Poly ring-opening polymerisation

Stoessel [87] has reported using ultrasound to promote the ring opening of polycarbonate rings (Fig. 5.44) whilst Price [88] has studied the ring opening polymerisation of poly(dimethylsiloxane) (Fig. 5.45). Price found that in the presence of ultrasound, and the presence of sulphuric acid at room temperature, faster polymerisation rates and higher molar masses were obtained. 

The first ring-opening polymerisation of cycloolefin was reported shortly after discoveries by Ziegler and Natta Anderson and Merckling [40] claimed that the polymerisation of norbornene could be promoted by the TiCU—MgEtBr catalyst. The structure of the product, however, was not recognised immediately, but is now known to have been poly(l-vinylene-3-cyclopentylene) ... 

Subsequently, Eleuterio [41] filed a patent concerning the ring-opening polymerisation of cyclopentene leading to poly(l-pentenylene) ... 

Cycloolefins can be ring-open polymerised with a high degree of stereospecificity. Many poly(l-alkenylene)s prepared by metathesis polymerisation of cycloolefins are stereoregular polymers with presumably a cis or Irons configur-... 

Characteristic of these models of active sites is the appearance of the OZn O Zn(0)Et species. Considering the structural properties of the discussed catalysts as well as the polymer chain microstructure and the structure of the end groups of poly(propylene oxide) obtained with the PhOZnOCeHi ( -Bu)OZnEt catalyst, a concerted mechanism of epoxide ring-opening polymerisation with catalysts containing multinuclear species, including those with condensed zinc atoms, has been postulated [65,74] ... 

Methyl methacrylate polymerises in the solid state to give an amorphous poly(methylmethacrylate), as do a number of other methacrylate monomers. Poly(oxymethylene) is a fibrous, oriented, crystalline polymer that is obtained by the ring opening polymerisation of cyclic oxymethylenes, -(CH20)-m, where m can be between 3 and 6. 

Poly(methinimin) (-(HC=N)-) formation through cationic ring opening polymerisation of l,3,5-triazme >. 

Poly(amino acid)s (PAAs) have also been used in drug delivery PEO-(l-aspartic acid) block copolymer nano-associates , formed by dialysis from a dimethyl acetamide solution against water, could be loaded with vasopressin. PLA-(L-lysine) block copolymer microcapsules loaded with fluorescently labelled (FITC) dextran showed release profiles dependent on amino acid content. In a nice study, poly(glutamate(OMe)-sarcosine) block copolymer particles were surface-grafted with poly(A-isopropyl acrylamide) (PNIPAAm) to produce a thermally responsive delivery system FITC-dextran release was faster below the lower critical solution temperature (LCST) than above it. PAAs are prepared by ring-opening polymerisation of A-carboxyanhydride amino acid derivatives, as shown in Scheme 1. 

Another anionic ring-opening polymerisation that can also be used for the synthesis of a poly(germasilane) as well as a polysilane has been described by Sakurai and co-workers and is shown in Scheme 11.4. They are formed in greater than 40% yield and as well as having narrow molecular weight distributions (Mn = 17,000, Mw/M = 1.3) the polymers are highly ordered, as evidenced by NMR spectroscopy. 

The polymers (10.54) and (10.55) are closely related to the poly(alkylene phosphates) which can be made by ring-opening polymerisation (10.56) or by condensation of dialkyl phosphites (10.57). Molecular weights of over 10,000 have been achieved [38]. 

Following the development of PLGA, poly(e-caprolactone) (PCL) has been synthesised by ring-opening polymerisation and also developed as a degradable polymer. Other synthetic polymers based on hydroxyacids such as malic acid and its derivatives have been proposed. 

Figure 3.7 Synthesis of poly(dimethylsiloxane) (PDMS) by ring-opening polymerisation.

Moore, T., Adhikari, R. and Gunatillake, P. (June 2005). Chemosynthesis of bioresorbable poly(y-butyrolactone) by ring-opening polymerisation A review. Biomaterials, 26 (18), 3771-3782. 

The polymers are synthesised via two routes direct polycondensation of lactic and glycolic acids or ring-opening polymerisation of the cyclic lactide and glycolide dimers.The nomenclature for polymers prepared by different routes is full of contradictions, but polymers prepared from lactic acid by polycondensation are strictly referred to by the acid, as in poly(lactic acid), and those prepared by ring-opening polymerisation by the dimer, as in polylactide (PLA). ... 

Table 4.2 Properties of poly(trimethylene carbonate) of different molar masses obtained via ring-opening polymerisation...

Jugdaohsingh R, Anderson SH, Tucker KL, Elliott H, Kiel DP, Thompson RP, Powell JJ (2002) Dietary silicon intake and absorption. Am J Clin Nutr 75(5) 887-893 Li HL, Zhu Y, Xu D, Wan Y, Xia L, Zhao X (2009) Vapour-phase silanization of oxidised porous silicon for stabilizing composition and photoluminescence. J Appl Phys 105 114-307 Mclnnes SJP, Thissen H, Choudbury NR, Voelcker NH (2009) New biodegradable materials produced by ring opening polymerisation of poly(L-lactide) on porous silicon substrates. J Coll Interf Sci 332 336-344... 

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