Polymerization, radical macromers

Choi et al. [53] have successfully used both water-soluble and oil-soluble initiators in the miniemulsion polymerization of styrene. Alducin and Asua [119] have studied the MWD of polystyrene miniemulsion polymerized with oil-soluble initiators. Rodriguez et al. [61] have developed a mathematical model of seeded miniemulsion polymerization with oil-soluble initiator. Blythe et al. [ 120] have successfully carried out miniemulsion polymerization of styrene with AMBN (oil-soluble). Ghazaly et al. [117] have used AIBN for the miniemulsion copolymerization of a hydrophobic bifunctional macromer. The polymerization progressed much faster when KPS was used than when AIBN was used. This may be due to the tendency of oil-soluble initiator radicals to recombine before initiating polymerization, as discussed by Luo. 

The copolymerization is performed in solution with radical-forming initiators at temperatures of about 70 °C. The silicone macromer contains polymerizable vinyl groups on both chain ends. Such silicone macromers are produced by Wacker GmbH and are available with different chain lengths. The copolymerization with vinyl acetate is very facile and take place statistically [2] after polymerization, no double bonds can be found. To avoid crosslinking, the molecular weight has to be adjusted by the use of chain transfer agents or by the solvent and its concentration. 

Donini et al. reported the preparation of poly(methacrylic add-g-polyethylene glycol) nanospheres by solntion or precipitation polymerization. The free radical polymerization of methacryUc acid with PEG macromer was carried out using a photoinitiator in water. Pluronics-based polymers were used to prevent the aggregation of these nanospheres and to render than redispersion ability. 

Volume shrinkage can be attributed to the formation of covalent bonds during photopolymerization bringing monomers, macromers, or prepolymers in a densely packed formation when compared with the initial liquid (viscous) state. Volume shrinkage is one of the major concerns in radical photopolymerization, especially for in situ polymerized systems, where the photocurable formulation in the form of viscous liquid, or paste, injected into a predefined volume... 

In this review, the term macromer is used to describe oligomer or polymer precursors that undergo reversible association to form supramolecular polymers or networks. Macromer synthesis, although a crucial aspect of supramolecular science, is also out of the scope of this review. Several comprehensive reviews of the synthesis of H-bonding polymers are available [10, 11,42] and primarily describe the application of controlled radical polymerization techniques, including atom-transfer radical polymerization (ATRP), reversible addition-fragmentation chain transfer (RAFT) polymerization, and nitroxide-mediated polymerization (NMP). For synthesis of telechelic polymers, avoiding monofunctional impurities that can act as chain stoppers is crucially important [43],... 

Macromers can be prepared not only by anionic polymerization, but also by cationic and radical polymerization. Kennedy and his coworkers utilized the inifer method of cationic polymerization in synthesizing polyisobutylene macromers, as follows ... 

Macromers obtained by radical polymerization have wide molecular weight distributions, due to chain transfer, whereas the synthesis of macromers using cationic polymerization must be carried out at low temperature in order to avoid chain transfer. Only the method of anionic polymerization has the... 

Anionic and Cationic Polymerizations o Radical Polymerization Advances o Coordination Polymerizations 0 Step-Growth Polymerization Advances 0 Synthesis of Tactic Polymers o Stereoblock Copolymers o Dispersion Polymerizations o Cellulosic Graft Copolymers o Diels-Alder Polymer Forming Reactions o A New Path To Phenolic Resins o Nitrogen Heterocycle Polymerizations o Optically Active Polymers o Poly (Phenylene Sulfide) o Poly (Aryl Ethers) o (Poly (Aryl Ether Sulfones) o Epoxy and Isocyanate Resin Replacement o Azlactone Functionalized Oligomers o Epoxy Resin-Isocyanate Reactions o Chelating Polymers o Oxazoline Functionalized Polymers o Poly (Alkyl Methacrylates) o Macromers... 

Photolabile acrylate monomer and bifunctional cross-linker photodegradable hydrogels synthesized by free-radical polymerization of the PEG macromers, which are used as photolabile 3D substrates for dynamic cell culture. (Source Adapted with permission from Reference [109a].)... 

Santerre, J. P., K. Woodhouse, G. Laroche, and R. S. Labow 2005. Understanding the biodegradation of polyurethanes From classical implants to tissue engineering materials. Biomaterials. 26 7457-70. Sawhney, A. S., C. P. Pathak, and J. A. Hubbell 1993. Bioerodible hydrogels based on photopolymerized poly(ethyleneglycol)-co-poly(alpha-hydroxyacid) diacrylate macromers.Macromo/ec /es. 26 581-87. Sciannamea, V., R. Jerome, and C. Detrembleur 2008. In-situ nitroxide-mediated radical polymerization (NMP) processes Their understanding and optimization. Chemical Reviews. 108 1104-26. 

The introduction of monofunctional POSS macromers into an organic polymer by polymerization at the single reactive site leads to POSS-modified polymers. POSS macromers were incorporated in linear polymers, such as methacrylates, styrenics, norbomenes, ethylenes, propylenes, and urethanes in order to improve mechanical or thermal properties. If a multifunctional POSS with cross-linkable functions is used cross-linked materials are indeed formed. Star polymers are achieved if a multifunctional POSS unit contains initiator groups and a controlled polymerizatiOTi occurs, such as atom transfer radical polymerization. 

SynQiesis of graft copolymers wifli TBMA. The free radical polymerizations were carried out as described for the reaction with TBCS, however, using a feed of lSwt% or 7wt% of the macromers (with respect to TMBA). A reaction period of 4 days was used. Dialysis techniques were applied to remove any unreacted mat ial. Standard procedures were used for purification. 

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