Ring-opening polymerization hydrolytic polymerization

Nylon-6 is the polyamide formed by the ring-opening polymerization of S-caprolactam. The polymerization of S-caprolactam can be initiated by acids, bases, or water. Hydrolytic polymerization initiated by water is often used in industry. The polymerization is carried out commercially in both batch and continuous processes by heating the monomer in the presence of 5—10% water to temperatures of 250—280°C for periods of 12 to more than 24 h. The chemistry of the polymerization is shown by the following reaction sequence. 

Polylactides, 18 Poly lactones, 18, 43 Poly(L-lactic acid) (PLLA), 22, 41, 42 preparation of, 99-100 Polymer age, 1 Polymer architecture, 6-9 Polymer chains, nonmesogenic units in, 52 Polymer Chemistry (Stevens), 5 Polymeric chiral catalysts, 473-474 Polymeric materials, history of, 1-2 Polymeric MDI (PMDI), 201, 210, 238 Polymerizations. See also Copolymerization Depolymerization Polyesterification Polymers Prepolymerization Repolymerization Ring-opening polymerization Solid-state polymerization Solution polymerization Solvent-free polymerization Step-grown polymerization processes Vapor-phase deposition polymerization acid chloride, 155-157 ADMET, 4, 10, 431-461 anionic, 149, 174, 177-178 batch, 167 bulk, 166, 331 chain-growth, 4 continuous, 167, 548 coupling, 467 Friedel-Crafts, 332-334 Hoechst, 548 hydrolytic, 150-153 influence of water content on, 151-152, 154... 

As early as 1895, the synthesis of polydichlorophosphazene was attempted by H.N. Stokes by thermal ring-opening polymerization of hexachloro-triphosphazene [(NPCl2)3]. The product obtained by H.N. Stokes was a high-molecular weight cross-linked rubbery material called inorganic rubber which is insoluble in all solvents and hydrolytically decomposes into phosphates, ammonia, and hydrochloric acid in the presence of moisture. Because of its insolubility and hydrolytic instability, the polymer found no technological application and remained as a laboratory curiosity. 

The hybrid polymer 140 is generated by a thermal ring-opening polymerization (ROP) process (Scheme 10).300,301 Polymers containing three-coordinate sul-fur(IV) are generally hydrolytically sensitive even when the chloro substituents are replaced by phenoxy groups.302... 

Over the years we have developed methods for the direct synthesis of hydrolytically and/or enzymatically degradable microspheres by ring-opening polymerization of e-caprolactone and lactides [6-12]. The diameters of these microspheres are usually less than 3 xm. In this chapter we discuss... 

Anionic ring opening polymerization of lactams to generate polyamides has been studied quite extensively by Sebenda [8-10], Sekiguchi [11], and Wichterle [12-13], among others, in academia, and by Gabbert and Hedrick [14] and by us [23-25] in industry. By far, caprolactam is the most studied lactam and the nylon 6 prepared by this route compares favorably in properties with that prepared by conventional hydrolytic polymerization. 

Research Focus Development of ring-opening polymerization monomers that are susceptible to hydrolytic and photolytic degradation. 

The example in Scheme 1.29 of the ring-opening polymerization of s-caprolactam is given since it has also been exploited in reactive processing (Brown, 1992). In the example given the initiator is 0.2%-0.3% sodium lactamate. The anionic polymerization (such as that in Scheme 1.29) is faster than cationic or hydrolytic polymerization. 

One of the oldest and yet isost important ring opening polymerizations as eluded to earlier is the hydrolytic polymerization of e caprolactam (HEXANOLACTAM). The overall processes are outlined in Scheme VII. For detailed discussions... 

Polyamides are produced commercially by two routes. First is the polycondensation of aminoacids or diamines with diacids, and the second route is the ring-opening polymerization of lactams l. The ring-opening process can be accomplished with anionic or cationic initiators and also in the presence of water by a hydrolytic process. Nylon-6 (poly-e-caprolactam) and Nylon-12 (poly-co-dodecanelactam) are commercially produced mostly by the hydrolytic process, in which the reaction control is easier and the properties of the product better than in polycondensation. 

While the lower-molecular-weight polysiloxanes can be synthesized by the hydrolytic step polymerization process, the higher-molecular-weight polymers are synthesized by ring-opening polymerization using ionic initiators ... 

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