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Other polymers formed by cationic polymerization are homopolymers and copolymers of polyterpenes, such as pinenes (plant-derived products), that are used as tackifiers. In the field of heterocycles, 1,3,5-trioxane is copolymerized with small amounts of ethylene oxide to form the highly crystalline polyoxymethylene plastic.
Living cationic polymerization is a living polymerization technique involving cationic propagating species. [1] [2] It enables the synthesis of very well defined polymers (low molar mass distribution) and of polymers with unusual architecture such as star polymers and block copolymers and living cationic polymerization is therefore as such of commercial and academic interest.
Another type of lipid-nanoparticle that can be used for drug delivery to the brain is a cationic liposome. These are lipid molecules that are positively charged. [6] One example of cationic liposomes uses bolaamphiphiles, which contain hydrophilic groups surrounding a hydrophobic chain to strengthen the boundary of the nano-vesicle containing ...
Unsymmetrically substituted oxetanes polymerizes according to ability of attacking one or both alpha-carbons of the propagation centre. Unsubstituted and 3-substituted derivatives polymerize in symmetrical manner, but 2-substituted derivatives can form any of the basic types of polymer chain connections (head-to-tail, head-to-head and tail-to-tail).
In polymer chemistry, ionic polymerization is a chain-growth polymerization in which active centers are ions or ion pairs. [2] It can be considered as an alternative to radical polymerization, and may refer to anionic polymerization or cationic polymerization. [3] As with radical polymerization, reactions are initiated by a reactive compound.
Since polymer chains are often in close proximity to other parts of the same chain or to other chains, like-charged parts of the polymer repel each other. This repulsion leads to a swelling of the polymer. [citation needed] Polymers can also form micelles (spheres) in response to a change in pH. This behavior can occur with linear block copolymers.
ampholytic polymer: Polyelectrolyte composed of macromolecules containing both cationic and anionic groups, or corresponding ionizable groups. (See Gold Book entry for note.) [ 4 ] Polyelectrolytes that bear both cationic and anionic repeat groups are called polyampholytes .
Flocculation (except in polymer science) Process of contact and adhesion whereby dispersed molecules or particles are held together by weak physical interactions ultimately leading to phase separation by the formation of precipitates of larger than colloidal size.