Ring-opening polymerization ROP route

Poly(lactic acid) (PLA) is produced from the monomer of lactic acid (LA). PLA can be produced by two well-known processes — the direct polycondensation (DP) route and the ring-opening polymerization (ROP) route. Although DP is simpler than ROP for the production of PLA, ROP can produce a low-molecular-weight brittle form of PLA. Generally, several substances are involved in the production of PLA, and these relationships have been summarized in Figure 2.1. The lactic acid for the process is obtained from the fermentation of sugar. Lactic acid is converted to lactide and eventually to PLA. It should be noted that there are two different terms, poly(lactic acid) and polylactide , for the polymer of lactic acid. Both terms are used... 

The second route of producing PLA is to ring-open polymerize (ROP) lactide into high molecular weight (Mw > 100,000) PLA. ROP are most commonly studied due to the possibility of an accurate control of the chemistry, and the properties of the resulting polymers in a more controllable manner. 

Several process routes have been developed or are practised on industrial scale Ring Opening Polymerization (ROP), Direct Polycondensation in high boiling solvents (DP-S) and Direct Polymerization in bulk followed by chain extension with reactive additives. 

Synthetic Routes to Metal-Containing Polymers 33 1.5.2.2.3 Ring-Opening Polymerization (ROP)... 

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... 

Ring-opening polymerization (ROP) is the most efficient route to prepare PPEs with a controlled structure (Scheme 6.7). The first attempts to... 

In contrast, the chemical process could lead to various ratio of l- and o-lactic acid. Indeed, the chemical reactions leading to the formation of the cychc dimer, the lactide, as an intermediate step to the production of PLA, could lead to macromolecular chains with L- and o-lactic acid monomers. This mechanism of ring-opening polymerization (ROP) from the lactide explains the formation of two enantiomers. This ROP route has... 

Poly(dichlorophosphazene), [NPCUjm can be prepared by several routes. The traditional route is the ring-opening polymerization (ROP) of N3P3CI6. Although, as discussed above, Stokes as early as in late 1800 s had observed the formation of crosslinked poly(dichlorophosphazene), it is to the credit of Allcock that he found the correct recipe for isolation of un-crosslinked linear poly(dichlorophosphazene) [21]. He and his co-workers have made the following important and crucial experimental observations. 

PLA can be produced by condensation polymerization directly from its basic building block lactic acid, which is derived by fermentation of sugars from carbohydrate sources such as com, sugarcane, or tapioca, as will be discussed later in this chapter. Most commercial routes, however, utilize the more efficient conversion of lactide—the cyclic dimer of lactic acid— to PLA via ring-opening polymerization (ROP) catalyzed by a Sn(ll)-based catalyst rather than polycondensation [2-6]. Both polymerization concepts rely on highly concentrated polymer-grade lactic acid of excellent quality... 

While direct polycondensation of LA should be the cheapest route to PLA, the ring-opening polymerization (ROP) of lactide is the method used commercially. Though the ROP of lactide was first studied long back (1932), only low molecular weight polymer was produced until lactide purification techniques were devised by DuPont in 1954. Over the past decades, many researchers have studied the... 

Zechel, D.L., Hultzsch, K.C., Rulkens, R. et al. (1996) Thermal and transition-metal-catalyzed ring-opening polymerization (ROP) of [l]silaferrocenophanes with chlorine substituents at silicon A route to tunable poly (ferrocenylsilanes). Organometallics, 15,1972. 

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