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Prof. Steve ArmesDept. of Chemistry, U. Sheffield
Polymerisation -Induced Self-Assembly
FRS Talk, 11.7.2014
Polymers are Long-Chain Molecules
= repeat unit
Polymers (plastics) are ubiquitous in the modern wo rld
Polymers are extremely racist
Get microphase separation on 10-50 nm length scale!
3 µmPhase separation constrained by covalent
bond between red and blue chains
What happens if red and blue polymer chains are attached to each other?
AB diblock
copolymer
Instead, macrophase-separated blends are formed on the micron length scale
+Pairs of red + blue polymers do not mix:
How to make block copolymer nanoparticles
O
O
HO
HO
65
+ O
O
HO
HHHHPPPPMMMMAAAAPGMA65 macroCTA
PGMA 65 – PHPMA X
X = 100
X = 300
X = 30
Efficient aqueous formulation: > 99 % conversion wi thin 2 h at 70 oC
water-solublePGMA65
water-miscibleHPMA
(but PHPMA iswater-insoluble)
Y. T. Li and S. P. Armes, Angewandte Chem., 2010, 49, 4042
Grow a water-insoluble polymer from one end of a water-soluble polymer in water
A. Blanazs et al., JACS, 2011, 133, 16581 Scale bars: 200 nm
75 min = 62 %, DP 123
77.5 min = 68 %, DP 131
84 mins = 75 %, DP 150
225 mins = 100 % DP 200
90 mins = 82 %, DP 164
65 min = 46 %, DP 92
87 mins = 78 % DP 156
1H NMR & TEM Studies: PGMA47-PHPMA200
Predictive Phase Diagrams
Increasing PHPMA DP and copolymer concentration
Spheres Worms Vesicles
Post- mortem TEM analysis of diblock copolymer morphology at > 99 % conversion
A. Blanazs, A. J. Ryan, S. P. Armes, Macromolecules 2012, 45, 5099
PGMA78-PHPMAx
S = spheres, W = worms, V = vesicles
78 x
Phase diagrams serve as a ‘road map’
Enable reproducible synthesis of pure
copolymer morphologies (s, w or v)
Vary relative block volume fractions for rational design of particle size & shape
Effect of Particle Morphology on Flow Properties
Anisotropic worms produce free-standing gels
Entangled ‘worms’ hence higher viscosity?
=
An 8.0 w/v % aqueous solution of PGMA54PHPMA140
Cool
Heat
20oC < 5oC
This sol-gel thermal transition is fully reversible
Thermo-responsive Copolymer Worm Gels
A. Blanazs, A. J. Ryan, S. P. Armes et al., JACS, 2012, 134, 9741
What Causes Reversible Copolymer (De)gelation?
Degelation due to reversible worm -to-sphere transition!
Initial copolymer worms at 21 oC
TEM studies of a PGMA 54-PHPMA140 diblock copolymer:
A. Blanazs, A. J. Ryan, S. P. Armes et al., JACS, 2012, 134, 9741
Copolymer ‘spheres’are formed at 4 oC
Cool
Heat
Stem cells remain undifferentiated within worm gels for 14 days
With Dr. I. Canton and Prof. H. Moore, manuscript in preparation
Optical image of stem cell colonies
within a PGMA-PHPMA worm gel
Pluripotent stem cells receive no mechanical cues from worm gels
Ki-67 and statin bio-assays: worm gel induces stem cell stasis?
Sufficient time to ship human stem cells anywhere in the world?
Cell Biology Applications for Biocompatible Worm Gels
Stem cells readily isolated from worm gel via cold centrifugation
ABC Triblock Copolymer Syntheses via RAFT Seeded Emulsion Polymerisation
P. Chambon, A. Blanazs, G. Battaglia, S. P. Armes Macromolecules, 2012, 45, 5081
PGMA-PHPMA vesicles
BzMA
70oC
PGMA-PHPMA-PBzMA vesicles
PHPMA-PBzMAmixed vesicle
membrane ~ 95 % BzMA conversion in 2 h at 70oC; Mw/Mn < 1.50
Get micro-phase separation between PHPMA & PBzMA chains within membrane
G58-H360 G58-H360-B200 G58-H360-B300 G58-H360-B400
PISA: a versatile generic platform technology
Nanoparticle lubricants (Lubrizol)
Long-term storage of mammalian cells (GE Healthcare )
Next-generation gas-permeable contact lenses (GEO)
Microencapsulation applications (P & G)
Anti-reflective coatings for plastic substrates (DSM)
Improved thickeners (Scott Bader)
Bespoke nanoparticles for CaCO 3 occlusion (EPSRC)
New efficient Pickering emulsifiers (ERC)
ConclusionsSpherical block copolymer
nanoparticles prepared in water
Block copolymer worms obtained over a narrow copolymer composition range
Do worm gels have biomedical applications
for long-term storage of stem cells?
Worms form soft free-standing aqueous gels
Block copolymer worm gels are thermo-responsive
Acknowledgements: “Art is I, Science is We” (Claude Bernard)
Thank you for your attention
Prof. Norman Billingham (long-term collaborator at U. Sussex)
Prof. Tony Ryan OBE (long-term collaborator at U. Sheffield)
~ 50 PhD students and ~ 50 post-docs at U. Sussex and U. Sheffield
£££: EPSRC, ERC, The Royal Society and many industrial companies
Prof. Brian Vincent (PhD supervisor at U. Bristol)
Dr. Matt Aldissi (Post-doc supervisor at LANL, New Mexico)