Effect of starch type on miscibility in poly(ethylene oxide) (PEO)/starch blends and cytotoxicity assays

A Stretchable Polymer Conductor Through the Mutual Plasticization Effect

Intrinsically stretchable conductors play key roles in the dynamic interfacing of electronic devices with soft human tissues. However, it is difficult to simultaneously achieve high electrical conductivity and mechanical stretchability. Here, highly stretchable and conductive thin film electrodes are prepared by combining PEDOT:PSS and a mutually plasticized polymer dopant. Notably, harsh acid treatment for conductivity enhancement is avoided, and good solvent tolerance and high optical transparency are realized, all of which are essential to device fabrication. A transparent electrochromic display is further developed that can bear stretching up to 80% strain, demonstrating its promising application in next-generation optoelectronics.

PBS-Based Green Copolymer as an Efficient Compatibilizer in Thermoplastic Inedible Wheat Flour/Poly(butylene succinate) Blends

Considering the current context of research aiming at proposing new bioplastics with low costs and properties similar to fossil-based commodities currently on the market, in the present work, a hybrid blend containing a prevalent amount of cheap inedible cereal flour (70 wt %) and poly(butylene succinate) (PBS) (30 wt %) has been prepared by a simple, eco-friendly, and low-cost processing methodology. In order to improve the interfacial tension and enhance the adhesion between the different phases at the solid state, with consequent improvement in microstructure uniformity and in material mechanical and adhesive performance, the PBS fraction in the blend was replaced with variable amounts (0–25 wt %) of PBS-based green copolymer, which exerted the function of a compatibilizer. The copolymer is characterized by an ad hoc chemical structure, containing six-carbon aliphatic rings, also present in the flour starch structure. The two synthetic polyesters obtained through two-stage melt polycondensation have been deeply characterized from the molecular, thermal, and mechanical points of view. Copolymerization deeply impacts the polymer final properties, the crystallizing ability, and stiffness of the PBS homopolymer being reduced. Also, the prepared ternary blends were deeply investigated in terms of microstructure, thermal, and mechanical properties. Lastly, both pure blend components and ternary blends were subjected to disintegration experiments under composting conditions. The results obtained proved how effective was the compatibilizer action of the copolymer, as evidenced by the investigation conducted on morphology and mechanical properties. Specifically, the mixtures with 15 and 20 wt % Co appeared to be characterized by the best mechanical performance, showing a progressive increase of deformation while preserving good values of elastic modulus and stress. The disintegration rate in compost was found to be higher for the lower amount of copolymer in the ternary blend. However, after 90 days of incubation, the blend richest in copolymer content lost 62% of weight.

Cationic starches in paper-based applications-A review on analytical methods

This review focuses on cationic starches with a low degree of substitution (<0.06) which are mainly used for production of paper-based products. After a brief introduction on starch in general, cationization pathways and importance of cationic starches in paper production, this review emphasizes on the analytical challenges from different perspectives. These include the different length scales of starches when in solution: the macromolecular level, their assembly into nm aggregates and finally hydrocolloids with hundreds of nanometers of diameter. We give an overview on the current state of the art on the analysis of such challenging samples and aim at providing a guideline for obtaining and presenting reliable analytical data.

Preparation and Composition Optimization of PEO:MC Polymer Blend Films to Enhance Electrical Conductivity

The polymer blend technique was used to improve amorphous phases of a semicrystalline polymer. A series of solid polymer blend films based on polyethylene oxide (PEO) and methylcellulose (MC) were prepared using the solution cast technique. X-ray diffraction (XRD), Polarized optical microscope (POM), Fourier transform infrared (FTIR) and electrical impedance spectroscopy (EIS) were used to characterize the prepared blend films. The XRD and POM studies indicated that all polymer blend films are semicrystalline in nature, and the lowest degree of crystallinity was obtained for PEO:MC polymer blend film with a weight ratio of 60:40. The FTIR spectroscopy was used to identify the chemical structure of samples and examine the interactions between chains of the two polymers. The interaction between PEO and MC is evidenced from the shift of infrared absorption bands. The DC conductivity of the films at different temperatures revealed that the highest conductivity 6.55 × 10^-9 S/cm at ambient temperature was achieved for the blend sample with the lowest degree of crystallinity and reach to 26.67 × 10^-6 S/cm at 373 K. The conductivity relaxation process and the charge transport through the hopping mechanism have been explained by electric modulus analysis. The imaginary part of electrical modulus M″ shows an asymmetrical peak, suggesting a temperature-dependent non-Debye relaxation for the PEO:MC polymer blend system.

Effects of acid hydrolysis intensity on the properties of starch/xanthan mixtures

The effects of acid hydrolysis intensity on the physicochemical properties of starch/xanthan gum (XG) system were studied. Waxy corn starch (WCS) was subjected to different concentrations of hydrochloric acid, and crystallization and relative molecular weight analysis were performed. The results revealed that the starch granules became smaller during acid hydrolysis. X-ray diffraction pattern analysis showed that the crystal structure did not change with acid hydrolysis. Evaluation of the properties and digestibility of different acid-thinned starch/XG systems indicated that the viscosity of acid-thinned starch/XG decreased with increased acid hydrolysis intensity. Rheological property measurements indicated that the compound systems were a pseudo-plastic fluid, which is a typical weak gel structure. Finally, we show that the WCS1.0M/XG has the highest stability of the tested mixtures. We conclude that adjusting the conditions of acid hydrolysis improves the stability and food quality-enhancing properties of starch.

Crystallization behaviour of poly(ethylene oxide) under confinement in the electrospun nanofibers of polystyrene/poly(ethylene oxide) blends

We have studied the confined crystallization behaviour of poly(ethylene oxide) (PEO) in the electrospun nanofibers of the phase-separated blends of polystyrene (PS) and PEO, where PS was present as the major component. The size and shape of PEO domains in the nanofibers were considerably different from those in the cast films, presumably because of the nano-dimensions of the nanofibers and the extensional forces experienced by the polymer solution during electrospinning. The phase-separated morphology in turn influenced the crystallization behaviour of PEO in the blend nanofibers. At a PEO weight fraction of ≥0.3, crystallization occurred through a heterogeneous nucleation mechanism similar to that in cast blend films. However, as the PEO weight fraction in the blend nanofibers was reduced from 0.3 to 0.2, an abrupt transformation of the nucleation mechanism from the heterogeneous to predominantly homogenous type was observed. The change in the nucleation mechanism implied a drastic reduction of the spatial continuity of PEO domains in the nanofibers, which was not encountered in the cast film. The melting temperature and crystallinity of the PEO crystallites developed in the nanofibers were also significantly lower than those in the corresponding cast films. The phenomena observed were reconciled by the morphological observation, which revealed that the phase separation under the radial constraint of the nanofibers led to the formation of small-sized fibrillar PEO domains with limited spatial connectivity. The thermal treatment of the PS/PEO blend nanofibers above the glass transition temperature of PS induced an even stronger confinement effect on PEO crystallization.

Anticancer activity of starch/poly[N-(2-hydroxypropyl)methacrylamide]: biomaterial film to treat skin cancer

In the present work, films of pHPMA, pHPMAS hybrid, pHPMA-CPT and pHPMAS-CPT hybrid were prepared by solvent casting method and characterized by FT-IR, FT-Raman, XRD and DSC, respectively. The biocompatibility of the prepared pHPMA film and pHPMAS hybrid film were assessed using VERO cell lines and the percentage cell viability was found to be 97.4 and 98.3% for 7.8 μg/ml of the film extracts after 72 h of incubation. The cancer cell viability of the pHPMA-CPT film and pHPMAS-CPT film using MCF7 cell lines at pH 5.5 and 7.4 were found to be 4.9 and 8.6% and 7.7 and 12.3%, respectively. In vitro release of camptothecin from pHPMA-CPT and pHPMAS-CPT films in phosphate-buffered saline solution at pH 5.5 and 7.4 were monitored and analyzed using UV-vis spectrophotometer at λmax of 360 nm.

Polyox and carrageenan based composite film dressing containing anti-microbial and anti-inflammatory drugs for effective wound healing

Polyethylene oxide (Polyox) and carrageenan based solvent cast films have been formulated as dressings for drug delivery to wounds. Films plasticised with glycerol were loaded with streptomycin (30%, w/w) and diclofenac (10%, w/w) for enhanced healing effects in chronic wounds. Blank and drug loaded films were characterised by texture analysis (for mechanical and mucoadhesive properties), scanning electron microscopy, differential scanning calorimetry, X-ray diffraction and Fourier transform infrared spectroscopy. In addition, swelling, in vitro drug release and antibacterial studies were conducted to further characterise the films. Both blank and drug loaded films showed a smooth, homogeneous surface morphology, excellent transparency, high elasticity and acceptable tensile (mechanical) properties. The drug loaded films showed a high capacity to absorb simulated wound fluid and significant mucoadhesion force which is expected to allow effective adherence to and protection of the wound. The films showed controlled release of both streptomycin and diclofenac for 72 h. These drug loaded films produced higher zones of inhibition against Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli compared to the individual drugs zones of inhibition. Incorporation of streptomycin can prevent and treat chronic wound infections whereas diclofenac can target the inflammatory phase of wound healing to relieve pain and swelling.

Preparation, optimisation and characterisation of novel wound healing film dressings loaded with streptomycin and diclofenac

Streptomycin (STP) and diclofenac (DLF) loaded film dressings were prepared by blending Polyox(®) (POL) with four hydrophilic polymers [hydroxypropylmethylcellulose (HPMC), carrageenan (CAR), sodium alginate (SA) or chitosan (CS)] using glycerol (GLY) as plasticiser. The films were characterised by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy, texture analysis (tensile and swelling characteristics) and in vitro dissolution profiles using Franz diffusion cell. SEM showed homogeneous morphology for both blank (BLK) and drug loaded (DL) films. Films prepared by blending of POL with the other polymers showed a reduction in the crystallisation of POL in descending order of SA>CS>HPMC>CAR respectively. DSC and XRD showed no crystalline peaks of STP and DLF suggesting molecular dispersion of both drugs as well as possible drug interaction with negatively charged sulphate ions present in CAR. The DL films did not show any IR bands of both drugs, confirming the DSC and XRD results. POL-CAR-BLK films showed higher tensile strength (12.32±1.40 MPa) than the POL-CAR-DL films (9.52±1.12 MPa). DL films plasticised with 25%w/w GLY revealed soft and tough (tensile strength 1.02±0.28 MPa, % elongation 1031.33±16.23) formulations. The swelling capacities of POL-CAR-BLK and POL-CAR-DL films were (733.17±25.78%) and (646.39±40.39%), increasing to (1072.71±80.30%) and (1051±86.68%) for POL-CAR-BLK-25% GLY and POL-CAR-DL-25% GLY respectively. POL-CAR-DL films showed significantly (n=3, p<0.0318) lower cumulative release of STP and DLF (52.11±1.34, 55.26±2.25) compared to POL-CAR-DL-25% GLY films (60.07±1.56, 63.39±1.92) respectively.