Sumários
Chemical Reactions in Polymers. Natural Polymers. MAP12 Quiz.
21 abril 2022, 09:30 • Pedro Teixeira Gomes
Chemical Reactions in Polymers:
Functional group reactions.
Ring formation reactions (in the polymer backbone).
Crosslinking reactions.
Block and graft copolymer formation.
Polymer degradation.
Natural Polymers:
Polysaccharides of vegetal origin (cases): Cellulose, Amylose and Amylopectin. Polysaccharides of animal origin (cases): Chitin, Chitosan and Glycogen.
Modifications of cellulose (cases): Cellulose xanthate (viscose rayon textile fibres); Cellulose acetate (rayon acetate textile fibres); Cellulose nitrate (plastics, lacquers, explosives); Hydroxyethyl Cellulose (emulsifiers, shampoo thickeners).
Natural Rubber: from Gutta Percha tree (thermoplastic - trans-1,4-isoprene), from Hevea Brasiliensis tree and Guayule bush (elastomer - cis-1,4-isoprene)
Polypetides (Proteins)
Nucleic Acids
MAP12 Quiz
Chain-Growth Polymerization (cont.). Coordination Polymerization.
19 abril 2022, 11:30 • Pedro Teixeira Gomes
- Polymerization of Olefins (insertion): Monomers (olefins, dienes e cycloolefins). Commodity polyolefins (physical and production features of low density polyethylene (LDPE), high density polyethylene (HDPE), linear low density polyethylene (LLDPE) and polypropylene (PP). Ziegler-Natta catalysts: definition. First, second and third generation Ziegler-Natta catalysts. Phillips catalysts. Homogeneous Ziegler-Natta catalysts: metallocenes; MAO (methylaluminoxane) cocatalysts. Role of the MAO cocatalyst. General mechanism of Ziegler-Natta catalysis. Ziegler-Natta stereospecific catalysts and ansa-metallocene catalysts. Isospecific and syndiospecific ansa-metallocenes. General features of metallocenic polyolefins.
- Polymerization of Dienes (insertion): 1,4-cis-polybutadiene (synthetic rubber), 1,4-trans polybutadiene and 1,2-polybutadiene; 1,4-cis-polyisoprene (natural rubber and synthetic natural rubber) and 1,4-trans-polybutadiene. Stereospecific catalysts: 1) Ziegler-Natta e 2) Allyl complexes (without Al cocatalysts). Allyl Ni catalysts: influence of the addition of a phosphine. Stereoregulating mechanism.
- Ring Opening Metathesis Polymerization (ROMP): Reaction of ring-opening metathesis. Type of monomers (cycloolefins and cycloalkynes). Catalysts: 1) Ziegler-Natta catalysts and 2) well-defined catalysts (metal carbenes). ROMP mechanism. Examples of polymers and copolymers obtained from the ROMP polymerization of a single cyclomonomer.
- Ring Opening Polymerization (ROP): Monomers (epoxides, cyclic lactams, cyyclic lactone, cyclic dilactones, N-carboxyanhydrides, cyclic carbonates, cyclic siloxanes). Catalysts (alkyl and alkoxide transition metal and main-group metal complexes). Synthesis of polyethers. Synthesis of polyamides and polyesters. Synthesis of streoregular poly(lactic acid) (PLA). Synthesis of polycarbonates, polypeptides and silicones.
- Modes of initiation of most general monomers (summary): Free radical, Cationic, Anionic and Coordination.
Polymers characterization
18 abril 2022, 10:30 • Rui Galhano dos Santos
Characterization of the synthesized polymers by FTIR-ATR, GPC and DSC.
Chain-Growth Polymerization (cont.). Ionic Polymerization: Anionic and Cationic Polymerization. MAP 11 Quiz.
12 abril 2022, 11:30 • Pedro Teixeira Gomes
Anionic Polymerization:
Characteristics (monomers prone to anionic polymerization). Anionic initiators (by anionic addition, by electron transfer). Mechanism and kinetics. Molecular weight control. Living Polymerization. Polymer chain ends functionalization. Telechelic polymerization. Stereochemistry of anionic polymerization. AB and ABA block copolymers (blend compatibilizers and thermoplastic elastomers (TPEs). Star-block copolymers. Ring opening polymerization of non-vinyl monomers (epoxides, cyclic trimer of formaldehyde, lactams, N-carboxyanhydrides, cyclic siloxanes). Polymeric architectures accessible by living polymerization.
Cationic Polymerization:
Characteristics (monomers that undergo cationic polymerization). Cationic initiators. Mechanism and kinetics (chain transfer and chain termination). Living cationic polymerization. Strereochemistry of cationic polymerization. Ring opening polymerization of non-vinyl monomers (epoxides, cyclic ethers, cyclic trimer of formaldehyde). Cationic copolymerization (Butyl Rubber). Commercially important polymers prepared by ionic polymerization.
MAP11 Quiz.