Nowadays, plastic contamination worldwide is a concerning reality that can be addressed with appropriate society education as well as looking for innovative polymeric alternatives based on the reuse of waste and recycling with a circular economy point of view, thus taking into consideration that a future world without plastic is quite impossible to conceive. In this regard, in this review, we focus on sustainable polymeric materials, biodegradable and bio-based polymers, additives, and micro/nanoparticles to be used to obtain new environmentally friendly polymeric-based materials. Although biodegradable polymers possess poorer overall properties than traditional ones, they have gained a huge interest in many industrial sectors due to their inherent biodegradability in natural environments. Therefore, several strategies have been proposed to improve their properties and extend their industrial applications. Blending strategies, as well as the development of composites and nanocomposites, have shown promising perspectives for improving their performances, emphasizing biopolymeric blend formulations and bio-based micro and nanoparticles to produce fully sustainable polymeric-based materials. The Review also summarizes recent developments in polymeric blends, composites, and nanocomposite plasticization, with a particular focus on naturally derived plasticizers and their chemical modifications to increase their compatibility with the polymeric matrices. The current state of the art of the most important bio-based and biodegradable polymers is also reviewed, mainly focusing on their synthesis and processing methods scalable to the industrial sector, such as melt and solution blending approaches like melt-extrusion, injection molding, film forming as well as solution electrospinning, among others, without neglecting their degradation processes.

The objective of this work is to evaluate the reprocessing of PLA 3D printing waste from different origins, into filaments and films, and without the addition of any additive. Two types of waste were considered: a blend of different printing wastes (masks, visors, other components) of personal protective equipment coming from an association of Spanish coronamakers, and PLA waste from a single known commercial source. Both types of materials were subjected to repeated extrusion cycles and processed into films by compression molding. Samples were characterized after each cycle and their mechanical and viscosity properties evaluated. Diffusion-ordered NMR spectroscopy (DOSY) experiments were also carried out to estimate molecular weights. The results show a better performance for the PLA waste from the known origin, capable of withstanding up to three re-extrusion cycles per two for the waste blending, without significant degradation. Additionally, a model to address collection and mechanical recycling cycles under two different scenarios (full traceability and not full traceability) was proposed.

This study examines an example of the alternative conceptions and conceptual errors of students at the higher education level in a scientific context. It begins by introducing the significance and characteristics of preconceptions and alternative ideas or alternative conceptions, highlighting their impact on students’ misconceptions. Using the dissolution of a gas (oxygen) in a liquid (water) as the case study, and based on the answers to a questionnaire, this work analyzes the responses by university students which, in most cases, lack scientific rigor. The questionnaire used in this study has been designed in such a way that students provide three types of answers: the first is a yes/no/do not know question; the second is a short answer question to briefly explain the previous answer; and the third is a drawing answer question in which students are required to interpret the phenomenon at the molecular level by drawing a picture. Surprisingly, minimal differences were observed between the university students enrolled in Bachelor’s degree programs (Chemical Engineering or Industrial Engineering) and Master’s degree programs (Master’s Degree in Teacher Training), over the five years (from 2018/19 to 2022/23) covered by this study. Only about 11% of the students provided acceptable reasoning, while the rest demonstrated alternative conceptions. These alternative conceptions encompassed concepts such as the formation of oxygenated water instead of the dissolution, the belief that gases do not dissolve in liquids, confusion about atomic and molecular levels, difficulties in interpreting scientific language, and reliance on simplistic and naïve ideas, among others. After the teacher’s review, the questionnaire and students’ answers were discussed in class in order to detect and correct errors. Approximately one month later, the students were asked to repeat the same questionnaire, when it was observed that the number of correct answers, showing adequate reasoning, had increased to 75%. The results of this study, using a very simple questionnaire that only takes 10 min, could be valuable for guiding teachers to question and transform their pedagogical content knowledge in order to improve the transmission of scientific content, which may involve difficulties that, a priori, were not expected in university students.

The synthesis of 5-chloro-8-nitro-1-naphthoyl chloride and its use as a protective group for amines is described. Protection is carried out with an auxiliary amine or under mild Schotten-Baumann conditions in high yield (>86%), while deprotection can be achieved easily under gentle reducing conditions due to the large steric tension between C-1 and C-8 naphthalene substituents. The reaction has been successfully tested in dipeptide synthesis and amino alcohols protection, and it has proved selective for the ε-amine group of lysine.