Nanoparticles from renewable polymers

Abstract

The use of polymers from natural resources can bring many benefits for novel polymeric nanoparticle systems. Such polymers have a variety of beneficial properties such as biodegradability and biocompatibility, they are readily available on large scale and at low cost. As the amount of fossil fuels decrease, their application becomes more interesting even if characterization is in many cases more challenging due to structural complexity, either by broad distribution of their molecular weights (polysaccharides, polyesters, lignin) or by complex structure (proteins, lignin). This review summarizes different sources and methods for the preparation of biopolymer-based nanoparticle systems for various applications.

Keywords: biodegradation; formulation of nanoparticles; nanoparticles; polymers.

Figure 1

Dextran as an example of a branched polysaccharide with multiple hydroxyl groups as functional moieties.

Figure 2

Schematic synthesis of poly(lactic acid) from lactide.

Figure 3

Structure of poly(lactic acid-co-glycolic acid).

Figure 4

Schematic representation for the preparation of lignin nanocapsules (image taken from Yiamsawas et al., - Published by The Royal Society of Chemistry).

Figure 5

Schematic representation of the polymeric Ouzo-effect. A polymeric solution is added to water. Nanophaseseparation leads to polymeric nanoparticles.

Figure 6

Schematic representation of miniemulsion polymerization. Stable droplets in the range of few hundreds of nanometers are generated by the addition of a costabilizer (light green) and homogenization by ultrasound. The monomer droplets act as nanoreactors.

Figure 7

Schematic representation of the solvent evaporation process. A polymer solution is formulated as a surfactant stabilized emulsion. Subsequently the solvent is evaporated resulting in polymeric nanoparticles.

Figure 8

Schematic representation of classic emulsion polymerization.

Figure 9

Schematic representation of microemulsion polymerization. Radical polymerization in very highly concentrated surfactant/co-surfactant solution leads to ultrasmall polymeric nanoparticles.

Figure 10

Schematic representation of interfacial reactions in inverse emulsion. One monomer (purple) is provided in the aqueous droplets, the other one (light green) is added, dissolved in solvent. The reaction leads to a polymeric shell enclosing the water droplets.