polymernetzwerk

A polymernetzwerk, or polymer network, is a three-dimensional, crosslinked assembly of polymer chains in which individual chains are connected by covalent bonds or strong physical associations. The crosslinks prevent dissolution in most solvents and give rise to a gel-like or solid material with a defined elastic response. The density of crosslinks—the crosslink density—and the topology of the network determine swelling, stiffness, and thermal behavior.

Networks can be broadly categorized as permanent covalent networks (thermosets) or reversible/dynamic networks (physically crosslinked or covalent adaptable networks such as vitrimers). They include elastomeric rubbers, hydrogels, and other gel-like materials. Synthesis methods include step-growth polymerization using multifunctional monomers, or chain-growth processes with crosslinking comonomers; post-polymerization crosslinking; and physical crosslinking through hydrogen bonds or ionic interactions. Dynamic networks employ reversible bonds that allow rearrangement under stimuli.

Physical properties depend on crosslink density and polymer flexibility. In swollen networks, the network equilibrium swelling is described by theories such as Flory–Rehner. Characterization often involves determining gel fraction, swelling ratio, rheology, and mechanical testing.

Applications span bioengineering (tissue scaffolds, drug delivery hydrogels), contact lenses, seals and gaskets, soft robotics, membranes, and shape-memory materials. The concept originated in the study of swollen polymers and continues to evolve with advances in dynamic covalent chemistry and nanocomposite networks.