extinguished the flame and M-GLY burned completely. By further reducing the PAA content to 8%, only M-GLU quenched cotton combustion, leaving an RMF of 82%. The fact that neither MMT nor PAAs alone induced flame extinguishment at the same add-ons used in the adopted formulations suggests a synergistic behavior of MMT and PAAs
Applied macroinorganics. II. Protonation and heavy metal ions complex-formation behaviour of three crosslinked resins of poly(amido-amine) structure
No full textThree resins having a poly(amido-amine) structure have been synthesized. The basicity and complexing ability towards copper(II) have been investigated by potentiometric techniques, and compared with those of the corresponding soluble polymers. The adsorbing capacities of the resins in columns were tested and a sharp separation between different metal ions was achieve
Polymers of N-acryloylmorpholine activated at one end and conjugates with bioactive materials and surfaces
No full textPolymers of the monomer N-acryloylmorpholine having a single reactive moiety at one end of the polymer chain have the following structure: ##STR1## wherein --Z--X--Y is a polymer capping moiety, such as mercaptan, X represents a saturated residue of a linear or branched aliphatic series of the general structure --C.sub.r H.sub.2r -- in which r is an integer from 1 to about 12, Y is a reactive moiety and typically will be one of the reactive moieties commonly known in PEG chemistry, such as an --OH, --COOH, or --NH.sub.2 group, Z is a moiety that readily reacts to cap a polymer free radical, and n is an integer from about 6 to 280, which yields a number average molecular weight ("M.sub.n ") of from about 1,000 to 40,000. The monofunctional polymer is a suitable alternative to monofunctional PEG for modification of substances having biological and biotechnical applications
Protonation and complex formation with heavy-metal ions of two tetrafunctional amines and of a new structurally related ion-exchange resin
No full textThe basicity and complexing ability towards copper(II) of two new tetrafunctional amines containing four basic aliphatic nitrogens (1) and two aliphatic and two heterocyclic nitrogens (2) have been investigated by potentiometric techniques. The basicity constants of the two compounds are different which indicates that the mechanism of protonation is different for the two amines. The presence of complexes [Cu(HL)], [CuL], [Cu(OH)L] for L = (1) and [Cu(H2L)], [Cu(HL)], [CuL], and [Cu(OH)L] for L = (2) could be detected in aqueous solution. A resin whose repeating unit is structurally related to (2) has been synthesized, and its basicity and stability constants have been compared with those of compound (2)
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