Preparation and characterization of bio-based materials from polysaccharides and derivatives.

摘要

Nowadays, various bio-based materials have attracted increasing interest in different areas such as drug delivery, gene therapy, automobile, packaging, etc. The current thesis work focuses on the preparation of bio-based materials from polysaccharide or its derivatives due to their wide abundance, biocompatibility, biodegradability, and low cost. According to their end applications, three types of polysaccharides (derivatives) are selected, including beta-cylclodextrin (beta-CD), cellulose microfibrils (CMF), and starch. In the first part of the study, a novel water-soluble cationic diblock polymer, CD-PAM-b-PMeDMA, was synthesized via atom transfer radical polymerization (ATRP) using esterification modified beta-CD as a macro-initiator. The polymerization conditions for both the first and second block were optimized, and the resulting diblock cationic star polymers are of great potential as non-viral gene vectors. The second part of the study investigated the surface-initiated ATRP (SI-ATRP) of butyl acrylate (BA) on CMF to create controllable hydrophobic chains on CMF. The optimum polymerization conditions were achieved by considering the effects of several parameters including types of solvents, reaction temperature, and the catalyst systems. In the third part, poly (butyl acrylate) (PBA) with different chain lengths was immobilized on CMF through SI-ATRP under the optimum conditions, which were conducting the polymerization in tolulene at 90 °C using N,N,N',N',N"-pentamethylethylenetriamine (PMDETA) as the ligand, obtained from the second part of the study, the thermal stability and hydrophobicity of resulting modified CMF (CMF-PBA) were increased compared to those of the original CMF. The biocomposites, prepared by melt blending CMF-PBA and polypropylene, presented increased interfacial adhesion and mechanical properties with the increase of molecular weight of PBA grafts. In the fourth part of the study, compatibilized Poly(butylene adipate-co-terephthalate) (PBAT)/thermoplastic starch (TPS) blends were prepared using modified PBAT as the compatibilizer. The compatibility, TPS dispersion, and tensile properties of the resulting blends were significantly enhanced compared with the unmodified blends. The last part of the study focused on the preparation of compatibilized composites using talc as functional filler in an attempt to further increase the TPS contents in film products. The presence of an appropriate amount of talc (approximately 3 wt%) facilitated the blown filming process even if the TPS content was as high as 50 wt%. The overall performance of PBAT/TPS/Talc composites was also better than that of PBAT/TPS blends, including better thermostability, improved compatibility, enhanced mechanical properties, and so forth.