PCL/PLLA

PCL, PLLA, or both were included. The a-CD-IC resulting from the suspension of PLLA-a-CD-IC in the PCL solution was found to contain only PCL guest chains, while the a-CD-IC resulting from the suspension of PCL-a-CD-IC in the PLLA solution contained only a very small amount of PLLA guest chains. The above results were interpreted to signify the importance of both guest polymer hydrophobicity and guest/host steric compatibility in the formation of polymer-CD-ICs. 

Fig. 20 X-ray diffractograms of pure PCL (a) and PLLA (b) and PCL/PLLA blends obtained by casting from dioxane solution (c) and hot water coalescence from PCL/PLLA-a-CD-IC (d) [12]...

Very recently Heise and Dubois reported the first example of the combination of enzymatic and chemical carbene-catalyzed ROP for the formation of block copolymers (Figure 12.10) [31], In their approach they took advantage of the fact that CALB has a high catalytic activity for lactones but not for lactides (LLA), while it is visa versa for carbenes. In the applied synthetic strategy the enzymatic polymerization of CL was conducted first. Addition of lactide and carbene to the reaction mixture lead to the macroinitiation directly from the hydroxyl end-group of PCL allowing the syhthesis of PCL/PLLA block copolymers. 

Scheme 1.21 Synthesis of a triblock copolymer PLLA-PCL-PLLA (as an example utilizing 1,6-hexandiol as the initiator for the ROP of CL).

Cardoso, G.B.C., 2011. Initial study of electrospinning PCL/PLLA blends. Advances in Materials Physics and Chemistry 01 (03), 94—98. 

Two different types of biodegradable pofyester composites, PLLA fibre-reinforced PCL and PCL/PLLA blend films, were prepared with a PCL/PLLA ratio of 88/12 (w/w) and their... 

Composite material consists of two or more materials that behave together to get the better properties of scaffold. Polymer/ceramics composite scaffolds are imitations of natural bone. Natural bone is made of HAP and organic collagen material and this HAP has better osteoconductivity. HAP, as the mineral part in the formation of composites and collagen, gelatin, chitosan, chitin, elastin, poly(methylmethacrylate), PPF, polyphosphazenes, PHB, poly(lactide-co-glycolide) (PCL, PLLA, PGA), PA, and POE, it can be the matrix phase for the bone replacement. 

The thermoplastic PCL-related bioelastomers were prepared as shown in Scheme 8.10, which were poly(L-lactide)-PCL (PLLA-PCL) multiblock copolymers.The bischloroformates of carboxylated PLLA were first synthesized mainly by two steps, preparing PLLA diols initiated by 1,6-hexanediol with starmous octoate as catalyst at 130 °C for 5 h, and synthesizing acylhalide (COCl) group terminated PLLA at 60 °C for about 3 h from dicarboxylated PLLA which was prepared from PLLA diol and succinic anhydride. Then,... 

Goonoo N, Bhaw-Luximon A, Rodrignez lA, Wesner D, Schbnherr H, Bowlin GL, Jhurry D. Poly(ester-ether)s III. assessment of cell behaviour on nanofibrous scaffolds of PCL, PLLA and PDX blended with amorphous PMeDX. J Mater Chem B 2015 3 673-687. 

Figure 11.4 compares the X-ray diffractograms of pure PCL and PLLA and their blends obtained by casting from their dioxane solution and by the hot water coalescence from their common IC with a-CD. Note that diffraction peaks from both PCL and PLLA crystals are prominent in the solution-cast blend (Fig. 11.4c), indicating a highly phase-separated morphology. On the other hand, in Fig. 11.4d the diffractogram of the PCL/PLLA blend coalesced from their common a-CD-IC, no diffraction peaks are observed for PCI crystals and only very weak peaks are observable for PLLA crystals. In fact, from DSC observation of the coalesced PCL/PLLA blend, it is estimated that no PCL crystals are present, and that only 5% of the PLLA is crystalline. Clearly then, the coalesced PCL/PLLA blend appears to be nearly totally amorphous and presumably well-mixed. 

Two-dimensional solid-state spin-diffusion Hetcor NMR experiments revealed that the coalesced PCL/PLLA blend was intimately mixed. The average minimum dimension for the amorphous coalesced PCL/PLLA blend was 4.9nm, versus 7.4nm for the amorphous regions of the semicrystalline PCL/PLLA blend prepared by dissolution in dioxane. The former dimension is comparable to the 4-5 nm radii of gyration for the particular PLLA and PCL polymers used, indicative of molecular level mixing in the coalesced... 

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