Ring-opening polymerizations behavior

Kudoh R, Sudo A, Endo T (2009) Synthesis of eight-membered lactone having tertiary amine moiety by ring-expansion reaction of 1,3-benzoxazine and its anionic ring-opening polymerization behavior. Macromolecules 42 2327-2329... 

The monomers 3 and 6-8 have the following features in common in their ring-opening polymerization behavior (1) They give polymers rich in the cis units at or above — 60 °C. (2) The ds unit content in these polymers increases with decreasing initial monomer concentration, as depicted in Fig. 1. (3) Polymerization of these monomers at higher initial monomer concentrations and at lower... 

Takata et al. [99] found for two spiro orthocarbonates (119 and 121) having l,4,6,9-tetraoxaspiro[6.6]tridecane skeletons different cationic ring-opening polymerization behavior Irrespective of solvent, initiator, and temperature (from room temperature to 150°C), 119 gave polycarbonate (120), whereas 121 gave poly (ether-carbonate) (122). 

Matsuo, J., Sanda, F., Endo, T., 1998c. Cationic ring-opening polymerization behavior of an aliphatic seven-membered cyclic carbonate, l,3-dioxepan-2-one. Macromolecular Chemistry and Physics 199, 97—102. 

Peckman TJ, Nguyen P, Bourke SC et al. (2001) Ring-opening polymerization behavior of ansa- and spirocycUc a/wa-Zirconocene complexes. OrganometaUics 20 3035-3043... 

Co/Zn double metal cyanide catalyzed ring-opening polymerization of propylene oxide effect of cocataiysts on polymerization behavior... 

Ouhadi T, Hamitou R, Jerome R, Teyssie P (1976) Soluble bimetallic p-oxoalkoxides. 8. Structure and kinetic behavior of the catalytic species in unsubstituted lactone ring-opening polymerization. Macromolecules 9 927-931... 

T. Uryu, K. Kitano, and K. Matsuzaki, Ring-opening polymerization of 5,6-anhydro-glucose and 5,6-anhydro-allose derivatives. Effect of substitution or configurational difference at the position of sugar monomers on polymerization behavior, J. Polym. Sci., Part A Polym. Chem., 20 (1982) 2181-2194. 

Heterobicyclic compounds often display specific behavior in their ring-opening polymerization. This is attributed to their rigid and bulky structures which contain, in most cases, two or more asymmetric carbon atoms. Sometimes, stereoelectronic effects involving heteroatoms also play an important role in regulating polymerization processes. For example, racemic bicyclic acetals such as 6,8-dioxabicy-clo[3.2.1]octane and its derivatives often undergo stereospecific polymerization even in the presence of conventional Lewis acid initiators. 

Spiro orthoesters (92, R = Me, Ph, and H) show typical equilibrium polymerization behavior at or below ambient temperature. [92] The poly(cyclic orthoester)s derived from 92 depolymerize to the monomers, although they have sufficient strains to be able to undergo ring-opening polymerization. The polymerization enthalpies and entropies for these three monomers were evaluated from the temperature dependence of equilibrium monomer concentrations (Table 5). The enthalpy became less negative as the size of the substituent at the 2-position in 92 was increased H < Me < Ph. This behavior can be explained in terms of the polymer state being made less stable by steric repulsion between the bulky substituents and/or between the substituent and the polymer main chain. The entropy also changed in a similar manner with the size of the substituents. 

Albertsson and coworkers [240-244] carried out extensive research to develop polymers in which the polymer properties are altered for different applications. The predominant procedure is ring-opening polymerization which provides a way to achieve pure and well defined structures. They have utilized cyclic monomers such as lactones, anhydrides, carbonates, ether-lactones. The work involved the synthesis of monomers not commercially available, studies of polymerization to form homopolymers, random and block copolymers, development of cross-linked polymers and polymer blends, surface modification in some cases, and characterization of the materials formed. The characterization is carried out with respect to the chemical composition and both chemical and physical structures, the degradation behavior in vitro and in vivo, and in some cases the ability to release drug components from microspheres prepared from the polymers. 

Although the pKa or H0 values for several acids are known [10,11], the definition of strong acid is somewhat arbitrary, because the position of equilibrium (13) depends on the basicity of heterocyclic monomer. Because this basicity varies from rather low (e.g., cyclic acetals) to rather high (e.g., cyclic amines) no universal rule describing the behavior of particular protonic acids in ring-opening polymerization exists. 

The consumption of cyclosiloxane during polymerization and copolymerization was monitored by GC. The conversion of D3 was nearly 100 % (Fig. 1). In contrast, the ring-opening polymerization of d/ yielded a conversion of about 60 % only (Fig. 2). During the copolymerization with D3 the cyclic vinylsiloxanes showed a similar behavior as observed during homopolymerization. 

Summary PDMS-6-PEO short-chain diblock copolymers were prepared via anionic ring-opening polymerization of cyclosiloxanes. Applying this method, various well-defined block copolymers with different compositions were synthesized and their phase behavior was investigated. The polymers predominantly showed lamellar phases in aqueous solutions. At small surfactant concentrations, vesicles were formed, as observed via cryogenic TEM. The aggregates of the diblock copolymers were used for the formation of lamellar thin films, applying the evaporation-induced self-assembly approach. 

Currently known initiation methods for ring opening pol)rmerization are reviewed in a systematic way with special emphasis on their influence on the properties of the resulting polymer. The importance of the chemical elements that comprise each group of initiators is demonstrated and it is shown that the behavior of the initiators is related to the position of these chemical elements in the Periodic Chart of the Elements. The ring opening polymerization of tetrahydrofuran is used as a model for the review. 

As a last example, we Illustrate the ring opening polymerization of octamethyltetraslloxane (D4) to yield polydlmethyl-slloxane. The linear polymer 1 Is the basis of both silicone oils at low molecular weights and silicone rubber at very high molecular weights (M, 3 500,000). Of course. In order to provide for vulcanization and enhance low temperature behavior, other units such as methyl-vinyl and possibly diphenyl are also Incorporated along the chain, as will be discussed later In this brief review and In... 

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