Leo Hendrick Baekeland The Bakelizer A Little Bit on Polymers and More on Radical Polymerizations Justin Barry Group Meeting 10/7/2015
Overview of Presentation Global demand Polymerization Basic nomenclature Radical polymerization How radicals react Selectivity and advantages Reversible deactivation polymerization Some considerations on microviscosity Bakelite Rak, M. J.; Friščić, T.; Moores, A. Faraday Discuss 2014, 170, 155 167. Lignin
Ma, J.; Feng, C.; Wang, S.; Zhao, K.-Q.; Sun, W.-H.; Redshaw, C.; Solan, G. A. Inorg Chem Front 2014, 1 (1), 14 4. A Global Demand in Polymers Worldwide commodity 280 million tonnes Two types of polymers Step Chain Polyurethane (PUR) ~7% Polystyrene (PS) ~5% other ~15% Polyvinyl Chloride (PVC) ~16% Low Density Polyethylenes (LLDPE/LDPE) ~18% Polypropylene (PP) ~2% High Density Polyethylene (HDPE) ~16%
Ma, J.; Feng, C.; Wang, S.; Zhao, K.-Q.; Sun, W.-H.; Redshaw, C.; Solan, G. A. Inorg Chem Front 2014, 1 (1), 14 4. A Global Demand in Polymers Worldwide commodity 280 million tonnes Two types of polymers Step Chain Polyurethane (PUR) ~7% Polystyrene (PS) ~5% other ~15% Polyvinyl Chloride (PVC) ~16% Low Density Polyethylenes (LLDPE/LDPE) ~18% Polypropylene (PP) ~2% High Density Polyethylene (HDPE) ~16%
Ma, J.; Feng, C.; Wang, S.; Zhao, K.-Q.; Sun, W.-H.; Redshaw, C.; Solan, G. A. Inorg Chem Front 2014, 1 (1), 14 4. A Global Demand in Polymers Worldwide commodity 280 million tonnes Two types of polymers Step Chain Polyurethane (PUR) ~7% Polystyrene (PS) ~5% other ~15% Polyvinyl Chloride (PVC) ~16% Low Density Polyethylenes (LLDPE/LDPE) ~18% Polypropylene (PP) ~2% High Density Polyethylene (HDPE) ~16%
Carothers, W. H. Chem. Rev. 191, 8 (), 5 426. A Basic Nomenclature of Polymers Polymer structure Condensation polymers Addition polymers Wallace Carothers
Flory, P. J. Chem. Rev. 1946, 9 (1), 17 197. A Basic Nomenclature of Polymers II Polymerization mechanism Step polymers Chain polymers Paul Flory
Preference for Mechanistic Nomenclature Although many condensation polymers are addition polymers, nomenclature isn t interchangeable
The Many Faces of Chain Growth Radical polymerizations Cationic polymerizations Anionic polymerizations
Molecular Weight Why are Radical Polymerizations Widespread? Step 1) Stepwise intermolecular 2) Monomers react with chain or monomers ) All functional groups have same reactivity (monomer, polymer, oligomer) 4) High conversion needed to produce high MW polymers Radical Chain 1) Kinetic chain reaction 2) Initiated by external source ) Monomers react only with active center 4) Polymers grow rapidly and obtain high MW Step Chain % conversion *anionic and cationic highly reactive towards moisture and oxygen 5) Equilibrium controlled See next slide
Odian, G. Principles of Polymerization, 4th Edition; Wiley-Interscience: New York, 2004. Kinetic Steps in Radical Polymerization Initiation Propagation Also chain transfer Termination
Stepto, R. F. T. Pure Appl. Chem. 2009, 81 (2). Weight Fraction Consequences of Radical Chain Reactions Radicals can be selective in their reactivity Molecular weight control Large distributions typical Dispersity (formally PDI) High dispersity due to kinetics Propagation (k p ) is faster than initiation (k I ) M N M V M W Molecular Weight PDI = M W M N
Nucleophilic vs Electrophilic Radicals Radicals have feelings too Donating groups produce nucleophilic SOMO s that interact with LUMO s of electron deficient olefins Withdrawing groups produce electrophilic SOMO s that interact with HOMO s of electron rich olefins σ-p π interaction Inductive interaction
Advanced Free Radical Reactions for Organic Synthesis; Elsevier Science, 2004. E-withdrawing Electron Withdrawing Groups on The Alkenes Relative Reactivity LUMO 1 SOMO E-donating raises energy of SOMO HOMO 84 000 8500
Advanced Free Radical Reactions for Organic Synthesis; Elsevier Science, 2004. E-donating Electron Donating Groups on The Alkenes LUMO Relative Reactivity 1.0 SOMO HOMO.5 E-withdrawing lowers energy of SOMO 2.0
Advanced Free Radical Reactions for Organic Synthesis; Elsevier Science, 2004. *adapted from hand out from Prof. Bruce Branchaud Consequences: Alternating Copolymerization
Advanced Free Radical Reactions for Organic Synthesis; Elsevier Science, 2004. *adapted from hand out from Prof. Bruce Branchaud Radical-Alkene Reaction Step is Selective Favored Disfavored Favored Disfavored
Molecular Orbital Analysis of Reactivity LUMO LUMO LUMO LUMO SOMO SOMO E-donating raises energy of SOMO HOMO HOMO E-withdrawing lowers energy of SOMO Advanced Free Radical Reactions for Organic Synthesis; Elsevier Science, 2004. *adapted from hand out from Prof. Bruce Branchaud HOMO HOMO
Jenkins, A. D.; Jones, R. G.; Moad, G. Pure Appl. Chem. 2009, 82 (2). Bettering the Dispersity Index Living free radical polymerization No termination reactions and only rarely dormant states Reversible deactivation polymerization Predominance of dormant states Stable free radical mediated polymerization (SFRP) Atom-transfer radical polymerization (ATRP) Reversible addition-fragmentation chain transfer polymerization (RAFT)
Nitroxide Mediated SFRP Control of chain growth by reversible termination Stable Free Radical Mediated Radical Polymerization
Atom Transfer Radical Polymerization Control of chain growth through reversible termination
Reversible Addition-Fragmentation Chain Transfer Control of chain growth through reversible chain transfer
England, R. M.; Rimmer, S. Polym. Chem. 2010, 1 (10), 15. Propagation Summary in RAFT Comb polymers by RAFT
Consequences of Living Radical Polymerization Dispersity index Typically <1.2 Slower kinetically Ease of moderating heat in bulk reactions Block copolymers and other architectures are able to be made Dendrimer s by ATRP
Schulz, V. G. V.; Harborth, G. Makromol. Chem. 1947, 1 (1), 106 19. As An Aside, How This Relates to Microviscosity Trommsdorff Effect Limited mobility of propagating chains decreases termination Small monomers are unaffected and still reach the radicals Polymerization of MMA in benzene (Curves represent different concentrations of monomer.)
As An Aside, How This Relates to Microviscosity Initiator efficiency f = 0.-0.8