Synthesis and network parameters of hydrophobic poly(N‐[3‐(dimethylaminopropyl)]methacrylamide‐co‐lauryl acrylate) hydrogels

Abstract

ABSTRACT:Hydrophobic poly(N-[3-(dimethylaminopropyl)]methacrylamide-co-lauryl acrylate) [P(DMAPMA-co-LA)] hydrogels with different LA content were synthesized by free-radical crosslinking copolymerization of corresponding monomers in water by using N, N-methylenebis(acrylamide) as the crosslinker, ammonium persulfate as the initiator, and N,N,NЈ,NЈ-tetramethylethylenediamine as the activator. The swelling equilibrium of the hydrogels was investigated as a function of temperature and hydrophobic comonomer content in pure water. An interesting feature of the swelling behavior of the P(DMAPMA-co-LA) hydrogels with low LA content was the reshrinking phase transition where the hydrogels swell once and collapse as temperature was varied in the range of 30 -40°C. The average molecular mass between crosslinks (M c ) and polymer-solvent interaction parameter () of the hydrogels were calculated from equilibrium swelling values. The enthalpy (⌬H) and entropy (⌬S) changes appearing in the parameter for the hydrogels were determined by using the Flory-Rehner theory based on the phantom network model of swelling equilibrium. The positive values for ⌬H and ⌬S indicated that the hydrogels had a positive temperature-sensitive property in water, that is, swelling at a higher temperature and shrinking at a lower temperature.

Synthesis of cationic N‐[3‐(dimethylamino)propyl]methacrylamide brushes on silicon wafer via surface‐initiated RAFT polymerization

“…Grafting parameters, including grafting density, σ (chain per nm 2 ), and average distance between grafting sites, D (nm), were calculated from the ellipsometric thickness, h (nm), using eqs 1–340 where ρ (1.27 g/cm 3 ) is the density of dry poly(DMAPMA) film,41 N A is Avogadro's number, and M n the number‐average molecular weight of the grafted polymer chains, which is assumed to be similar to that of the free polymer in solution. The expected poly(DMAPMA) chain conformation in ambient conditions was deduced from the comparison of D with the corresponding Flory radius ( R F,coll. )…”

The Influence of Synthesis Method on Characteristics of Buffer and Organic Solutions of Thermo- and pH-Responsive Poly(N-[3-(diethylamino)propyl]methacrylamide)s

“…N- [3-(dimethylamino)propyl]methacrylamide (DMAPMA) is most famous and is a commercially available representative of this class of compounds. In the field of stimuli-responsive materials, DMAPMA is primarily used as a comonomer to impart pH-sensitivity to hydrogels based on acrylic monomers [3][4][5][6][7][8]. The stimuli-sensitivity of DMAPMA homopolymer (PDMAPMA) is manifested in a change in the swelling degree of hydrogels with temperature variation [9], as well as in the phase separation (about 35 • C) of aqueous solutions, but only in a strongly alkaline medium (pH→14) [10].…”

Photopolymerization of alicyclic methacrylate hydrogels for controlled release

“…The effect of hydrophobic comonomer on the swelling behavior of hydrogels was investigated by many researchers. [29][30][31][32] The direct reason for slow swelling behaviors of copolymeric hydrogels was the addition of comonomer HCMA, which led to change in polymer secondary structure. HCMA bearing hydrophobic cyclohexyl group was less soluble in water, which would result in heterogeneity in the network and interaction among hydrophobic chains.…”