Abstract
Polylactide (PLA) latex particle covered with polypeptide chains were prepared by means of solvent exchange method from PLA and PLA-block-polypeptide block copolymer solutions. PLA segment of the block copolymer and PLA homopolymer formed a core of the particle, and the polypeptide segment of the block copolymer, which is designed as tightly fixed biodegradable emulsifier, formed corona around the particle surface. This picture was supported by the fact that zeta-potential of PLA latex particle covered with polypeptide segment was different from that of bare PLA particle because of the presence of the ionizable group in the polypeptide chains. To clarify the effect of the ionizable group on conformation of the polypeptide chain, the relation between the polypeptide chain length and the area occupied by the single block chain was evaluated. The result that the occupied area per a polypeptide chain was linearly increased with the increase in the polypeptide chain length indicates that the polypeptide chains trail on the particle surface and did not take helical structures.
Highlights
To control global warming, it is important to convert a source of energy and raw materials in various industries to the biomass from the petroleum
PLA latex particle was prepared from PLA homopolymer and PLA-block-poly(L-lysine) block copolymer by the solvent exchange method as shown in Figure 1 [7]
Morphological observation of latex particles was performed with a scanning electron microscope (SEM) (VE-9800, Keyence Corporation, Japan)
Summary
It is important to convert a source of energy and raw materials in various industries to the biomass from the petroleum. Polylactide and polypeptide are the biomass-originated materials, which are obtained from polymerization of lactic acid or amino acid. They are known as biocompatible and biodegradable materials. We have paid attention to PLA latex dispersions since a brand-new style of PLA materials should be necessary to expand the applicable field. Amphiphilic block copolymers, PLA-blockpolypeptide, were synthesized from PLA and hydrophilic polypeptide, and their application to a biodegradable surfactant was examined. The surfactant was used to stabilize a PLA latex dispersion since it had biodegradable and biocompatible characteristics. The PLA-block-polypeptide and the PLA homopolymer were self-organized with a solvent exchange method [7] in order to anchor the hydrophilic polypeptide chains which were the source of surface stabilization. We discussed the conformation of polypeptide chain which was grafted on the surface of latex particle and which have determined the stability of the latex dispersion
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