Amphiphilic Model Networks Based on PEG and PCL Tetra-arm Star Polymers with Complementary ...
发表时间：2022-10-27 11:35作者：Frank Böhme来源：《Macromolecules》
Amphiphilic Model Networks Based on PEG and PCL Tetra-arm Star Polymers with Complementary Reactivity
Carolin Bunk, Lucas Löser, Nora Fribiczer, Hartmut Komber, Lothar Jakisch, Reinhard Scholz, Brigitte Voit, Sebastian Seiffert, Kay Saalwächter*, Michael Lang*, and Frank Böhme*
Leibniz-Institut für Polymerforschung Dresden e. V., Hohe Str. 6, 01069 Dresden, Germany
Macromolecules 2022, 55, 15, 6573–6589
Publication Date: August 1, 2022
A new approach for the synthesis of model amphiphilic polymer co-networks (ACNs) based on a hetero-complementary coupling reaction of a 2-(4-nitrophenyl)-benzoxazinone terminated tetra-arm polycaprolactone star (tetra-PCL) with an amino-terminated tetra-arm polyethylene glycol star (tetra-PEG) is presented. The reaction conditions (solvent, concentration, and temperature) were varied widely. Reaction kinetics and gelation were analyzed with high-resolution NMR spectroscopy and computer simulations. The results agree with a nearly homogeneous mixture where local composition fluctuations affect kinetics only after most of the molecules are attached to the gel. Viscometry, dynamic light scattering data, and literature data for the solubility parameters were combined to provide estimates for the Flory–Huggins interaction parameter of the two star polymers in toluene, chloroform, and THF as solvents. These estimates allow one to collapse equilibrium swelling data in different solvents on a universal curve. Multiple quantum NMR analysis shows an enhanced formation of double connections between the same pair of stars as compared to preceding work on tetra-PEG gels made by the same cross-linking strategy but with a different coupling reaction. Besides this last observation, the remaining results indicate that the networks possess a near model-like structure with only a small fraction of pending arms as the most relevant type of network defects.