From batch to continuous free-radical polymerization: Recent advances and hurdles along the industrial transfer

The care of safety and environment is nowadays an essential aspect in the conduction of every kind of factory. A decisive contribution to these aspects is given by the conversion from batch to continuous processes. In polymer manufacturing, this transition allows to better manage important safety and pollution concerns, such as energy transport phenomena and process emissions. This, in turn, facilitates the fulfilling of the more and more stringent requirements imposed by local and international regulatory agencies. In addition, through this process intensification, it is also possible to optimize both investment and operative costs, thus overcoming the current profit margin reduction in the field of polymerizations. The aim of this chapter is to provide an insight into the technical and process difficulties that are currently hampering the transition from batch to continuous free-radical polymerization (FRP). The discussion is driven by considering key points in polymer manufacturing, including safety, environmental concerns, product quality and cost management. For a seek of clarity, we drove the discussion by considering the two main modalities in which the FRP can be conducted, namely homogenous and heterogeneous reactions. Extensive reference to literature examples is made to highlight the state of art in the field and the recent innovations toward continuous processes. Finally, successful examples of such auspicable transition achieved on an industrial scale are presented, trying to highlight the features that can be generalized to reach the goal

Surfactant-free and rinsing-resistant biodegradable nanoparticles with high adsorption on natural fibers for the long-lasting release of fragrances

Synthetic polymers are attracting growing attention as additives for laundry and personal care products. In particular, the high volatility of many common fragrances requires the development of polymeric particles for their encapsulation and controlled release. Unfortunately, the vast majority of these carriers is made from polymers that are not biodegradable. This poses severe concerns about the accumulation of nano- and microplastics. Hence, such particles are expected to be banned from the market in the coming years. Therefore, biodegradable particles enabling a long-lasting release of the fragrances are urgently needed. In this work, we produced biodegradable nanoparticles (NPs) that are structurally composed of lactones, i.e. well known perfumes that occur naturally and that are already considered safe by regulatory agencies. We polymerized these lactones via ring opening polymerization (ROP) using an ionizable tertiary amine as initiator to produce in a single step amphiphilic oligoesters able to directly self-assemble into NPs once nanoprecipitated in water. In this way, we can produce biodegradable NPs with a perfume loading up to 85 % w/w without the need for additional surfactants. Subsequently we show that the ionizable group is able to confer a positive charge to our nanoparticles and, in turn, a high adsorption capacity on natural fibers (i.e. hairs and cotton fabric). Finally, we demonstrate the nanoparticle resistance to rinsing and their ability to confer a long-lasting fragrance perception to treated hair swatches for at least 3 weeks

Innovative Magnetic Aggregates for the Removal of Transition Metals from Industrial Wastewater

A novel adsorbent material based on microaggregates of Fe3O4 magnetic nanoparticles functionalized with succinic acid has been developed. The magnetic aggregates (MA) were characterized in terms of the size distribution (master sizer analysis), morphology (TEM), chemical structure (IR-spectroscopy and XRD), magnetic properties (VSM), and Z-Potential. The effects of various parameters such as contact time, dosage of magnetic aggregates, the amount of succinic acid on the magnetic aggregates on the adsorption capacity, as well as the efficiency of the treatment in the adsorption of two transition metals, copper (Cu) and zinc (Zn) from real wastewater, were investigated. The kinetic behavior was analyzed by using the Lagergren pseudo-first-order, pseudo-second-order, and Elovich and intra-particle diffusion models. Langmuir and Freundlich’s models were applied to simulate the adsorption equilibrium. The magnetic aggregates reached the equilibrium condition relatively fast, within 10 min. Magnetic aggregates with a higher amount of succinic acid in their formulation showed a higher adsorption capacity of the two metals in all the experiments. This is consistent with the adsorption mechanism mainly based on electrostatic interaction between the metal ions and the negative charges on the surface of magnetic aggregates. A higher adsorption capacity for the removal of copper compared to zinc was found. Additionally, the electrochemical characterization of the magnetic aggregates was done as a preliminary study for proposing a regeneration method of the MA along with the extraction metals adsorbed based on an electrochemical process

Polymer Nanoparticles for the Release of Fragrances: How the Physicochemical Properties Influence the Adsorption on Textile and the Delivery of Limonene

The market of cosmetic and personal care products is continuously growing its impact. In particular, the products that are currently driving this growth have a strict connection with fragrances (e.g., perfumes, detergents, body creams, and softeners). Since the fragrances are volatile molecules, very often, they are encapsulated in polymeric nanoparticles (NPs) that mediate their release and hence prolong the fragrance perception. Toward this aim, it is highly desirable to maximize the interaction between the carrier and the substrate, which would avoid the NP desorption following scrubbing and repeated washing. In the case of laundry products, limited NP desorption is also crucial to prevent the accumulation of nanoplastics in the environment, which is nowadays strictly regulated. Therefore, a thorough study highlighting the influence of the different physicochemical properties of the NPs on their adsorption behavior is urgently required. In this work, we synthesized polymer NPs with different sizes, surface charges, glass transition temperatures, and degrees of cross-linking through emulsion free-radical polymerization to investigate how these parameters affect the NP adsorption onto a textile substrate (composition: 90% cotton/10% elastane). This study can provide interesting guidelines in the design of new fragrance delivery systems as well as in the optimization of those already adopted in the market. Finally, we investigated the possibility of loading and mediating the release in air of limonene, one of the most common odorous molecules in the cosmetic field, overcoming its well-known volatility