From micro to nano: polypropylene composites reinforced with TEMPO-oxidised cellulose of different fibre widths

TEMPO-oxidised cellulose fibres are often explored as nano-reinforcement for polymers. However, it is unclear whether micrometre-sized TEMPO-oxidised cellulose fibres also possess similar reinforcing potential. In this work, we report the mechanical response of polypropylene (PP) composites reinforced with TEMPO-oxidised cellulose (TOC) of different fibre widths. Micrometre-sized TOC fibres (TOCF) containing sodium carboxylate (TOCF-Na) and free hydroxyl (TOCF-H) groups, as well as nano-sized TOC nanofibrils (TOCN) were produced from dissolving pulp and incorporated into PP matrix via melt-extrusion. It was found that model PP composites containing micrometre-sized TOCF-Na and TOCF-H possessed the highest tensile modulus of up to 2.5 GPa; 40% improvement over neat PP and 30% increase over PP/TOCN composite. No significant differences in the tensile strength of PP/TOCF-Na and PP/TOCF-H composites were observed when compared to neat PP. The incorporation of nano-sized TOCN into PP however, led to a 6% decrease in tensile strength. Single-edge notched beam fracture toughness test further showed that PP/TOCN composite possessed the lowest fracture toughness of 2.52 MPa m1/2; a decrease of 18% over PP reinforced with micrometre-sized TOCF-Na and TOCF-H. Our study shows that micrometre-sized TOCFs serve as better reinforcement for polymers compared to nano-sized TOCN. This is attributed to the better dispersion of TOCF in the PP matrix. Furthermore, the presence of surface microfibrillation on TOCFs also enhanced the quality of the TOCF-PP interface through mechanical interlocking and local stiffening of the PP matrix.

Preparation and Structures of Rare Earth 3-Benzoylpropanoates and 3-Phenylpropanoates

Rare earth (RE) complexes of 3-benzoylpropanoate (bp), [RE(bp)3(H2O)n] (RE=La, n=2; RE=Y, Ce, Pr, Nd, Yb, n=1) and 3-phenylpropanoate (pp), [RE(pp)3] (RE=Y, La, Ce, Nd, Yb), have been prepared by metathesis reactions between the corresponding rare earth chloride and the appropriate sodium carboxylate. Analysis by single-crystal X-ray diffraction finds that both RE bp and pp complexes favour formation of carboxylate-bridged 1-D coordination polymers in the solid state. Here, the former favours heteroleptic 9 or 10-coordinate complexes (splitting between Ce and La) with the carbonyl remaining uncoordinated but participating as a hydrogen bond acceptor with water in the coordination sphere. Lack of bp carbonyl coordination leaves this group available for surface interactions during corrosion inhibition and complex solubilization. The latter pp derivatives form eight-coordinate complexes for Y and Yb and are the first examples of homoleptic RE pp complexes to be reported.

Fabrication of Water Absorbing Nanofiber Meshes toward an Efficient Removal of Excess Water from Kidney Failure Patients

Excellent water-absorbing nanofiber meshes were developed as a potential material for removing excess fluids from the blood of chronic renal failure patients toward a wearable blood purification system without requiring specialized equipment. The nanofiber meshes were successfully fabricated from poly(acrylic acid) (PAA) under various applied voltages by appropriately setting the electrospinning conditions. The electrospun PAA nanofibers were thermally crosslinked via heat treatment and then neutralized from their carboxylic acid form (PAA) to a sodium carboxylate form poly(sodium acrylate) (PSA). The PSA nanofiber meshes exhibited a specific surface area 393 times that of the PSA film. The PSA fiber meshes showed a much faster and higher swelling than its corresponding film, owing to the higher capillary forces from the fibers in addition to the water absorption of the PSA gel itself. The proposed PSA fibers have the potential to be utilized in a new approach to remove excess water from the bloodstream without requiring specialized equipment.

Ecofriendly synthesis and characterization of carboxylated GAP copolymers

Carboxylated GAP copolymers (polyGA-carboxylate) compounds (1–7), were synthesized by the simultaneous substitution reaction with PECH, sodium azide, and sodium carboxylate in DMSO.

Sodium–carboxylate contact ion pair formation induces stabilization of palmitic acid monolayers at high pH

Theory and experiments show that ion-pair formation drives adsorption of deprotonated fatty acids to the interface.