Effects of Chemical Modifications on the Thermoresponsive Behavior of a PDMAEA-b-PNIPAM-b-POEGA Triblock Terpolymer

Abstract

In this work, the synthesis, selective chemical modifications, and self-assembly behavior in aqueous media of a novel poly(2-(dimethylamino)ethyl acrylate)20-b-poly(N-isopropylacrylamide)11-b-poly(oligo ethylene glycol methyl ether acrylate)18 (PDMAEA20-b-PNIPAM11-b-POEGA18) dual-responsive (pH and temperature) and triply hydrophilic amino-based triblock terpolymer are reported. The amine functional triblock terpolymer was synthesized by sequential reversible addition fragmentation chain transfer polymerization (RAFT) polymerization and molecularly characterized by size exclusion chromatography (SEC) and 1H-NMR spectroscopy that evidenced the success of the three-step polymerization scheme. The tertiary amine pendant groups of the PDMAEA block were chemically modified in order to produce the Q1PDMAEA20-b-PNIPAM11-b-POEGA18 as well as the Q6PDMAEA20-b-PNIPAM11-b-POEGA18 quaternized triblock terpolymers (Q1 and Q6 prefixes show the number of carbon atoms (C1 and C6) attached on the PDMAEA groups) using methyl iodide (CH3I) and 1-iodohexane (C6H13I) as the quaternizing agents and the SPDMAEA20-b-PNIPAM11-b-POEGA18 sulfobetainized triblock terpolymer using 1,3 propanesultone (C3H6O3S) as the sulfobetainization agent. The self-assembly properties of the triblock terpolymers in aqueous solutions upon varying temperature and solution pH were studied by light scattering and fluorescence spectroscopy experiments. The novel triblock terpolymers self-assemble into nanosized aggregates upon solution temperature rise above the nominal lower critical solution temperature (LCST) of the temperature-responsive PNIPAM block. The remarkable stimuli-responsive self-assembly behavior of the novel triblock terpolymers in aqueous media make them interesting candidates for biomedical applications in the fields of drug and gene delivery.

PEG-Based Methacrylate Tetrablock Terpolymers: How Does the Architecture Control the Gelation?

“…Other amphiphilic and thermoresponsive triblock bipolymers have been investigated as thermoresponsive gels. These include polymers based on poly­(ethylene glycol) (PEG) which consist of a block with an ester-based backbone, − (meth)­acrylate and acrylamide polymers, − such as polymers based on N -isopropylacrylamide (NIPAAm), ,,− PEG (meth)­acrylate units, − and 2-(dimethylamino)­ethyl methacrylate (DMAEMA), and poly­(oxazoline)­s. − Amphiphilic triblock terpolymers have also been investigated, and the position of the block has been proven critical for the final application. ,− Interestingly, when triblock bi- or terpolymers were compared to their diblock counterparts, it was concluded that triblock copolymers form stronger gels at lower temperatures and concentrations. ,− Therefore, increasing the number of blocks and/or comonomers seems to favor gelation. Due to their unique reversible thermogelling properties, thermoresponsive gels have become popular candidates in tissue engineering, ,− drug delivery, ,− and three-dimensional (3-D) printing ,− fields.…”

Latest Advances on the Synthesis of Linear ABC-Type Triblock Terpolymers and Star-Shaped Polymers by RAFT Polymerization

“…Giaouzi et al [ 57 ] worked on the synthesis and self-assembly in H 2 O of poly(2-(dimethylamino)ethyl acrylate)- b -poly( N -isopropylacrylamide)- b -poly(oligo ethylene glycol methyl ether acrylate), (PDMAEA- b -PNIPAM- b -POEGA) triple hydrophilic and double-responsive (temperature and pH) triblock terpolymers. The synthesis was achieved by three-step RAFT polymerization in dioxane, involving 2-(dodecylthiocarbonothioylthio)-2-methylpropionionic acid as the CTA.…”

Polymerizations by RAFT: Developments of the Technique and Its Application in the Synthesis of Tailored (Co)polymers

“…Some of the latest reports are based on linear di‐ and triblocks where one block is the well‐studied poly( N ‐isopropylacrylamide) to confer the thermoresponsivity and other blocks often contain a weak acid or base such as (meth)acrylic acid and 2,2 dimethyl ethyl (meth)acrylate (DMAEMA). Some examples are: PDMAEMA‐ b ‐PNIPAm‐ b ‐POEGA, [ 167 ] PDMAEMA‐ b ‐PNIPAm where the 2 blocks are connected via a host–guest interaction based on pillar[5]arene and viologen ( Figure ), [ 168 ] PAA‐ b ‐PNIPAm, [ 169 ] PMAA‐ b ‐PNIPAm, [ 170 ] and PNIPAm‐ b ‐PDOPA where the PNIPAm chain ends are modified with a 3,4‐dihydroxy‐ l ‐phenylalanine moieties forming spherical nanoparticles with temperature/pH dual‐stimuli‐responsive character. [ 171 ] Other examples including PNIPAM‐ b ‐P(DPA‐ co ‐TPE) and P(NIPAM‐ co ‐TPE)‐ b ‐PDPA where tetraphenylethylene (TPE) is used as a single‐color “turn on” fluorescence probe used to differentiate temperature or pH stimulus in solutions or in the cells.…”