Crosslinked seed network

Other types of IPN s exist, of course. For example, Johnson and Labana (1972) recently synthesized a modified type of latex IPN as follows A crosslinked polymer network I prepared by emulsion polymerization served as a seed latex to linear polymer II. The resulting semi-IPN exhibited the usual core-shell morphology. After suitable coagulation and molding steps, polymer II was selectively crosslinked to form a macroscopic network, resulting in a thermoset material. The topology of this IPN therefore involves microscopic network islands of polymer I embedded in a continuous network of polymer II. 

Another scenario about the impact of crosslinked seed particles is briefly described as follows. When a crosslinked seed latex is swollen by second-stage monomers, the crosslinked network structure expands due to the solvency power of the newly incorporated monomers. When those monomers are con-... 

Sheu and coworkers [111] produced polysty-rene-polydivinylbenzene latex interpenetrating polymer networks by the seeded emulsion polymerization of styrene-divinylbenzene in the crosslinked uniform polystyrene particles. In this study, a series of uniform polystyrene latexes with different sizes between 0.6 and 8.1... 

Recently, core-shell type microgels, which contain a hydrophobic core and a hydrophilic thermosensitive shell, have become attractive for scientists because such systems can combine the properties characteristic of both the core and the shell [53], We have prepared core-shell microgel particles consisting of a poly(styrene) core onto which a shell of polyCA-isopropylacrylamide) (PS-PNIPA) has been affixed in a seeded emulsion polymerization [54-56], In this case, the ends of the crosslinked PNIPA chains are fixed to a solid core, which defines a solid boundary of the network. In this respect, these core-shell latex particles present crosslinked polymer brushes on defined spherical surfaces. The solvent quality can be changed from good solvent conditions at room temperature to poor solvent conditions at a temperature... 

As the seed crystal meets the gel layer on the rotor surface, the adsorbed polymer molecules make loops extending into the solution and other molecules become entangled with those loops and with each other. Hms, a network with physical crosslinks adheres to the rotor sxuface. As shearing motion is encoimtered, the network of adsorbed molecules is extended and small embryonic crystallites will... 

Latex IPN refers to a material where both networks appear on a single latex particle. Synthesized by sequential polymerization, a core-shell structure is built up. A crosslinked polymer I in latex form is used as the seed latex, and upon the addition of monomer II, crosslinker, and activator (but no new soap, to discourage the formation of new particles), followed by polymerization of monomer II, the IPN is formed. Then each latex particle, ideally, consists of two crosslinked polymer molecules. 

Ryan and Crochowski teach the use of acrylic latex IPNs dispersed in PVC copolymers to produce transparent, impact-resistant vinyls (see Table 8.1). A three-stage polymerization of the latex particles is required. A crosslinked rubbery latex such as poly(butyl acrylate) makes up the seed latex. A crosslinked vinyl aromatic, such as polystyrene, makes up network II. A linear poly(alkyl methacrylate), such as PMMA, forms polymer III. The finished latex is coagulated and blended with PVC to produce a tough, transparent plastic. Transparency is achieved by a close match of refractive indices. 

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