Photopolymerised thermo-responsive poly(N,N-diethylacrylamide)-based copolymer hydrogels for potential drug delivery applications

Abstract

Novel thermo-sensitive N,N-diethylacrylamide (DEAAm) based copolymer hydrogels were prepared via UV-induced free radical bulk polymerisation. UV polymerisation was employed to avoid the use of potentially toxic solvents; solution polymerisation has been the most common means for the preparation of PDEAAm-based hydrogels in the literature to date. The resultant hydrogels were analysed using nuclear magnetic resonance, Fourier transform infrared spectroscopy and modulated differential scanning calorimetry. Parameters such as the crosslinking degree and the nature of the incorporated hydrophilic component, N-vinyl-2-pyrrolidone (NVP) or N,N-dimethylacrylamide (DMAAm) were found to impact hydrogel structure, mechanical properties and swelling kinetics. Pulsatile swelling studies indicated that the hydrogels had thermo-reversible properties which were greatly affected by test temperature, nature of hydrophilic monomer used and crosslinker content. Aminophylline was selected as a model solute for drug loading and release studies by thermal deswelling in HCl buffer (pH 1.4) and phosphate buffer media (pH 6.8). The observed lag time prior to significant drug release from the more crosslinked P(DEAAm-NVP) hydrogels could make them suitable for delayed specific release in the intestine and potential alternatives to layers or membranes in timespecific and site-specific swelling-controlled drug delivery systems.

Thermoresponsive and biocompatible poly(vinyl alcohol)‐graft‐poly(N,N‐diethylacrylamide) copolymer: Microwave‐assisted synthesis, characterization, and swelling behavior

“…As can be seen from the spectrum, the signals at d 5 0.89 and d 5 2.43 ppm correspond to methyl (ACH 3 ) protons and methine (ACHAC@O) protons of the PDEAAm chain, respectively. 22,23 Moreover, a singlet signal at d 5 3.56 ppm was ascribed to the pendant methylene protons (ACH 2 CH 3 ) of PDEAAm, verifying grafting of PDEAAm chains onto PVA.…”

“…At 25 8C, below the LCST, hydrophilic hydrogen-bonding interactions between the water and PVA-g-PDEAAm membrane become more dominant, causing enhanced water sorption and swelling ratio. 23 On the other hand, at 37 8C, above the LCST, the hydrogen-bonding interactions are disrupted, and the hydrophobic group interactions between the ethyl groups in the PVA-g-PDEAAm membrane become dominant, causing reduced water sorption and swelling ratio. 6 Therefore, the PVA membrane gains a temperature-dependent swelling behavior via grafting of PDEAAm chains, which can be beneficial for potential wound dressing applications or transdermal drug delivery.…”

Fabrication and characterization of bifunctional spherical polyelectrolyte brushes

“…[28][29][30][31] AA monomer is a common material for polyelectrolyte chains and has been proved to be an effective way to adjust the LCST of thermo-sensitive polymers. [32][33][34] Two sets of SPBs (P(NIPAM-AA) and P(AA-DEA)) were made by photoemulsion polymerization. Due to the different activity of comonomers (NIPAM > AA and AA > DEA), the AA units were distributed around the peripheries of P(NIPAM-AA) and inner shell of P(AA-DEA).…”

Synthesis and behaviour of PEG-b-PDEAm block copolymers in aqueous solution

“…Copolymerization with a hydrophilic monomer can control phase transition behaviour. When Nvinylpyrrolidone is used as comonomer the LCST improves until 36°C when the copolymers are synthesised by a RAFT process using a trithiocodecanoic acid-2-cyanoisopropyl as RAFT agent and until 37,6 °C when synthesized by UV initiated polymerization process 21,22 (D ref Ngadaonye et E polymer 9 ) It is known that polymer topology affects LCST values. It is known that polymer topology affects LCST values.…”