L-Lactide, polymerization

Fig. 3 Bis(phenolate)-supported dimeric lithium and potassium L-lactide polymerization initiators [36-43]...

Fig. 13 Calcium complexes supported by N,0-donor Schiff base ligands Table 4 Ca complexes in rac-lactide and L-lactide polymerization...

A series of bis(thiophosphinic amido) yttrium complexes 86a-h was promising due to their high rates and enhanced control of the L-lactide polymerization activity with high polymerization rates A app = 2.2 x lO to 1.1 x 10 s at [LA]q = 1 M, [l]o = 5 mM [104]. It is worth noting that the phosphorous substituents greatly influenced the rate of the reaction, and that the rate followed the order isopropyl > phenyl > ethoxy. 

Biocidal polymers are considered to be the next generation of antibiotics which can be effectively used against microbial infections. The antimicrobial activities of silver-bearing functionalised polymers and L-lactide polymeric NP are an important aspect in the prevention of bacterial skin and urinary tract infections. Biologically derived compounds, such as bacteriocins, phytochemicals and enzymes, can be used in antimicrobial food packaging. 

Again, tri(alkoxide)s are more active than alkyl aluminium alkoxides. Even at the elevated temperatures used the propagation rate constants for L-lactide polymerization are low compared to e-caprolactone polymerization... 

Duda, A., and Penczek, S., 1990, Thermodynamics of L-Lactide Polymerization. Equilibrium Monomer Concentration. Macromolecules, 23 1636... 

Duda, A. Penczek, S. Thermodynamics of L-lactide polymerization. Equihbrium monomer concentration. MacromofecMfe 1990, 23, 1636-1639. 

Sosnowski S, Lewinski P. L-lactide polymerization catalysed by tin(II) 2-ethyl-hexanoate. A deeper look at chain transfer reactions. Polym Chem 2015 6 6292-6. 

Figure 12 Al NMR (75 MHz Al, 70 X, benzene-dg) spectra of the aluminum triisopropoxide trimer (A3) and the living polyesters prepared with A3, (a) A3 (b) living poly(8-caprolactone) (c) living poly (y-butyrolactone) and (d) living poly(L-lactide). Polymerization conditions (concentrations in molM) 3[A3]q = 0.1, [CL]o = 2.0, [y-BL]o = 3.8,...

Figure 17 Dependences of MJM on ([M]o-M])/[M]o determined for L,L-lactide polymerization initiated with (0) BusSnOEt, (V) Fe(0Et)3,...

Poly(dimethylsiloxane) and poly(ethylene oxide) macromonomers were commercial products.PCL macromonomer was obtained in reaction of the terminal hydroxyl end-groups of PCL with methacryloyl chloride. Poly(D,L-lactide) methacrylate was obtained by using 2-hydroxyethyl methacrylate as an initiator of the D,L-lactide polymerization and stannous acrylate as a catalyst. 

Braided Synthetic Absorbable Sutures. Suture manufacturers have searched for many years to find a synthetic alternative to surgical gut. The first successful attempt to make a synthetic absorbable suture was the invention of polylactic acid [26023-30-3] suture (15). The polymer was made by the ring-opening polymerization of L-lactide [95-96-5] (1), the cycUc dimer of L-lactic acid. 

Coordination numbers ranging from five to seven were observed, and they appeared to be controlled by the steric bulk of the supporting amidinate and coligands. Complexes 2-5 and 7 were found to be active catalysts for the pol3uneiization of D,L-lactide (e.g., with 2 and added benzyl alcohol, 1000 equiv of D,L-lactide were polymerized at room temperature in <1 h). The neutral complexes 2, 5, and 7 were more effective than the anionic complexes 3 and 4. ... 

Polymerization of D,L-lactide to polylactide was also achieved using monomeric tin(ll) amidinates (cf. Schemes 48 and and the mono... 

Recently, Cohn and Salomon synthesized and characterized a series of PLCL thermoplastic bioelastomers by two-step synthesis procedure. First, ring-opening polymerization of L-lactide initiated by the hydroxyl terminal groups of the PCL chain. Second, chain extension polymerization of these PLA-PCL-PLA triblocks initiated by the hexamethylene diisocyanate (HDl). 

Dittrich, V. W., and Schulz, R. C., Kinetics and mechanism of the ring-opening polymerization of L-lactide, Angew. Makro-mol. Chem.. 15. 109, 1971. 

Zhu, K. J., Xiangzhou, L., and Shilin, Y., Preparation and properties of D,L-lactide and ethylene oxide copolymer A modifying biodegradable polymeric material, J. Polym. Sei. Part C Polvm. Lett.. 24, 331-337, 1986. 

Anionically prepared hydroxy-terminated PBd was reacted with AlEt3 to form the corresponding aluminum alkoxide macroinitiator, capable of initiating the polymerization of L-lactide [117]. Using ratios [PBd-OH]/[AlEt3] between 1 and 6, reaction temperatures between 70 and 120 °C and maintaining the conversion of the lactide polymerization below 90%, products with narrow molecular weight distribution were obtained. 

Free radical polymerization combined with anionic ring polymerization was employed for the synthesis of poly(N-vinylpyrrolidone)-fr-poly(D,L-lactide), PVP-fr-PDLLA, as shown in Scheme 49 [121]. The free radical polymerization of VP was conducted using 2,2/-azobis[2-methyl-M-(2-hydroxyethyl)propionamide] as the initiator, isopropyl alcohol and 2-... 

By using a combination of RAFT and ring opening polymerization (ROP), (polyethylene oxide) methyl ether)(polystyrene)(poly(L-lactide) 3-miktoarm star terpolymers have been successfully synthesized [182]. The synthetic approach involved the reaction of the cw-functionalized - OH group of the poly(ethylene oxide) methyl ether with maleic anhydride under conditions where only one hydroxyl group can be esterified (MPEO). The double bond... 

Ag(carbene)2][AgCl2] (carbene = l,3-dimesitylimidazol-2-ylidene) Was also reported for use as a pre-catalyst for the polymerization of L-lactide with low PDI and in the absence of monomer racemization.69... 

Jensen et al. reported the stereoselective polymerization of D,L-lactide with dibenzyloxidezinc(2,4,6-trimetylphe-nyimidazol-2-ylidene), which was synthesized as shown in Scheme 39.100 Surprisingly, a mixture of the heterocarbene and benzyl alcohol was a better catalyst for polylactide formation than the zinc complex, and unlike 50 the mixture produced heterotactically enriched polylactide. 

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