RT info:eu-repo/semantics/doctoralThesis
T1 High porosity polymers for advanced applications
A1 Esteban Hernández, Isabel Noelia
A2 Universidad de Valladolid. Escuela de Doctorado
K1 Catálisis
K1 Porous polymers
K1 Polímeros porosos
K1 Heterogeneous catalysis
K1 Catálisis heterogénea
K1 Gas separation
K1 Separación de gases
K1 Palladium
K1 Paladio
K1 23 Química
AB In this thesis, polymeric systems possessing functional groups capable of coordinating with transition metals have been designed and prepared for use as confined catalytic materials. For this purpose, microporous polymeric networks have been prepared using bidentate electrophilic monomers such as bipyridine groups contained in 4,5-diazafluoren-9-one (DF) and aromatic diphosphines such as 1,2-bis(diphenylphosphino)ethane (DPPE), 1,3-bis(diphenylphosphino)propane (DPPP) and 1,4-bis(diphenylphosphino)butane (DPPB). The porous polymeric networks presented in this work as catalytic supports have been synthesized by polymerization reactions via electrophilic aromatic substitution (SEAr) promoted in super acidic medium in the case of DF monomer-derived materials and via Friedel-Crafts in the case of aromatic diphosphines. The optimization of the SEAr reactions to prepare microporous polymeric networks (POPs) was carried out, in a first stage, by determining the differential reactivity of the DF monomer versus that of other electrophilic monomers, isatin (IS) and methyl-isatin (MeIS), commonly used in this type of reactions. For this purpose, linear homopolymers and copolymers were obtained by combining the diffunctional nucleophilic monomer biphenyl (BP) with one or two of the electrophilic monomers (DF/IS and DF/MeIS). To optimize the polymerization reaction, different conditions were used varying parameters such as temperature, time and use, or not, of cosolvents. Although a lower reactivity of DF compared to IS and MeIS was observed, optimal conditions were achieved to prepare high molecular weight polymers.  In a second step, the optimization results were tuned for the synthesis of POPs using trifunctional nucleophilic monomers such as 1,3,5-triphenylbenzene (135TPB) or triptycene (TRP). These polymeric materials showed excellent chemical and thermal stability (thermal degradations above 500 °C), and good mechanical properties which allowed their use as gas separation materials. It was observed that DF-derived polymers containing bipyridine groups could be protonated and that these protonated membranes possessed excellent CO2 separation ability. Furthermore, IS- and MeIS-derived POPs were employed as fillers to prepare mixed matrix membranes (MMMs), which exhibited excellent gas separation properties.The POPs obtained using 135TPB and DF (or mixtures of DF and IS) were amorphous and highly microporous (surface areas between 760 and 935 m2/g).On the other hand, taking into account the metal coordination capacity of the phosphorus atom of aromatic phosphines, and the versatility of a synthetic methodology that allows the fabrication of porous hypercrosslinked polymers (HCPs), three new families of HCPs were obtained by reacting an aromatic diphosphine (DPPE, DPPP or DPPB) with 135TPB, or a mixture of 135TPB and BP, using dimethoxymethane (DMM) as crosslinking agent, iron chloride as Lewis acid and 1,2-dichloroethane as solvent. These materials had moderate thermal stabilities due to the degradation of their methylene bridges and high surface areas between 760 and 1300 m2/g, showing a high contribution of microporosity in some polymeric networks. The two families of POPs and HCPs were used as precursors to prepare confined heterogeneous catalysts by their coordination with palladium(II) acetate. These catalysts were evaluated in Suzuki-Miyaura cross-coupling reactions using green solvents and aerobic conditions, and it was observed that the materials exhibited excellent conversions and high TON and TOF. Moreover, these confined heterogeneous catalysts could be recycled for at least five cycles without loss of catalytic activity or leaching.
YR 2024
FD 2024
LK https://uvadoc.uva.es/handle/10324/71619
UL https://uvadoc.uva.es/handle/10324/71619
LA eng
NO Escuela de Doctorado
DS UVaDOC
RD 23-nov-2024