Sumários

Exercises and Problems. Preparation for the MAP45

13 abril 2023, 14:00 • Pedro Teixeira Gomes

Exercises and Problems :

Exercises about Anionic and Cationic Polymerization, Coordination Polymerization and Reactions in Polymers.

General doubts and preparation for the MAP45.


Chemical Reactions in Polymers. Exercises and Problems

12 abril 2023, 09:00 • 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.


Quiz10


Exercises and Problems :

Exercises about Controlled Radical Polymerization.

Chain-Growth Polymerization (cont.): Coordination Polymerization (cont.)

11 abril 2023, 12:00 • Pedro Teixeira Gomes

Coordination Polymerization (cont.):

- 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.

Chain-Growth Polymerization (cont.): Cationic Polymerization. Coordination Polymerization

30 março 2023, 14:00 • Pedro Teixeira Gomes

Cationic Polymerization:

Characteristics (monomers that undergo cationic polymerization). Cationic initiators.

Mechanism and kinetics (chain transfer and chain termination).

Living cationic polymerization.

Stereochemistry 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.


Coordination Polymerization:

- 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.

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.

Copolymerization of olefins with ansa-metallocene catalysts.


Quiz 9.

Chain-Growth Polymerization (cont.): Controlled Radical Polymerization (CRP/RDRP). Anionic Polymerization.

29 março 2023, 09:00 • Pedro Teixeira Gomes

Controlled Radical Polymerization

Living Polymerization vs. Controlled Radical Polymerization (CRP), i.e. Reversible-Deactivation Radical Polymerization (RDRP).

Main Techniques of CRP/RDRP (NMP, ATRP, RAFT Polymerization):

- Nitroxide-Mediated Polymerization (NMP): Mechanism, Types of initiators/deactivators, Kinetics, End-groups, Molecular weight distribution, dependence of M n with conversion.

- Atom Transfer Radical.Polymerization (ATRP): Mechanism, Types of initiators/deactivators, Types of complexes/ligands, Kinetics, End-groups, Molecular weight distribution, dependence of M n with conversion.

- Reversible Addition-Fragmentation Chain Transfer (RAFT) Polymerization: Mechanism, Types of initiators an chain transfer agents (CTA), Kinetics, End-groups, Molecular weight distribution, dependence of M n with conversion.

Reactivity of Monomrs (ATRP vs. RAFT).Comparison of Radical Polymerization Processes: Free-Radical Polymerzation vs. Ideal Living Polymerization vs. RDRP.Comparison of ATRP vs. RAFT Polymerization.

Polymer Architectures accessible by Living Polymerization.Block copolymers by ATRPand RAFT.

Functionalization of end-groups in by ATRP and RAFT.


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.


Quiz 8.