Conventional and microwave-assisted synthesis of hyperbranched and highly branched polylysine towards amphiphilic core–shell nanocontainers for metal nanoparticles

• Published in: Polymer (Guilford) Vol. 53; no. 21; pp. 4623 - 4630
• Main Authors: Ho, Chau Hon, Thiel, Matthias, Celik, Seref, Odermatt, Erich K., Berndt, Ingo, Thomann, Ralf, Tiller, Joerg C.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 28.09.2012; Elsevier
• Subjects: Aminoacid polymers; Applied sciences; chloroform; coatings; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; heat; Hyperbranched polymer; Materials science; medicine; microwave treatment; molecular weight; nanocrystals; Nanoparticles; Nanopowders; Nanoscale materials and structures: fabrication and characterization; Physicochemistry of polymers; Physics; Polylysine; polymers; salts; solvents; Synthetic biopolymers; toluene; Nanoparticles; Polylysine; Hyperbranched polymer; Molecular structure; Self condensation; Nanoparticle; Lysine polymer; Amidation; Chemical reduction; Aliphatic polymer; Acyl chloride; Microwave irradiation; Chemical synthesis; Amphiphilic polymer; Gold; Solution polycondensation; Branched polymer; Experimental study; Metal particle; Aminoacid polymer; Organic solution; Silver; Chemical modification; Preparation; Epoxide; Soluble compound; Mineral salt
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/j.polymer.2012.08.032

Hyperbranched amphiphilic polymeric systems with core–shell architecture can be used as versatile nanocontainers and templates with great potential in application fields ranging from medicine to organic coatings. In order to explore an alternative to the already widely used and established synthetic macromolecules, we synthesized new polymers based on hyperbranched polylysine. Polylysine was prepared with classical heating and microwave-assisted heating, respectively. While, the synthesis at 160 °C resulted in hyperbranched polylysine with degrees of branching (DB) between 0.50 and 0.54, the microwave-assisted heating at 200 °C resulted in highly branched polymers with DB values of 0.30–0.32. The molecular weight Mn could be controlled in a range of 5000–12,000 g/mol. The hyperbranched polylysine was hydrophobized via polymer-analogue reactions using a mixture of stearoyl/palmitoyl chloride and glycidyl hexadecyl ether, respectively. These reactions yielded in high degrees of modification (80% and 90%, respectively). The synthesized polymers are soluble in non-polar organic solvents, such as toluene and chloroform, and take up metal salts to up to 25 wt.%. They support the formation of Ag, Au, and Pd nanoparticles and nanocrystals in organic solvents and stabilize them. Thus, the here presented macromolecules are a promising readily achievable alternative to existing core–shell systems. [Display omitted]