Microstructural analysis of p -acryloyloxy-acetanilide and N , N -dimethylacrylamide copolymers of biomedical interest by NMR

Bulai, A. Kh.; Queiroz, Alvaro-Antonio Alencar de; Gallardo, Alberto; Román, Julio San

doi:10.1016/s0032-3861(98)00710-1

Cited by 6 publications

(5 citation statements)

References 22 publications

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“…The distribution of protons in the two units is an important means of distinguishing monomers, VP and DMAM, in the copolymer chain. In the VP–DMAM copolymers, the >N(CH 3 ) 2 group protons of DMAm and CH 2 and the CH group protons of VP are distinguishable 38, 39. Hence, in the present study, the distinct peaks of >N(CH 3 ) 2 protons (Fig.…”

Section: Resultssupporting

confidence: 51%

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Lactam–amide graft copolymers as novel support for enzyme immobilization

Queiroz

Vargas

Higa

et al. 2002

J of Applied Polymer Sci

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A graft random copolymer of N-vinyl-2-pyrrolidone and N,NЈ-dimethylacrylamide onto polypropylene was synthesized using a simultaneous gamma radiation technique from a 60 Co source, so that the hydrogel poly(propylene-g-vinylpyrrolidone-, thus produced by grafting, could be used as a support for enzyme immobilization. The grafted spheres showed very good swelling behavior in water due to the incorporation of hydrophilicity in the PP spheres. The influence of pH and temperature on as well as the determination of the kinetic parameters, K M and V max , for both immobilized and soluble invertase were determined. PP-g-(VP-co-DMAM) grafting onto the PP spheres caused a significant change in the water content of the support and was more pronounced for the spheres with a high degree of grafting. A porous structure of the polymeric spheres was observed by scanning electron microscopy (SEM). The porous structure contributed to the reaction rate decrease due to diffusional effects, as shown by the larger K M value observed for immobilized invertase relative to the free enzyme. The enzyme affinity for the substrate (K M /V max ) remains quite good after immobilization. The thermal stability of immobilized invertase was significatively higher than that of the free enzyme and a displacement of 20°C was observed for the immobilized enzyme.

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Section: Resultssupporting

confidence: 51%

“…In the VP-DMAM copolymers, the ϾN(CH 3 ) 2 group protons of DMAm and CH 2 and the CH group protons of VP are distinguishable. 38,39 Hence, in the present study, the distinct peaks of ϾN(CH 3 ) 2 protons (Fig. 3) are chosen for the estimation of the DMAM composition in the copolymer.…”

Section: Resultsmentioning

confidence: 99%

Lactam–amide graft copolymers as novel support for enzyme immobilization

Queiroz

Vargas

Higa

et al. 2002

J of Applied Polymer Sci

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“…We do not know the reactivity ratios of the comonomers, and the microstructure of the polymer chains is difficult to establish by 13 C NMR due to the complexity of the DMA signals. − Nevertheless, an analogy with the pair acrylamide/acrylic acid may be drawn. In this case, the reactivity ratios are strongly pH dependent: r acrylamide = 1.32 and r acrylic acid = 0.35 in basic conditions .…”

Section: Resultsmentioning

confidence: 99%

“…[28][29][30] Nevertheless, an analogy with the pair acrylamide/acrylic acid may be drawn. In this case, the reactivity ratios are strongly pH dependent: r acrylamide ) 1.32 and r acrylic acid ) 0.35 in basic conditions.…”

Section: Precursor Synthesismentioning

confidence: 99%

Control of the Reversible Shear-Induced Gelation of Amphiphilic Polymers through Their Chemical Structure

et al. 2004

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This paper reports on the synthesis and characterization of a series of amphiphilic polymers which exhibit spectacular reversible shear-induced gelation in water. The systems consist of hydrophobically modified copolymers based on N,N-dimethylacrylamide and acrylic acid. The influence of molecular parameters such as the molecular weight and composition of the terpolymers on the rheological properties has been established. In the linear regime, the polymers behave like classical associating polymers: the sharp increase of the viscosity with concentration is the result of the transformation of intra-into intermolecular associations. Moreover, the dynamics of the physical gels obtained at high concentrations is tremendously slowed by the presence of alkyl side chains. Under shear the solutions display a Newtonian plateau at low shear rate followed by a shear-induced gelation. The latter is characterized in terms of a critical shear rate which sharply decreases as the polymer volume fraction increases. Thus, it appears that the shear-induced gelation may be controlled by adjusting the polymer molecular features. The networks built under shear closely behave like highly concentrated solutions at rest, suggesting a possible parallel between increasing shear and increasing concentration. This latter fact is reminiscent of the situation encountered with wormlike micelles. Shear flow could induce a transition between individual aggregates and a transient network as an increase in concentration does, thanks to the sharp modification of the electrostatic screening at the overlap concentration.

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“…Random copolymers of N-vinyl-2-pyrrolidone (VP) and N,N-dimethylacrylamide (DMAm) were prepared and characterised according to the method described in our previous publication [41]. Brie#y, copolymerisation reactions between VP and DMAm were carried out under vacuum in ethanol as the solvent using azobis(isobutyronitrile) (AIBN) (1.5;10\ mol/l) as initiator, at 503C.…”

Section: Copolymers Synthesismentioning

confidence: 99%