Crystallization and stereocomplexation governed self‐assembling of poly(lactide)‐b‐poly(ethylene glycol) to mesoscale structures

Abstract

The stereocomplex formation between enantioselective poly(lactide) (PLA) homopolymers is well understood. In this report an attempt is made to analyze the influence on the self‐assembling of the stereocomplex of enantiomorphic PLA‐PEG di‐ and tri‐blocks in different solvents. Powder diffraction studies showed the poly(ethylene glycol) (PEG) and the PLA blocks crystallize separately forming unique supra structures like rods, discs and coiled coils with dimensions in the micrometer scale in length and sub‐micrometer scale in diameter. The influence of the solvents on the crystal formation was shown in the formation of uniform structures. Discs emerged from equimolar mixtures of the D‐ and L‐configured di‐ and tri‐block copolymers, in dioxan and acetonitrile and in water the stereocomplexes crystallized mainly as rods. In some cases the rods were observed as coiled coils. The shape, the hydrophobic/hydrophilic content and the PEG coated surface of the discs give them a future potential as matrix for the controlled and targeted delivery of bioactive agents. Copyright © 2005 John Wiley & Sons, Ltd.

Heterostereocomplexes Prepared from d-Poly(lactide) and Leuprolide. I. Characterization

“…Although crystal structures depend very much on the way of sample preparation, disc-shape crystals are commonly found in stereocomplexes of both homo and block copolymers of D-and L-PLA. 17 Application of only leuprolide solution on mica did not lead to recognizable pattern formation.…”

Crystallization and stereocomplexation behavior of poly(D‐ and L‐lactide)‐b‐poly(N,N‐dimethylamino‐2‐ethyl methacrylate) block copolymers

“…For low molecular weight samples, the particles have a disk‐like form. The morphology of the stereocomplexes depends on the molecular weight, concentration of the solution, temperature, evaporation rate of the solvent and DL/LL ratio 36, 37, 40, 42–44…”

“…The morphology of the stereocomplexes depends on the molecular weight, concentration of the solution, temperature, evaporation rate of the solvent and DL/LL ratio. 36,37,40,[42][43][44] FIGURE 8 DSC heating scans at 20 C/min for the PLA/PLA-b-PDMAEMA stereocomplexes indicated.…”

Characterizing Biodegradation of PLA and PLA‐g‐AA/Starch Films Using a Phosphate‐Solubilizing Bacillus Species

“…[6] Recently, plasticizers such as poly(ethylene glycol) (PEG), glucose monoesters and partial fatty acid esters have also been used to improve the flexibility and impact resistance of PLA. [7,8] In this study PLA, as the core matrix, was blended with starch, an abundant, inexpensive, renewable and fully biodegradable natural raw material, to modify its physical properties including biodegradability, permeability and mechanical strength. The hydrophilic character of starch leads to poor adhesion with the hydrophobic polymer in starch-polymer blends and such blends therefore require a compatibilizer and/or a toughener, with a reactive functional group introduced into the synthetic polymer, to enhance the compatibility between the two immiscible phases and hence to improve the mechanical properties of the composite.…”