Poly Methacrylamide Research Articles

Adsorption of water‐soluble, nonionic polymers onto cellulosic fibers

AbstractThe adsorption of 12 different nonionic water‐soluble polymers, methylcellulose (MC), hydroxypropylcellulose (HPC), polygalactomannan (PGM), polyglycidol (PGD), polyacrylamide (PAAm), methylolated polyacrylamide (MPAAm), polymethacrylamide (PMAAm), three differently hydrolyzed poly(vinyl acetate)s (PVAs), poly(vinyl) methyl ether (PVME), and poly(vinyl pyrrolidone) (PVP) onto bleached kraft pulp (BK), unbleached kraft pulp (UK), and a groundwood pulp (MP) has been investigated under aqueous conditions with attention to the functional groups in the polymers and the chemical character of the pulps. It was found that the adsorption was often selective toward one of the pulps. In order to gain some additional information on these interactions, some adsorption experiments were also performed on acetylated pulps. Some polymers (PGD, PAAm, MPAAm, and PVA 124) having both proton donating and accepting capability were not adsorbed onto any of the pulps. This was attributed to intramolecular hydrogen bonding in these polymers. Some polymers (PVA 224, PVME, and PVP) were strongly adsorbed onto UK but not at all onto BK. It was suggested that in these cases the adsorptive interaction was between phenolic and/or catecholic groups in the lignin on the UK and proton accepting sites on the polymers. However, for three polymers (MC, PGM, and PMAAm), a more general type of hydrogen bonding interaction was considered. For some polymers (HPC, PMAAm, and PVA 420) having hydrophobic groups, it was suggested that hydrophobic interactions were important for the adsorption.

Entrapment of living microbial cells in covalent polymeric networks: I. Preparation and properties of different networks

Different procedures for the formation of polymeric networks to be applied in whole cell entrapment for the preparation of biocatalysts are outlined and compared. These methods include suspension polymerization of water soluble monomers (acrylamide, methacrylamide), water insoluble monomers (methylmethacrylate), and polycondensation of urea and formaldehyde. Special emphasis is given to the detailed description of possible variations in polymer composition and polymerization conditions in relation to the catalytic and mechanical properties of the biocatalyst preparations. The mechanical properties of polymethacry lamide networks can be shown to be significantly improved if compared to conventional polyacrylamide preparations.

The thermal degradation of polymethacrylamide and copolymers of methacrylamide and methyl methacrylate

Thermal analysis demonstrates that the thermal degradation of polymethacrylamide (PMAM) occurs in two well defined steps. The only volatile products formed in the first step, below 340, are ammonia and water while imide replaces amide absorption in the infra-red spectrum of the residue. Above 340° the major product consists of chain fragments (approximately 50%) in which a high proportion of the amide groups have been converted to cyclic imides. Copolymers with methyl methacrylate (MMA) comprising more than 35% methacrylamide (MAM) also degrade in two similar steps but the overall behaviour becomes progressively more like that of polymethylmethacrylate as the MAM content is decreased below 10%. In the first stage of the reaction in the copolymer, MMA and methanol are important products in addition to ammonia and water. Chain fragments remain the major product in the second stage but a number of minor, but very significant, products are also formed. All these products and the structural features of the chain fragments and residue have been accounted for mechanistically.

THE INTERACTIONS OF POLYACRYLIC ACID, POLYMETHACRYLIC ACID, POLYACRYLAMIDE AND POLYMETHACRYLAMIDE WITH SOME DISPERSE DYES

The interactions of polyacrylic acid (PAA), polymethacrylic acid (PMA), polyacrylamide (PAAm) and polymethacrylamide (PMAm) with some disperse dyes such as azobenzene, p-hydroxyazobenzene and p-aminoazobenzene were studied by an equilibrium dialysis method at 5°, 15° and 25°C.It was found that PMA displays a strong binding affinity toward these disperse dyes and on the contrary PMAm does a weak one. In the cases of PAA and PAAm no similar phenomena were observed. An addition of urea to PMA solution promoted a marked decrease in the binding ability.The results are interpreted in terms of the interaction of these dyes with partially hydrophobic tightly coiled chains of PMA, which are stable in aqueous solution and not in aqueous urea solution.The binding isotherm between the dyes and PMA was exhibited by the Langmuir one, so the thermodynamic parameters, free energy change, enthalpy change and unitary entropy change, can be calculated from the Klotz's equation. The free energy change and the enthalpy change obtained in this work are all negative and the unitary entropy change is large positive. The favorable binding process, therefore, involves two main contributions, an entropy gain and an exothermic interaction. Comparing the effect of the entropy term with that of the enthalpy one, the former is larger than the latter in the course of the binding process. In particular azobenzene which is the least polar compound has larger positive entropy change.From the above data it was deduced that the large positive unitary entropy change may be attributed to the hydrophobic interaction between the dyes and PMA.The viscosity of PMA, PAA, PAAm and PMAm in aqueous solution and aqueous urea solution was measured and discussed in some detal.

Alkaline and acid hydrolysis of polyvinylamides

AbstractThe alkaline and acid hydrolyses of polyvinylamides and their N‐substitution derivatives have been studied and compared to the alkaline and acid hydrolyses of simple homologous substances. The rates of reaction have been followed conductometrically, and the rate constants evaluated at different temperatures in order to determine the energies of activation and the log PZ of the Arrhenius equation. The influence of the polymeric structure on the course of the reactions has been shown. In alkaline medium the increasing negative charges on the polymeric chain exert an electrostatic repulsion effect toward the hydroxyl ion, and, as a consequence, cause a progressive decrease of the rate of reaction. In the case of polyacrylamide (PAA), hydrolysis enhances an uncoiling of the polymeric chain when the degree of conversion reaches about 40%. Therefore the reaction is characterized by two different steps, a first, rapid step analogous to the reaction of aliphatic monoamides (Ea = 13.7 kcal.), and a second, slow step related to the increasing electrostatic effect. This interpretation has been confirmed by hydrolysis measurements on copolymers of acrylamide‐vinylpyrrolidone (42/58) and acrylamide‐acrylic acid (64/36). In the case of polymethacrylamide (PMA), N‐methyl‐PAA, and N,N′‐diethyl‐PAA steric hindrance along the chains confers a stretched configuration on the macromolecules, and reinforces the electrostatic effects; therefore, the rate constants, can be determined only at low degree of conversion. Moreover, the maximum degree of hydrolysis becomes limited and is 72, 55, and 35 for PMA (Ea = 16 kcal.), N‐methyl‐PAA (Ea = 18.3), and N,N′‐diethyl‐PAA (Ea = 22 kcal.), respectively. N,N′‐Diethylpolymethacryamide is completely alkali‐resistant. In acidic medium the hydrolysis of PAA and PMA is characterized by a secondary intramolecular cyclization due to imide formation between amide and acid functional groups. This secondary reaction, which becomes appreciable at 85°C., causes an increase in the overall energy of activation of the hydrolysis, which is consequently 3 to 4 kcal. higher than those of aliphatic low molecular weight compounds. On the other hand, this imidization is absent in the case of the N‐substituted polymers, of which the energies of activation are equal to those of the aliphatic homologous substances (N‐methyl‐PAA = 21.7; N,N′‐diethyl‐PAA = 24.6 kcal.).