Precisely Tunable Sol–Gel Transition Temperature by Blending Thermoresponsive ABC Triblock Terpolymers

Abstract

Here, we report a facile methodology to control the sol−gel transition temperature (T gel ) of a physically crosslinked hydrogel by blending two kinds of ABC triblock terpolymers. Well-defined triblock terpolymers including thermosensitive N-isopropylacrylamide (NIPAAm), ABC1, and ABC2, were prepared by sequential reversible addition− fragmentation chain transfer polymerization. The chemical structure as well as the molecular weight of the A and B blocks for both polymers are identical, whereas the C blocks are different. The C block of ABC1 (C1) is a statistical copolymer of NIPAAm with hydrophobic n-butyl acrylate (BA), while that of ABC2 (C2) is a PNIPAAm homopolymer. Independently prepared ABC triblock terpolymer solutions exhibit well-defined sol− gel transitions. The T gel of ABC1 is lower than that of ABC2 since hydrophobic BA is copolymerized into block C1. Remarkably, the T gel varies linearly within this temperature range by simply blending the two polymers, while the resultant gel strength (∼G′) remains almost unchanged. Therefore, the T gel can be precisely adjusted by the mixing ratio of the two polymers. This method for straightforward manipulation of T gel has great potential for various soft material applications such as biomaterials for tissue engineering, drug delivery systems, and injectable gels.

Alginate-g-PNIPAM-Based Thermo/Shear-Responsive Injectable Hydrogels: Tailoring the Rheological Properties by Adjusting the LCST of the Grafting Chains

“…In the inset of Figure 6 b, the data were plotted to apply the Arrhenius Equation (1): τ = τ o exp[−E a /RT] where E a is the apparent activation energy, which represents the energy barrier the network stickers need to overcome to escape from their crosslinking nanodomains (micellar cores), allowing relaxation [ 24 , 32 ]. E a was estimated 870 kJ/mol, which is comparable with the 619 kJ/mol reported for a triblock copolymer constituted of poly( N,N -dimethylacrylamide), end-capped with PNIPAM-based random copolymers of poly(NIPAM 82 - co -butyl acrylate 18 ) and poly(NIPAM 95 - co -butyl acrylate 5 ) [ 37 ]. In this copolymer, the PNIPAM sticky end-blocks have been enriched with the hydrophobic butyl acrylate moieties in 82/18 (mol %) content.…”

Hydrogels in Electrophoresis: Applications and Advances

“…Transitioning electrophoresis from SGE and CE to microfluidic devices is one of the paths in the future. During the past two to three decades, hydrogels have evolved from relatively inert and static materials to those incorporating sophisticated feedback mechanisms, 94,95 from the macroscale to micro/nano scale, 96,97 and the next step is to achieve more controlled physicochemical properties, 98,99 and enhanced functionality. [100][101][102] It can be foreseen that more advanced hydrogels will be utilized in electrophoretic separations in the future.…”

Controlling properties of thermogels by tuning critical solution behaviour of ternary copolymers

“…6 When ABA or ABC triblock copolymers containing terminal PNIPAM blocks are raised above their LCST, the terminal blocks phase separate and form micelles that are connected into a 3D network by a hydrophilic block. [7][8][9][10][11][12][13][14] As the LCST of these PNIPAM blocks are the fundamental feature enabling thermogel formulation, modulation of this critical solution behaviour provides a unique opportunity to tune thermogel properties. It is well known that the LCST of PNIPAM can be modulated through copolymerization, whereby inclusion of hydrophobic monomers, such as tertbutyl acrylamide (TBAM), decreases the LCST and inclusion of hydrophilic monomers, such as hydroxyethyl acrylamide (HEAM), increases the LCST.…”