Journal of Polymers and the Environment

This paper describes an ecofriendly development of a nanodrug delivery vehicle from seed oil. The entire synthesis, starting from the ZnO nanoparticle to the polymeric vehicle is purely microwave assisted with minimal usage of organic solvents. Multifunctional features like enhanced UV absorbance, antimicrobial properties and appreciable in vitro release can be attributed to the nanoparticle loaded polymeric vehicle. Characterization of the synthesized species was done through FT-IR, 1HNMR, SEM and XRD. The physical characterizations were carried out using conventional laboratory techniques.

Microcrystalline cellulose, cellulose nanocrystals (CNC), calcium carbonate nanoparticles, hydrophilic nanoclay and hydrophobic nanoclay, were separately added as fillers to konjac glucomannan, hydroxypropyl methylcellulose, and zein to investigate their effect on tensile properties of nanocomposite films. DMA results on biopolymer films confirmed significant differences between neat polymers due their different molecular weight and chemical structure. Fillers, at 2% load (w/w), affected film properties depending on their size, shape, and surface chemistry. Good dispersibility and the extent of polymer-filler interactions controlled the effect of nanofillers on film properties. Hydrophilic nanoclay and CNC better interacted with biopolymer matrices.

Eugenol (E) based mono-functional benzoxazine(E-x) monomers were prepared using different long-chain monoamines(x = ba, ha, dda, oda) and fluorine substituted aromatic monoamine (x = fa). The molecular structure of the monomers developed was characterized by FTIR and NMR spectral analysis. Further, the prepared monomers were coated over the cotton fabric and studied for their surface behavior. The poly(E-dda) coated cotton fabric exhibits the higher value of water contact angle (WCA = 151°) than that of other samples coated with polybenzoxazines(E-ba, E-ha,E-oda, and E-fa). Furthermore, poly(E-dda) coated cotton fabrics also displayed the lower value of surface energy of 15.6 mN/m with a lower sliding angle value(11°) than those of other coated cotton fabric samples. The formation of rough surfaces on the fabric was ascertained from microstructure analysis and thereby contributes to superhydrophobicity along with pH robustness. Subsequently, the oil-water separation efficiency and flux of the poly(E-dda) coated cotton fabric was found to be 98% and 5800 L/m2h respectively. It was also observed that the specimen of a glass substrate coated with poly(E-dda) exhibited the delayed ice formation. Data obtained from different studies, it is suggested that the eugenol-dodecylamine(E-dda) based benzoxazine can be effectively employed as an alternate to fluorine-based polymers.

Development of biodegradable polymers from absolute environmental friendly materials has attracted increasing research interest due to public awareness of waste disposal problems caused by low degradable conventional plastics. In this study, the potential of incorporating natural rubber latex (NRL) into chemically modified sago starch for the making biodegradable polymer blends was assessed. Native sago starch was acetylated and hydroxypropylated before gelatinization in preparing starch thermoplastic using glycerol. They were than casted with NRL into biopolymer films according to the ratios of 100.00/0.00, 99.75/1.25, 98.50/2.50, 95.00/5.00, 90.00/10.00 and 80.00/20.00 wt/wt, via solution spreading technique. Water absorption, thermal, mechanical, morphological and biodegradable properties of the product films were evaluated by differential scanning calorimetry (DSC), universal testing machine (UTM), scanning electron microscopy (SEM) and fourier transform infrared spectroscopy. Results showed that acetylation promoted the incorporating behavior of NRL in sago starch by demonstrating a good adhesion characteristic and giving a uniform, homogenous micro-structured surface under SEM observation. However, the thin biopolymer films did not exhibit any remarkable trend in their DSC thermal profile and UTM mechanical properties. The occurrence of NRL suppressed water adsorption capacity and delayed the biodegradability of the biopolymer films in the natural environment. Despite the depletion in water adsorption capacity, all of the product films degraded 50 % within 12 weeks. This study concluded that biopolymers with desirable properties could be formulated by choosing an appropriate casting ratio of the sago starch to NRL with suitable chemical substitution modes.

Melanin is ubiquitous in nature and has wide applications in cosmetics, agriculture, and medicine. The synthesized melanin from bacterium Aeromonas sp. SNS was further used as capping and reducing agents for synthesis of silver nanoparticles (AgNPs). The influence of the experimental parameters (AgNO3, melanin concentrations, and temperature) and their interactions on the nanoparticle synthesis was optimized using response surface methodology (RSM). The Central Composite Design (CCD) with three independent variables was optimized for the effective synthesis of AgNPs. The optimized synthesis of AgNPs was achieved at the shortest time of 14.12 h in the presence of 2.62 mM AgNO3, and 32.30 µg ml−1 melanin concentration at 54.86 °C temperature. The synthesized AgNPs were characterized by means of UV–visible spectroscopy, FTIR, SEM, TEM, and PSD respectively. The AgNPs exhibited excellent antimicrobial activity against human and food-related pathogens. These AgNPs also have strong antioxidant potential which was estimated by DPPH, DMPD and FRAP radical scavenging assays. The 92.62% photocatalytic degradation of 250 PPM brilliant green was observed in 120 min. The present finding accelerates the melanin associated AgNPs could be used in the cosmetic and pharmaceutical industries as well as in textile industries as they have superior antimicrobial, antioxidant, and photocatalytic activity.

Producing nanofibers of a desired predetermined diameter is important for all applications where the nano-sized dimension plays a key role. In this research, nanofibers from a blend of lignin and recycled poly(ethylene terephthalate) (PET) were prepared using the electrospinning process. The design of experiments (DoE) statistical methodology was employed to screen the significant factors and optimize the whole process. A fractional factorial design with five electrospinning variables (spinning distance, solution concentration, voltage, lignin ratio and flow rate) was implemented to identify their effect on the average fiber diameter and on its standard deviation. The morphology of the electrospun mats was examined using Scanning Electron Microscopy. The statistical analysis of the measurements revealed that only the spinning distance and the concentration of the spinning solution have significant effect on the two responses. To minimize the average fiber diameter, the method of steepest descent was applied in two distinct experimental areas. After lowering the solution concentration and the spinning distance up to the point of bead formation, the average fiber diameter was minimized to 191 ± 60 nm. Following the method reported here, tailor-made lignin/recycled PET nanofibers of a set, desired diameter can be fabricated by properly adjusting the electrospinning variables.

Microporous carbon adsorbents with high surface area and porosity were synthesized from lignin using an acrylic acid pretreatment strategy. Lignin was grafted with acrylic acid via hydrothermal treatment to introduce carboxyl groups, as verified by NMR and FT-IR spectroscopy. The incorporated carboxyls enabled ion exchange reactions between lignin and potassium during subsequent potassium hydroxide (KOH) activation. This optimized the dispersion of potassium, allowing effective activation even at low KOH levels. The effects of process parameters, including acrylic acid content, hydrothermal time, and KOH ratio, were investigated. Optimal conditions of 5 wt% acrylic acid and 6 h hydrothermal reaction produced a carbon adsorbent with exceptional Brunauer–Emmett–Teller (BET) surface area of 1708 m2/g and pore volume of 0.82 cm3/g at a lignin:KOH:acrylic acid ratio of 1:0.5:0.05. Characterization by FE-SEM, XRD, EDS, and Raman spectroscopy confirmed the successful synthesis of an optimized microporous carbon material. The carbon exhibited an outstanding lead ion adsorption capacity of 371 mg/g by Langmuir modeling. Adsorption kinetics followed pseudo-second-order, indicating chemisorption as the rate-controlling step. Thermodynamic analysis revealed the endothermic nature of lead adsorption, further enhanced at higher temperatures. Overall, the acrylic acid pretreatment approach enabled sustainable production of high surface area microporous carbon adsorbents from lignin using minimal KOH activation. The adsorbents demonstrated tremendous potential for removing lead ions via chemisorption mechanisms.

Biodegradability and biocompatibility of poly(ε-caprolactone) (PCL) are the prime properties which advanced the use of this polymer in fields of tissue engineering and biomedicals. Being an aliphatic polyester, PCL is prone to undergo trans-esterification which is one of the mechanisms reported for its degradation besides being used in making its copolymers. Trans-esterification occurs both, inter- and intra-molecularly and in this work we report that the mechanism of trans-esterification depends on the molecular weight of the polymer when it is subjected to 160 °C for time up to 24 h. For low molecular weight PCL (Mp = 10,000 g/mol) inter-molecular trans-esterification is the predominant mechanism while for the high molecular weight PCL (Mp = 80,000 g/mol) it is intra-molecular. A mid molecular weight PCL (Mp = 43,000 g/mol) showed presence of both, inter- as well as intra-molecular trans-esterification, when heated at 160 °C for 24 h. A decrease in relative crystallinity for all the samples showed reduction in crystalline component of the polymer confirming occurrence of trans-esterification at chosen conditions. An increase in tensile strength and modulus is observed after treatment at 160 °C for 24 h due to formation of more entangled network of polymer chains as a result of trans-esterification reactions.