Macrocyclic poly polymerizations

The polymerization of lactones with tin alkoxides is thought to follow the co-ordination-insertion mechanism[77a]. The ring-opening of the monomer proceeds through acyl-oxygen cleavage with retention of the configuration. Tin(IV) complexes have been used to produce predominantly syndiotactic poly((3-hy-droxybutyrate) [78,79],macrocyclic poly((3-hydroxybutyrate) [80],poly(e-CL), and polylactide [77,76,81]. 

Zolotukhin et al. have prepared the macrocyclic poly(arylene thioether ketone) 113 to study ring-opening polymerization <2004MM2041>. Compound 113 was prepared by the reaction of 4,4 -bis(4"-fluorobenzoyl)diphenyl ether with 4,4 -thiodiphenol in iV,iV-dimethylacetamide under a high dilution condition in a poor 9% yield. Structure of 113 was confirmed by X-ray analysis. 

Kricheldorf, H. R., Langanke, D., Spickermann, J., and Schmidt, M., Macrocydes. 10. Macrocyclic Poly(l,4-butanediol-esters)s by Polycondensation of 2-Stanna-1,3-dioxepane with Dicarboxylic Acid Chlorides, Macromolecules, 32,3559,1999. Jedlinshi, Z., Juzwa, M., Adamus, G., Kowalczuk, M., and Montaudo, M., Anionic Polymerization of Pentadecanolide. A New Route to a Potentially Biodegradable Aliphatic Polyester, Macromol. Chem. Phys., 197, 2923,1996. 

Macrocyclic oligomer precursors of polycarbonates, PET, polymers of amides, etherketones, and ethersulfones are candidates for further study of macrocyclic oligomer polymerization thermodynamics [6]. Research extends to cyclic arylates (cyclic aryl-aryl esters) and cyclic alkyl aryl esters going back to isolating a cyclic trimer of poly(ethylene-terephthalate) in 1954 [13]. Much of the work on macrocyclic oligomers as precursors to high-MW macromolecules starts with spiro(bis)indane (SBI) biphenyl monomer to produce macrocyclic carbonates. 

Method 2. Reequilibration of Cyclic Dimethylsiloxanes Recent evidence supports the presence of macrocyclic poly(dimethylsilox-anes) in dimethyl silicone polymers (22,23,31). In what is really a ring-opening followed by a ring-forming polymerization, octamethylcyclotetrasiloxane was heated with traces of potassium hydroxide with or without a diluent and chain-stopped with trimethylchlorosilane/pyridine. 

A change of architecture is another route that enables diversification of the properties of aliphatic polyesters. This review will focus on star-shaped, graft, macrocyclic, and crosslinked aliphatic polyesters. It must be noted that the ROP of lactones has been combined with several other polymerization mechanisms such as ROP of other heterocyclic monomers, ionic polymerization, ROMP, and radical polymerization. Nevertheless, this review will not cover these examples and will focus on polymers exclusively made up of poly(lactone)s. 

A closely related special case of metathesis is the conversion of cycloalkenes under metathesis conditions, known as ring-opening polymerization or metathesis polymerization (see Section 12.2). Macrocyclic polyenes and polymers, called poly-alkenamers, are formed with high stereoselectivity ... 

This type of ring expansion polymerization was extended for a synthesis of multiblock copoly(ether-ester)s of poly(THF) and e-caprolactone with cyclic dibutyltin initiators [142]. Such ring expansion polymerizations of lactones to synthesize macrocyclics with spirocyclic tin initiators are shown in Fig. 42 [143],... 

Zhang, D., Hillmyer, M.A. and Tolman, W.B. 2004. A New Synthetic Route to Poly[3-Hydroxypropionic Acid] (P[3-HP]) Ring-Opening Polymerization of 3-HP Macrocyclic Esters. Macromol., 37, 8198-8200. 

Macrocyclics from CO and COD Polymers. High molecular weight polymer samples, prepared in the CO and COD polymerizations and extracted to remove their respective low molecular weight macrocyclic fractions were dissolved in dried benzene forming a 4% solution of poly-octenamer and also one of poly-1,5-octadienamer. 

Figure 9. NMR spectra of poly-1,5-octadienamer, extractable macrocyclic fraction from poly-1,5-octadienamer, and poly-1,5-octadienamer obtained by polymerization of the extractable macrocyclic fraction...

Main-chain poly(styrene rotaxane)s <1997MM337, 1999PLM1823> were obtained by free radical polymerization of styrene in the presence of crown ethers using initiators incorporating bulky blocking groups to prevent dethreading of the macrocyclic components. 

It is important in the cyclization process to maximize the yields of the desired macrocycle by choosing strategies that inhibit the competing linear polymerization reaction. Since the reactants for both cyclization and poly-... 

In the polymerization of propylene sulfide and 1,2-butylene sulfide mainly tetra-mers were observed. Cycles were formed mostly during the slow degradation process that followed rapid polymerizations. Degradation can also be induced by adding cationic initiators to polymer prepared by other mechanisms, e.g. by anionic processes. Thus, poly(trans-2,3-butene sulfide) is rapidly degraded to equimolar amounts of 3,5,6,7-tetramethyl-l,2,5-trithiacycloheptane and trans-butene 47). Poly(cis-2,3-butene sulfide) forms, however, a mixture of tetramer, trithiacycloheptane derivative and cis-butene 47 . If one is forced to use cationic processes for the synthesis of poly-sulfides, the reaction conditions should be controlled to avoid macrocyclization. If cyclic products are desired, the kinetics of their formation should be studied to determine optimum yields. 

A. Ben-Haida, H. M. Colquhoun, P. Hodge, and D. J. Williams. Synthesis of a catechol-based poly(ether ether ketone) ("o-PEEK") by classical step-growth polymerization and by entropically driven ring-opening polymerization of macrocyclic oligomers. Macromolecules, 39(19) 6467-6472, September 2006. 

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