Catalog NumberHG-BULK25067612
CAS Number25067-61-2
CategoryPolymers
Polymethacrylonitrile as Crosslinking Precursor for Superabsorbent Drug Delivery Hydrogels
Sadeghi, M., et al. (2013). Asian Journal of Chemistry, 25, 4847-4850.
Polymethacrylonitrile (PMAN) served as a macromolecular precursor that, upon alkaline hydrolysis in the presence of pectin, formed a three-dimensional superabsorbent hydrogel network suitable for pH-responsive drug delivery. The nitrile groups of PMAN underwent in situ crosslinking with pectin alkoxide ions and subsequent hydrolysis to generate hydrophilic carboxamide and carboxylate functionalities.
Experimental Protocol: Pectin (0.50-1.33 g) was dissolved in 35 mL of doubly distilled water in a three-neck reactor with mechanical stirring. Sodium hydroxide solution (0.25-2.5 N) was added at temperatures ranging from 20 to 120 C to convert pectin hydroxyls to alkoxide ions. PMAN (0.50-4.50 g) was then dispersed into the mixture and saponified for controlled times and temperatures. A sharp color change from red to light yellow, accompanied by NH3 gas evolution, signaled reaction completion. The pasty mixture was cooled, neutralized to pH 8 with 10 wt% acetic acid, dewatered in ethanol, and dried at 50 C for 10 h.
Performance Evaluation: FTIR spectroscopy confirmed conversion of the nitrile group (2242 cm-1) to carboxamide (1675 cm-1) and carboxylate (1556 and 1407 cm-1) functional groups. SEM imaging revealed a highly porous microstructure conducive to water permeation. TGA indicated improved thermal stability of the grafted hydrogel compared to native pectin, with 79% residual weight retained at 325 C. Swelling capacity varied strongly with pH, reaching a maximum of approximately 95 g/g at pH 7.4 due to ionic repulsion among ionized carboxylate groups, while shrinking at pH 1.6. The hydrogel exhibited reproducible, reversible pulsatile swelling-deswelling behavior when cycled between pH 7.4 and pH 1.6 at 30-minute intervals.
Polymethacrylonitrile as Well-Defined omega-Vinylidene Macromonomer for Controlled Radical Polymerization
Yamago, S., et al. (2009). Reactive and Functional Polymers, 69, 416-423.
Polymethacrylonitrile was synthesized with precisely controlled omega-vinylidene end-group functionality via organobismuthine-mediated living radical polymerization (BIRP), enabling the production of structurally well-defined macromonomers with narrow molecular weight distributions and predictable thermal degradation profiles.
Experimental Protocol: Methacrylonitrile (3.0 mmol) and methyl 2-dimethylbismuthanyl-2-methylpropionate (0.10 mmol) as the organobismuthine initiator were heated in DMF (1.0 mL) at 80 C with stirring for 3 h under nitrogen atmosphere. Monomer conversion of 91% was confirmed by 1H NMR, yielding polymethacrylonitrile with Mn of 3300 and PDI of 1.23. TEMPO (0.30 mmol, 3 equiv) was then added and the mixture was heated at 100 C for 2 h to effect quantitative omega-end-group transformation from the organobismuthine terminus to the omega-vinylidene group. Residual monomer and solvent were removed under reduced pressure, and the product was purified by precipitation from acetone into hexane.
Performance Evaluation: 1H NMR analysis in DMF-d7 revealed characteristic olefinic signals at 6.24-6.34 and 6.38-6.46 ppm, and comparison of these integrals with those of the alpha-polymer-end methyl ester and chain methylene protons indicated 92% efficiency of the omega-end group transformation. The final omega-vinylidene polymethacrylonitrile was obtained in 92% yield with Mn of 3200 and narrow PDI of 1.23. TGA analysis demonstrated clean one-step thermal degradation, reflecting the defined end-group structure, with degradation behavior substantially different from that of omega-hydrogenated PMMA analogues and consistent with the high end-group fidelity achieved through the BIRP-TEMPO methodology.