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

Here, we report a facile methodology to control the sol–gel transition temperature (<i>T</i>_gel) of a physically cross-linked hydrogel by blending two kinds of ABC triblock terpolymers. Well-defined triblock terpolymers including thermosensitive <i>N</i>-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 <i>n</i>-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 <i>T</i>_gel of ABC1 is lower than that of ABC2 since hydrophobic BA is copolymerized into block C1. Remarkably, the <i>T</i>_gel varies linearly within this temperature range by simply blending the two polymers, while the resultant gel strength (∼<i>G</i>′) remains almost unchanged. Therefore, the <i>T</i>_gel can be precisely adjusted by the mixing ratio of the two polymers. This method for straightforward manipulation of <i>T</i>_gel has great potential for various soft material applications such as biomaterials for tissue engineering, drug delivery systems, and injectable gels