On the water swelling behaviour of poly(N-isopropylacrylamide) [P(N-iPAAm)], poly(methacrylic acid) [P(MAA)], their random copolymers and sequential interpenetrating polymer networks (IPNs)

The influence of the copolymer composition on the diltiazem hydrochloride release from a series of pH-sensitive poly[(N-isopropylacrylamide)-co-(methacrylic acid)] hydrogels

“…37 However, in its P[(N-iPAAm)-co-(MAA)] copolymers due to the addition of a more hydrophilic monomer MAA to N-iPAAm, which hinders the aggregation of the polymer chains and acts to expand the collapsed structure, the shrinkage at this temperature and pH is suppressed even in those cases in which only small amounts of MAA are present in the copolymer. 25 Copolymers presenting the highest equilibrium of swelling, also exhibited the fastest DIL.HCl release. In Figure 3, DIL.HCl release profiles are displayed for the same series of gels at 37°C and pH 1.2.…”

“…Some other details have been given. 24,25 Copolymer composition (Table 1) was determined by elemental analysis performed using a CHN EA 1108-elemental analyzer (Carlo Erba Instruments, Milano, Italy). Because the previous swelling history was shown to have strong influence on the swelling behavior, 26 samples from synthesis were soaked under acidic medium (pH 1.2) and dried in a vacuum oven at 60°C for 24 hours in order to obtain homogeneous samples with a controlled morphology history.…”

“…25 Analysis of the equilibrium and dynamic swelling characteristics of all hydrogels was performed at 37.0°C ± 0.1°C. For the swelling experiments, buffer solutions were prepared by mixing known amounts of ortho-phosphoric acid, disodium hydrogen phosphate, and potassium dihydrogen phosphate in order to vary the pH, and the ionic strength was kept constant at 0.1 M by using NaCl.…”

“…10,[16][17][18][19][20][21][22][23][24][25][26] These copolymers possess a wide range of swelling characteristics depending on composition and previous swelling history, [24][25][26] which potentially allow hydrogels to be obtained for specific uses. Because of the N-iPAAm moiety, these copolymers are able to respond to temperature changes, while the ionizable carboxyl group provides pH sensitivity.…”

N‐isopropylacrylamide decomposition process in helium plasma

“…1), which has been attracting the attention of many authors in relation to its technological and biomedical applications. [12][13][14] Scientists are working with hydrogels incorporating NIPAAm monomer [15][16][17] because in water solution and hydrogels it shows low critical solution temperature, 18 around 328C, close to the human body temperature. This is the reason why NIPAAm-based gels have been used as drug delivery systems.…”