The performance of polymeric structures as drug delivery systems and implantable devices is fully dependent on their stability and integrity in biological environments. The Layer-by-Layer (LbL) technology is a versatile technique that can be used to fabricate numerous structures such as planar ultrathin films and membranes, without using aggressive solvents. LbL relies on the use of polyelectrolytes with an opposite charge assembled onto very thin (few nm) or large (several tens of μm) structures. The nature of polymer interactions makes the assembly a versatile plat form to load and release macromolecules. The deposition of hundred layers of biopolymers (polysaccharides) on a low energy substrate (polypropylene) led to the production of a thick free-standing membrane with tenable thickness (tens of μm) and mechanical properti es. For example, these membranes were able to drive bone generati on in vivo after loading with the oestrogenic factor BMP-2. LbL free-standing membranes could be produced with various biopolymers (hyaluronic acid, collagen…) and deliver bio macromolecules such as proteins or nucleic acids or even Nano objects for skin or mucosal applications.

Graphene has received extensive attention and wide application in electrical device, energy materials, and biomaterials, due to its large surface area and excellent performance in mechanical, thermal conductive, electrical and optical properties. All the properties depend on the distinct structure of graphene, such as layers, scale, surface defects. However, the difficulty of fast and efficient preparing high-quality graphene limits its industrial applicati on. In this study, a conjugated IL named 1-methyl-3-pyrenemethylimidazolium hexafluorophosphate ([MPIM][PF6]) was synthesized and used to exfoliate graphite into grapheme with the assistance of microwave irradiation. Owing to the cation-π interaction and additional strong π-π interaction between [MPIM][PF6] and graphite, large-scale, defect free and few-layer high-quality graphene (GNPIL) was efficiently prepared. And the results show that a relatively high yield of 40% is obtained. Moreover, the GNPIL has good dispersability and conductivity due to the presence of ionic liquids in the interlayer. The high-quality GNPIL could be dispersed in organic solvent homogeneously and stably with a high content, which is beneficial for its further applications. The AFM results show that the ionic liquid-functionalized graphene has a thickness of 4 to 6 nm and 5 to 10 layers. FTIR curves further prove ionic liquids exist in the graphene sheets. UV-Vis is used to characterize the dispersibility of the graphene in the organic solvent. Furthermore, this GNPIL is used to improve the conductivity and mechanical property of polymer. Compared with the resistivity of pure polymer, the resistivity of the composites decreases by eleven orders of magnitude, when 0.75 wt% graphene is added. With the increase of graphene content, the tensile strength of the composites increases gradually and when the content is 0.75 wt%, the tensile strength reaches the maximum, after that, it decreases. However, the thermal properties of composites do not change too much after the addition of graphene, so the composite still maintains good thermal properties.

The aim of this study was to produce the bio plastic packaging from banana pseudo-stem (Musa spp.cv. Nam-Wah). The cellulose of banana pseudo-stem was extracted with sodium hydroxide and then lignin removed with hydrogen peroxide. The cellulose powder was then synthesized to biopolymer: carboxymethyl cellulose (CMC) by chloroacetic acid in alkaline condition. The percent yield of cellulose from banana pseudo-stem was 20.25% whereas the yield of CMC was 140.89%. The obtained CMC powder had 95.33% purity and a degree of substitution (DS) at 0.768. It was water soluble with low viscosity at 114 cPs and appeared in pale yellow color. CMC solutions were added with 3 different additives viz. glycerol, sorbitol and polyethylene glycol at 10, 20, 30 and 40% (w/v) concentrations to form bio plastic film. The higher content of all additives resulted to the thicker film, greater elongation (%), poorer water solubility and lower tensile strength. Film without any additives had the highest tensile strength. The films formed with 40% sorbitol had the highest elongation while oxygen could transmit through film with 40% polyethylene glycol at greater rate than other films. Besides, films with 10% glycerol had the highest water solubility. All CMC-based bioplastic films could be degraded within 24 hours by burying it in high moisture content soil. Adwerward, CMC films were processed to sachets for storing dry coffee powder. CMC-20% polyethylene glycol sachets could maintain quality of dry coffee powder if stored in refrigerated condition whereas CMC-30% polyethylene glycol could retain quality of dry coffee as similar as the coffee packed in aluminium foil bags at ambient air. The results indicated that bio plastic derived from the pseudo stem of banana could be a potential material for dry food packaging.

Single-stranded DNAs with specific sequence not only effectively disperse single walled carbon nanotubes (SWCNT), but also enable chiral separation of SWCNT, but their sorting mechanism has not been clarified yet. Here, we chose SWCNT (6,5) and single-stranded DNA (GT)20 as an example, DNA-SWCNT hybrids were prepared and their structures were characterized. Quantitative measurements of intermolecular forces in DNA-SWCNT hybrids were conducted at different salt concentrations by using osmotic method in combination with X-ray diffraction. Data analysis showed that the intermolecular forces of DNA-SWCNT hybrids could be well described by using long-range electrostatic repulsion and short-range hydration repulsion at low salt concentrations; while at high salt concentrations, non-electrostatic attractions were observed, which we think were attributed to the hydrophobic interactions of exposed SWCNT surface. This study not only helps us understand DNA conformation on SWCNT surface as well as their sorting mechanism of SWCNT, but also has great significance in the assembly of SWCNT-based functional materials.

“BigBags”, made of stretched standard polymer tapes (e.g. iPP, PE-HD, PET, and PA), are suitable packaging materials with the required mechanical properti es for heavy loads, e.g. fertilizers in agricultural applications. Based on environmental aspects, synthetic highlystretchable polymer tapes should be replaced by resourcesaving Biopolymer tapes with high-strength properti es. Thus, the goal of this study was to avoid polymer-waste, especially in agricultural applications. It is known that linear, unbranched polymer chains allow for a high stretchability, but unfortunately Biopolymers usually have a more complex structure compared to synthetic polymers. Until now no Biopolymer-compounds with high-strength properties are known and basic know-how about correlations between stretching parameters and materials properti es is very scarce, especially for Biopolymers. Compounds of starch and Biopolyesters are promising materials for production of biodegradable products, because of their availability, renewability and biodegradability. However, compared to stretchable films made of synthetic polymers elongations at break of starches are lower by a factor of 100. Plasticizers are used to increase fl exibility and stretchability of starch. Starch compounded with plasticizers is termed “thermoplastic starch” (TPS). The most common plasti cizer is glycerol, which reduces the intermolecular bonding forces by increasing the inter(macro)molecular distance. In this study the influence of different starch pre-treatments (e.g. acid degradati on) and starch sources (potatoe, maize etc.) to the strechability and mechanical properties were investigated. The aim was to develop high-strength TPS-Bio polyester-compounds, which allow for a high stretchability and stiff ness as required in BigBag-applicati ons. Furthermore, correlations between material properti es and stretching parameters of Biopolymer-compounds were evaluated. It was found that parameters, such as sample geometry, temperature, degree, as well as velocity of stretching have an infl uence on mechanical properti es. Thick and narrow samples, higher temperatures and lower velociti es of stretching result better mechanical properties. Ultimately, results indicate that the degree of stretching should be lower than 100%.