Enzymatic grafting: A novel approach to develop multifunctional materials of interest

Today more than 99% of plastics are petroleum-based because of the availability and cost of the raw material. The durability of disposed plastics contributes to the environmental problems as waste and their persistence in the environment causes deleterious effects on the ecosystem. Environmental pollution awareness and the demand for green technology have drawn considerable attention of both academia and industry into biodegradable polymers. In this regard green chemistry technology has the potential to provide solution to this issue. Enzymatic grafting has recently been the focus of green chemistry technologies due to the growing environmental concerns, legal restrictions, and increasing availability of scientific knowledge. Over the last several years, research covering various applications of robust enzymes like laccases and lipases has been increased rapidly, particularly in the field of polymer science, to graft multi-functional materials of interest. In principle, enzyme-assisted grafting may modify/impart a variety of functionalities to the grafted composites which individual materials fail to demonstrate on their own. The modified polymers through grafting have a bright future and their development is practically boundless. In the present study series of graft composites with poly(3-hydroxybutyrate) (P(3HB) as side chain and cellulose as a backbone polymer were successfully synthesised by introducing enzymatic grafting technique where laccase and lipase were used as model catalysts [1-3]. Subsequently, the resulting composites were removed from the casting surface under ambient environment and characterised by Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and X-ray diffraction (XRD) in detail. Moreover, the thermo-mechanical behaviours of the grafted composites were investigated by differential scanning calorimetry (DSC) and dynamic mechanical analyser (DMA) measurements, respectively. In addition, hydrophobic and hydrophilic characteristics of the grafted polymers were studied through drop contour analysis using water contact angle (WCA). In comparison to the individual counterparts improvement was observed in the thermo- mechanical properties of the composites to varied extent. The tensile strength, elongation at break, and Young’s modulus values of the composites reached their highest levels in comparison to the films prepared with pure P(3HB) only which was too fragile to measure any of the above said characteristics. Interestingly, untreated P(3HB) was hydrophobic in nature and after lipase treatment P(3HB) and P(3HB)-EC-based graft composite attained higher level of hydrophilicity. This is a desired characteristic that enhances the biocompatibility of the materials for proper cell adhesion and proliferation therefore suggesting potential candidates for tissue engineering/bio-medical type applications [3]. The present research will be a first step in the biopolymer modification. To date no report has been found in literature explaining the laccase/lipase assisted grafting of P(3HB) [1-3]. The newly grafted composites exhibit unique functionalities with wider range of potential applications in bio-plastics, pharmaceutical, and cosmetics industries, tissue engineering, and biosensors. [1] H.M.N. Iqbal, G. Kyazze, T. Tron and T. Keshavarz, Cellulose 21, 3613-3621 (2014). [2] H.M.N. Iqbal, G. Kyazze, T. Tron and T. Keshavarz, Carbohydrate Polymers 113, 131-137 (2014). [3] H.M.N. Iqbal, G. Kyazze, T. Tron and T. Keshavarz, Polymer Chemistry In-Press, DOI: 10.1039/C4PY0 0857J (2014).

Be careful what you wish for: the legal parameters of EU withdrawal

Easiness with which the political circles talk about withdrawal from the European Union is rather surprising and proves that the legal parameters of an EU exit are not treated seriously enough. In theoretical terms Article 50 TEU allows for a unilateral exit as well as for a consensual divorce. Arguably, the first is an interesting abstract proposition, which, however, in practical terms seems to be an unworkable solution. Hence, the only realistic option is a proper divorce based on a withdrawal agreement. As per Article 50 TEU, it would be negotiated by the European Union with a departing country and should cover the terms of withdrawal and “take account of future relations” between the EU and the divorcee. It is submitted that in order to avoid a legal vacuum, this agreement should not only “take account of future relations” but actually deal with them thoroughly. This will make the negotiations difficult and, most likely, time consuming. One also has to envisage a scenario whereby a country leaving the European Union would join EFTA and become a EFTA-EU Member State of the European Economic Area. Should that happen the scope of a EU withdrawal agreement would be limited to the terms of exit, while future relations between the divorcee and the European Union would be mainly covered by the EEA Agreement. This chapter unlocks the mechanics of Article 50 TEU and the withdrawal procedure it provides for. It covers the issues that should be attended to by the negotiators and provides an overview of dossiers that are likely be covered in a withdrawal agreement.