Synthetic techniques ring-opening polymerization

In contrast to the limitations of the step-growth polymerization techniques, ring-opening polymerization (ROP) of cyclic esters may provide high-molecular-weight aliphatic polyesters (up to lOOkgmol" ) under mild conditions. " ROP is the prefened synthetic pathway used in industry, and... 

Synthetic PAs are produced by polycondensation of bifunctional monomers or by cationic and anionic ring-opening polymerization of lactams. Polymers obtained with the first technique are linear, whereas chain branching may occur with anionic polymerization. Based on their chemical structure, synthetic polyamides may be classified into two categories [1] ... 

PPEs can be prepared using a variety of synthetic routes polycondensation (including transesterification and polyaddition), ring-opening polymerization (ROP), and post-polymerization modification (Scheme 6.2). Each of these techniques has advantages and limitations, which make them suitable... 

Various synthetic techniques have been used to obtain homopolymers and copolymers with defined chemical compositions and low polydispersity (1) living anionic or cationic polymerization [26,27], (2) controlled ring-opening polymerization (CROP) [28], and (3) controlled radical polymerization (CRP), which includes (a) atom transfer radical polymerization, (b) reversible addition-fragmentation chain transfer polymerization (RAFT), and (c) nitroxide mediated radical polymerization (NMP) [29-31]. 

Scheme 7.36 Synthetic scheme for the polymerization of norbornene and its derivatives via free radical polymerization (FRP), ring-opening metathesis polymerization (ROMP), and vinyl addition polymerization (VAP) techniques. Polymers I, II, and III are isomers that differ in their enchainment and physical properties. Co- and terpolymerization of norbornene and derivatives of norbornene with other alicyclic monomers such as maleic anhydride, methyltetracyclododecene carboxylic acid, etc. are also successfully synthesized with this scheme. (Note that 2, 3- and 2,7-enchainments of repeating units are reported in type I polymers. °°)...

Each strategy involves various polymerization techniques, such as conventional and controlled radical polymerizations (CRPs), anionic polymerization, ring-opening metathesis polymerization (ROMP), and cationic polymerization. A judicious combination of a synthetic strategy and a polymerization technique can facilitate the preferential control of certain structural parameters, and this demonstrates distinct advantages with respect to the molecular design, as well as... 

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