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Branch point in a polymer. Polymer architecture in polymer science relates to the way branching leads to a deviation from a strictly linear polymer chain. [1] Branching may occur randomly or reactions may be designed so that specific architectures are targeted. [1] It is an important microstructural feature.
In polymer chemistry "cross-linking" usually refers to the use of cross-links to promote a change in the polymers' physical properties. When "crosslinking" is used in the biological field, it refers to the use of a probe to link proteins together to check for protein–protein interactions , as well as other creative cross-linking methodologies.
Cross-linked polymers: Wide-meshed cross-linked polymers are elastomers and cannot be molten (unlike thermoplastics); heating cross-linked polymers only leads to decomposition. Thermoplastic elastomers , on the other hand, are reversibly "physically crosslinked" and can be molten.
Gelation occurs when a polymer forms large interconnected polymer molecules through cross-linking. [1] In other words, polymer chains are cross-linked with other polymer chains to form an infinitely large molecule, interspersed with smaller complex molecules, shifting the polymer from a liquid to a network solid or gel phase.
Linear topology is a special topological structure that exclusively has two nodes as the termini without any junction nodes. High-density polyethylene (HDPE) could be regarded as a linear polymer chain with very small amount of branching, the linear topology has been listed below: [9] Linear chains capable of forming intra-chain interactions can fold into a wide range of circuit topologies.
Like polymers in general, SMPs cover a wide range of properties from stable to biodegradable, from soft to hard, and from elastic to rigid, depending on the structural units that constitute the SMP. SMPs include thermoplastic and thermoset (covalently cross-linked) polymeric materials.
After removal of the stimulus, the bonds reform and, in the ideal case, the original cross-link density is restored. This temporary decrease in cross-link density enables very fast topology rearrangements in dissociative CANs, such as viscous flow and stress relaxation, which allows the reprocessing of covalently cross-linked polymer networks.
Highly cross-linked UHMWPE materials were clinically introduced in 1998 and have rapidly become the standard of care for total hip replacements, at least in the United States. [1] These new materials are cross-linked with gamma or electron beam radiation (50–105 kGy) and then thermally processed to improve their oxidation resistance. [ 1 ]