Hydrophobic/Hydrophilic Triblock Copolymers: Synthesis and Properties of Physically Cross-Linked Hydrogels

Abstract

Hydrophobic/hydrophilic triblock copolymers of poly-(2-(N-ethylperfluorooctanesulfonamido)ethylmethyl acrylate) and poly(N,N′-dimethylacrylamide) (PD) were synthesized by sequential reversible addition−fragmentation chain transfer polymerization. Physically cross-linked hydrogels were produced by immersing compression-molded triblock copolymers into water. The copolymers and their hydrogels were characterized by differential scanning calorimetry, thermogravimetric analysis, thermal desorption-GC/MS analysis, swelling isotherms, wide-and small-angle X-ray scattering, and dynamic mechanical analysis. The equilibrium water sorption of the hydrogels depended on the length of the water-soluble polymer block (PD), and the block copolymers swelled more in water than a random copolymer of the same composition. The block copolymer hydrogels were viscoelastic, though the frequency dependence of the dynamic modulus was weak. The dynamic modulus of the block copolymer hydrogels ranged from ∼10 3 to 4 × 10 4 Pa, which was much lower than the modulus of a random copolymer hydrogel of the same composition.

Effect of Chemical Crosslinking on Properties of Polymer Microbeads: A Review

“…Polymer cross-linking may be reversible or irreversible depending upon the nature of the cross-linking. Three main types of cross-linking methods are widely studied [24][25][26]. These cross-linking methods are chemical, physical, and biological [27].…”

Properties of conductive polymer hydrogels and their application in sensors

“…Noncovalent interactions enable autonomous self‐healing, including hydrogen bonding, hydrophobic bonding, host–guest interaction, and electrostatic ionic force . Chen et al .…”

“…Noncovalent interactions enable autonomous self-healing, including hydrogen bonding, hydrophobic bonding, host-guest interaction, and electrostatic ionic force. 51,59,60 Chen et al introduced multiple hydrogen-bonding 2-ureido-4[1H]pyrimidinone (UPy) groups as crosslinking points into PAni/ PSS network to form self-healing hydrogel. 61 Dynamic reversibility of hydrogen bonds is beneficial to energy dissipation and network reconstruction, which is the fundamental mechanism of self-healing properties of hydrogels fracture surface at room temperature and show 3600% of the original extensibility.…”

Thermo-reversible sol–gel transition of aqueous solutions of patchy polymers

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