Versatile Mechanical and Thermoresponsive Properties of Macroporous Copolymer Gels

Abstract

Random copolymer gels of N‐isopropylacrylamide (NIPAM) and N‐ethylacrylamide (NEAM) are synthesized using different monomer compositions in 1:1 methanol–water mixtures. The samples are characterized by scanning electron microscopy, atomic force microscopy (AFM), and rheological studies. It is observed that with the variation of the monomer compositions in the reaction mixture, the thermoresponsive, morphological, AFM, and rheological properties varied significantly. Porosity and roughness of the gels gradually increase with the gradual increase in NIPAM loading in the gels, lower critical solution temperature, mechanical strength (Young's modulus, storage modulus) significantly decreases with the increase in poly(N‐isopropylacrylamide) loading in the gels. All results can be explained on the basis of the differences in thermoresponsive character of homo‐ and copolymer gels of NIPAM and NEAM in water, their composition in the reaction mixtures, and their different kind of interactions with solvents.

Reduced graphene oxide composites with water soluble copolymers having tailored lower critical solution temperatures and unique tube-like structure

“…2b ). For PNIPAM, the expected LCST around 32 °C was found, while PNEAM’s LCST was found to be between 68 and 82 °C 42 43 . The copolymers’ LCST varied systematically monomer composition dependent and almost linearly between these two ( Fig.…”

Hydrogen Bonds in Blends of Poly(N-isopropylacrylamide), Poly(N-ethylacrylamide) Homopolymers, and Carboxymethyl Cellulose

“…Higher contents of ions induce a lower phase transition temperature [11]. Furthermore, the LCST is very similar independently of the ratio of pNIPAM and pNEAM, which is a clear indicator of the independence between different polymeric chains, as for a random-copolymer, the LCST-temperatures would vary systematically with comonomer content [17,37,45,46].…”

“…The transition placed at a lower temperature can be identified as the LCST of pNIPAM because the LCST related to pNIPAM is defined at around 32 • C [33,34]. On the other hand, the second LCST placed at higher temperatures is associated with pNEAM, whose values were previously found to be between 62 and 82 • C depending on the measurement method and molar mass [35][36][37]. Both LCSTs can be identified for all mixtures with the transmission between the LCSTs scaling with the mixing proportion.…”

“…The samples performed in methanol and water (Figure 3) exhibit unusual as the first LCST (associated with pNIPAM-chains), cannot be observed. The vency could explain this effect because pNIPAM shows no or only a weak LCS tures of methanol and water (1:1) once the methanol content exceeds [17,37,45,46,48]. This fact could be attributed to the hydrophobic behavior of the polymeric chains.…”

Sorption and desorption properties of random copolymer hydrogels of N‐isopropylacrylamide and N‐ethylacrylamide: Effect of monomer composition

“…Recently we published an article on AFM study of PNIPAM gels synthesized in different methanol‐water mixtures . Very recently, we published an article on the mechanical properties of random copolymer gels of PNIPAM and PNEAM by varying the monomer compositions, whilst keeping solvent composition (1:1 methanol‐water mixture) fixed; and another one based on the physical properties of random copolymer gels of PNIPAM and PNEAM by varying the solvent compositions and keeping monomer compositions constant …”