Presence Of Poly Methacrylate Research Articles

Crosslinking polymerization leading to interpenetrating polymer network formation. 3. Polyaddition crosslinking reaction of poly(methyl methacrylate-co-2-methacryloyloxyethyl isocyanate) with poly(oxytetramethylene) glycol in the presence of linear polymethacrylate resulting in semi-interpenetrating polymer network

As part of a series of our works concerned with the elucidation of the crosslinking polymerization mechanism leading to the interpenetrating polymer network (IPN) formation, in which IPN consists of both polyurethane (PU) and polymethacrylate (PM) networks, this article deals with the polyaddition crosslinking reactions of poly(methyl methacrylate-co-2-methacryloyloxyethyl isocyanate) poly(MMA-co-MOI) [MMA/MOI = 99/1] as a novel multifunctional polyisocyanate with poly(oxytetramethylene) glycol [H-(OCH2CH2CH2CH2)n-OH (n = 28)] (POTMG-28) in the presence of two types of linear PMs, differently miscible with the resulting PU networks, leading to semi-IPN formation. Thus, poly(MMA-co-MOI) was prepared by the radical copolymerization of MOI with MMA in the presence of CBr4 as a chain-transfer agent. No influence of the linear PM on the rate of polyaddition crosslinking reaction was observed. The actual gel points were compared with the theoretical ones calculated according to Macosko's equation: the deviation of the actual gel point from the theoretical one was rather small, close to the ideality, and the delayed gelation from theory tended to become a little smaller in the presence of PM. These are discussed mechanistically to deepen the understanding of the PU network formation in the presence of a linear PM resulting in semi-IPN, along with the data of the intrinsic viscosities of resulting prepolymers. To collect a direct evidence of semi-IPN formation, we attempted to pursue the incorporation of the linear PM into the resulting PU networks by 1H-NMR and UV-vis spectroscopy; in the latter case, the copolymers containing a small amount of pyrenyl methacrylate were used as linear PMs because the pyrenyl group was employed as the probe for UV-vis spectroscopic determination of the amount of the incorporated PM. The swelling ratio of the gel became lower in the presence of a linear PM. All data for the polyaddition crosslinking reactions of poly(MMA-co-MOI) with POTMG-28 in the presence of PM, along with the mechanistic discussion, demonstrate that the freely compatible molecular interaction would lead to a true semi-IPN formation as a result of the good miscibility between PU networks and a linear PM. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1198–1208, 2004

Voltammetry of MnII and CoII in the presence of polymethacrylate

AbstractComplex formation of MnII and CoII with polymethacrylic acid (PMA) is studied by differential pulse polarography, normal pulse polarography, reverse pulse polarography, cyclic voltammetry and differential pulse anodic stripping voltammetry. Because of the lack of a model for macromolecular metal systems including Mn+/M(Hg) couples with irreversible electrochemical behavior, the application of the theoretical model developed for reversible electrochemical systems is tested to the slow MnII/Mn(Hg) and CoII/Co(Hg) couples. The quality of the experimental results obtained allows us to calculate the formation constants of the predominating MnII/PMA and CoII/PMA complexes and also their dependence on complexation variables.

“Activator-competitive” enzyme inhibition. Interrelation of dissociation, activation, inhibition and surface inactivation of β-glucuronidase

1. 1. Dilution of β-glucuronidase causes reversible dissociation of the enzyme into inactive polypeptides. 2. 2. Many polycations are able to prevent the dissociation and, thus, act as activators of the diluted enzyme. 3. 3. Polymethacrylic acid and polystyrene sulfonate reversibly inhibit dilute β-glucuronidase by sequestering its activator with which they form complexes. Enzyme and inhibitor compete with each other for the activator. The potency of the inhibition depends on the chemical nature of the activator and on its concentration, a mechanism which results in an antagonism between inhibitor and activator. 4. 4. The products of dissociation of β-glucuronidase are irreversibly altered upon contact with rough surfaces, such as scratched glass or quartz sand, inasmuch as the addition of activators no longer restores the original enzyme activity. Thus, handling of diluted β-glucuronidase in ordinary glassware causes an irreversible inactivation. 5. 5. The inactivation can be prevented by the presence of activators during the contact with glass, or it can be boosted by the presence of polymethacrylate or polystyrene sulfonate. Concentrated enzyme solutions are stable in glass, and diluted enzyme solutions are not inactivated in polyethylene containers.