PolyRMC, Tulane Center for Polymer
Reaction Monitoring and Characterization
Founded in Summer 2007
Mission statement:
To be the world’s premier center for
R&D
polymerization
reaction
monitoring
Motto:
Recently acquired lab space
Value and impact based on scientific
and technical excellence, integrity,
and relevance
Wayne F. Reed, Founding Director
Alina M. Alb, Associate Director for
Research
Michael F. Drenski, Associate Director
for Instrumentation
Alex Reed, Assistant Director for
Operations
Aerial view of Tulane campus
http://tulane.edu/sse/polyRMC
PolyRMC is a non-profit entity
: Tightly focused but broadly applicable
Multi-detector
SEC analysis:
Industrial R&D
and problem
solving
Multi-angle Light Scattering,
Viscometer, RI, UV detectors
Advanced characterization
Monitoring and control
‘on-command’
polymers
Resins, Paints, Coatings
Accelerate R&D
of new materials
Fundamental and applied research
• new polymeric materials
• medical applications
• nanotechnology
• new high performance materials
Polymer ‘born characterized’
Through PolyRMC personnel’s many years of industrial collaboration the process of
dealing with confidentiality, intellectual property rights, and all other legal issues has
been streamlined to produce rapid agreements on desirable terms for industries.
Some of PolyRMC’s Initiatives
Fast Turn-around polymer characterization
• Reduce bottlenecks and lengthy turn around time in workflows.
• The services can be used to prioritize and complement each industry’s own
in-house characterization efforts.
• Set standards of quality control and product reproducibility leading to
higher efficiency, and establish means of characterizing and improving new
products.
R&D, product development, and problem solving in
the polymer/pharmaceutical/ natural products
industries
• failure to meet product grade specifications;
• inconsistency of product quality;
• product instabilities, such as precipitation, degradation, or phase
separation;
• Defects in the products, such as colloids, particulates, and undesirable
colors;
Development of natural products
• Release of proteins, polysaccharides, and other components
during extraction, including enzymatic
activation/deactivation processes.
• Monitoring chemical and physical changes when natural
products are modified by chemical, thermal, radiative, or
enzymatic treatments.
• Determining the types of micro- and nanostructures that can
be formed from natural products.
• Measurement of encapsulation and time-release properties
of natural products used with pharmacological, food, and
other substances.
PolyRMC Expertise
◦ Deep expertise broadly applicable to applied polymer issues;
creativity; advanced instrumentation base; entrepreneurial
energy
◦ Adapting our approaches to the many complex processing aspects
of natural products; extraction, enzymatic modifications,
chemical tailoring, encapsulation, etc.
◦ A track record of success in solving problems:
e.g. - gelatin/oligosaccharide phase separation
- aggregation, degradation, micro-gelation, dry powder dissolution,
polymerization
- characterization of natural products; xanthan, pectin, gum arabic,
alginates;
- multi-detector SEC characterization;
- origin and detection of polymer product anomalies;
- determination of physical/chemical processes in production of
copolymers;
- characterization of water soluble polymers for water purification,
paints, cosmetics, food;
Advantages
•
Deep and powerful expertise in highly focused but broadly
applicable areas
•
Ability to conceptualize problems in general, far-reaching
terms
•
Complete, state-of-the-art instrumentation and skills within a
‘clean’ university environment
•
Ready access to many online resources
•
Chance to outsource research and problem solving without the
overhead investment
•
PolyRMC is used to dealing with industrial partners and their
concerns for IP rights, confidentiality, etc.
Types of reactions that we monitor
• Synthetic polymerization reactions: free radical, ‘living’, polycondensation,
homogeneous and emulsion phase, in batch, semi-batch, and continuous
reactors
• Postpolymerization reactions: hydrolysis, PEGylation, ‘click’ reactions,
grafting, amination, etc.
• Modifications of natural products, especially polysaccharides
• Poplypeptide synthesis reactions
• Oligonucleotide synthesis reactions
• Polymer degradation reactions due to enzymes, chemical agents, heat,
radiation, acids, bases, etc.
• Protein aggregation and other instabilities
• Phase separation, microgelation
• Kinetics of interacting components in complex solutions
• Dissolution of dry powders, emulsions, pastes, etc.
• Release of encapsulated and associated agents
• Production or hydrolysis of polymers amidst bacterial populations
The types of quantities and events that we
monitor during these reactions

Evolution of polymer molecular weight

Reaction kinetics; e.g. polymerization, degradation, aggregation rates

Particle size distributions

Degree of reaction completion

Tracing residual monomers and other reagents

Monomeric and comonomeric conversion

Reactivity ratios

Composition drift and distribution

Intrinsic viscosity

Unusual or unexpected events during reactions; onset of turbulence,
microgelation

Attainment of desired properties, such as stimuli responsiveness;
ability to encapsulate drugs or other agents, micellization or other
supramolecular structuration, solubility changes, ability to interact or
not interact with specific agents, etc.
Methods and techniques used for reaction
monitoring and characterization
Equilibrium characterization of polymer solutions
• Multi-detector Size Exclusion Chromatography (SEC), a
standard method
• Automatic Continuous Mixing (ACM), characterize complex,
multicomponent solutions along selected composition gradients. A
PolyRMC method.
Non-equilibrium characterization; PolyRMC methods
• ACOMP (Automatic Continuous Monitoring of
Polymerization reactions); Monitor synthetic reactions, polypeptide
synthesis, polymer modifications, etc.
• Heterogeneous Time Dependent Static Light Scattering
(HTDSLS); Characterize co-existing populations of polymer and
colloids; e.g. bacteria and polymers
• Simultaneous Multiple Sample Light Scattering (SMSLS);
high throughput screening of protein aggregation, solution stability in
general.
Achtung!
Do not use equilibrium characterization
methods to characterize nonequilibrium systems.
Many biological polymers in aqueous solutions are inherently
unstable and can aggregate, form microgels, precipitate, or otherwise
degrade in time.
• The time for such instabilities may be seconds, hours, days, even
months or longer.
• It is hence imperative to know if such a solution is in equilibrium, or
at least in a long lived metastable state, before making equilibrium
measurements, such as chromatographic determinations, or single
scattering or other measurements.
• This is why we have developed a number of methods, briefly outlined
below, SMSLS, ACOMP, ACM, and HTDSLS, for monitoring the
kinetics and characteristics of non-equilibrium processes.
• Unfortunately, many researchers spend a lot of time making
measurements on kinetically unstable systems, leading to
irreproducible results and confusion.
Multi-detector size exclusion
chromatography; to be used when
the polymer solution is in equilibrium
Example of state-of-the art multi-detector Size
Exclusion Chromatography
Determining the molecular origins of how a natural product works
to emulsify and thicken alimentary products.
Analyzed gum arabic SEC data
bulk
viscosifying
emulsifying
SEC: Origin of oligosaccharide/gelatin phase
separation
It’s the oligosaccharide, not the gelatin!
Dextran has a small population of very high mass chains causing
separation:
Mn=1,600g/mole
Mw=12,500g/mole
Mn controls the sensation
of sweetness, and
determines commodity
price, but Mw controls
phase separation. This
approach provides a means
of screening this highly
variable natural product.
RI & LS90o (arb. units)
- Seen in SEC light scattering
Monitoring polymer degradation
processes
Light Scattering and Degradation
Signatures for time dependent light scattering
enzymatic degradation of linear molecules with different
numbers of strands
Degradation by laminarinase
time [104 sec]
Beta glucan is a
mixture of double
and triple strands
New signatures for time-dependent light scattering
degradation of branched polymers; determination of
polymer architecture, kinetics, modes of cleavage
glycosaminoglycan sidechains
protein backbone
Proteoglycan ‘monomer’
- sidechain stripping, backbone intact
- random sidechain degradation, backbone intact
- sidechain stripping and backbone degradation
sidechain stripping
random chain cleavage
random backbone cleavage
Simultaneous Multiple Sample Light
Scattering (SMSLS); when high
throughput and/or long term solution
stability screening is important
Simultaneous Multiple Sample Light Scattering
SMSLS: High throughput screening
A typical SMSLS
prototype with both
flow and batch cells
A single instrument can monitor stability and reactions of many
different samples for hours, days, months, automatically, and with
a single computer; e.g. Monitor protein aggregation.
SMSLS scheme for automatic, continuous
monitoring of protein aggregation
N= # of parallel cell
banks
M= # of series cells
NxM protein samples under
any desired set of T, pH,
concentration, agitation, ionic
strength
Mw vs. time for all NxM
samples, continuously and
simultaneously on the
computer screen
Note, for aggregating systems that become turbid M =1
Developing and delivering complete SMSLS
systems to Pharmaceutical companies;
How technology transfer will work
PolyRMC will run assays on systems determined by pharmaceutical
sector colleagues, e.g. protein solution stability under a matrix of
conditions.
If SMSLS proves useful for a given pharmaceutical sector collaborator,
PolyRMC, or associated entity, will build and deliver a turn-key,
customized SMSLS instrument and associated software for the
collaborating company.
PolyRMC also provides an as-needed access service to SMSLS assays,
and related problem solving, in cases where the company might not
need an instrument of its own.
Online monitoring/characterization
of aggregation processes
Gelatin aggregation
Aggregation process for gelatin solutions at different temperatures,
monitored by ACOMP
Protein aggregation
Therapeutic protein aggregation monitored by SMSLS
All solutions are unstable
over time
Mapp. / Mapp., t=0
-at ionic strength:
1.56 – 50mM
t (h)
Ranked methods for monitoring and
quantifying protein aggregation
Most important aspect of aggregation is change
in Mass
1. Static Light Scattering:
Absolute, model-independent
change in Mw at the slightest change
SMSLS: for high throughput
2. Dynamic Light Scattering: Runner-up. Model
dependent, sensitive to <D>z, only indirectly sensitive to
Mass.
3. Low angle Mie scattering/diffraction: e.g. Master Sizer. Misses
the boat. Reports aggregation only after very advanced. Gives
‘size’ not mass.
4. Fluorescence. Indirect, insensitive, but better than nothing.
Enzymatic degradation monitored by SMSLS
Hyaluronate degradation by hyaluronidase
Rapid determination of
enzyme kinetics
Michaelis-Menten-Henri Enzyme
kinetics
1/v=1/v
+K /cv
max
m
max
1 1011
y = 6.2873e+09 + 8.9157e+06x R= 0.99696
10
8 10
1/v
10
6 10
10
4 10
Vmax=1.6x10-10 M/s
2 1010
Kmax=0.00142 cm3/g
0
0
2000
4000
6000
1/c
8000
1 104
1.2 104
Dissolution of polymers
and time release studies
Dissolution of a polyelectrolyte
* Small population of aggregates present in dry powder
* Aggregates dissolve in time
Polystyrene sulfonate
Dissolution of dry polysaccharides
Origin of poor dissolution due to formation of aggregates
Monitoring drug release by nanohydrogels
Poly(acrylonitrile-co-Nisopropylacrylamide), p(AN-c-NIPAM) coreshell hydrogel nanoparticles were synthesized by microemulsion
polymerization and their feasibility as drug carrier was investigated.
The release of propanolol, PPL from core-shell p(AN-c-NIPAM) 1” and
amidoximated p(AN-c-NIPAM) “2” was continuously monitored by
UV detection with ACM.
(a)
OH
OCH2CHCH2NHCH(CH3)2.HCl
CN
Acrylonitrile
Ethylene Glycol
Dimethacrylate
N-isopropylacrylamide
Relesed amount drug(mg)
0.25
(b)
0.2
(2)
0.15
(1)
0.1
0.05
0
0
1
2
3
4
5
Time (h)
6
7
8
Monitoring heterogeneous solutions of
polymers and colloids; e.g. proteins
amidst bacteria.
Heterogeneous Time Dependent Static
Light Scattering (HTDSLS)
Applications of Heterogeneous Time Dependent
Static Light Scattering (HTDSLS)
HTDSLS: Use flow to create countable scattering peaks from
colloidal particles, while simultaneously monitoring the
background scattering due to co-existing polymers
Determine large particle densities amid polymer chains; e.g.
spherulites, microgels, bacteria, crystallites, etc.
Follow evolution of large particles; e.g. in biotechnology reactors
where bacteria/polymers co-exist. e.g. xanthan productions,
degradation of polysaccharides, other fermentation reactions
Permits useful characterization of polymers in solutions which, up
until now, would be considered far too contaminated with dust and
other scatterers.
HTDSLS: Good data from a classically intractable case of
high particulate contamination:
1500
5200, 2 micron latex spheres/mL
[PVP]
.
1. 5 mg/ ml
BL 856mV.
.
.
1 mg/ ml
BL 630mV.
0. 75 mg/ ml
BL 513mV.
.
.
.
0. 25 mg/ ml
BL 213mV.
.
.
wat er
BL 25mV
I(mV)
1000
500
0. 3205
0. 3596
0. 4328
0. 4333
av 0. 40 + 14%
0
3.4x10-6
0
50
100
150
3.2x10-6
200
250
t(s)
-6
3.0x10
2.8x10-6
2.6x10-6
Kc/I
F( 1/ s)
0. 4561
Mw=6.1x105 g/mol
A2=3.34x10-4mLmol/g2, Rg=460 A
2.4x10-6
2.2x10-6
2.0x10-6
1.8x10-6
1.6x10-6
1.4x10-6
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
sin^2( /2) + 100*c
0.8
0.9
1.0
1.1
1.2
Schimanowsky, Strelitzki Mullin, Reed,
Macromolecules 32, 7055, 1999
300
350
Heterogeneous time dependent static light
scattering (HTDSLS)
Co-existing E. Coli and PVP polymers in solution
Schimanowsky, Strelitzki Mullin, Reed, Macromolecules 32, 7055, 1999
Automatic Continuous Online
Monitoring of Polymerization
reactions (ACOMP)
Automatic Continuous Online Monitoring
of Polymerization reactions: ACOMP

Fundamental studies of polymerization
kinetics and mechanisms

Optimization of reactions at bench and
pilot plant levels

Full scale, feedback control of industrial
reactors
Principle of ACOMP
Continuously extract and dilute viscous reactor liquid producing
a stream through the detectors so dilute that detector signals are
dominated by the properties of single polymers, not their
interactions.
ACOMP ‘front-end’:
Extraction/dilution/co
nditioning
ACOMP ‘back-end’:
Detector train
Light scattering
Reactor
Viscometer
Refractive index
detector
Solvent
UV detector
About ACOMP
- Monitor important characteristics of polymerization
reactions while they are occurring
- Develop new polymeric materials, understand
kinetics and mechanisms.
- Optimize reactions at bench and pilot plant
level.
- Full feedback control of large scale reactors:
Increased energy efficiency
More efficient use of non-renewable
resources, plant and personnel time
Less emissions and pollution
Stem the flight of manufacturing overseas: Jobs.
Recent ACOMP advances

Copolymerization

Predictive control

Heterogeneous phase; emulsion and
inverse emulsion

Living-type polymerization

Continuous reactors
ACOMP lab. unit
Emulsion Polymerization: Example of raw data and analysis
- first simultaneous online monitoring of both polymer and particle
properties
Raw data and analysis for free radical polymerization of MMA in emulsion at 70C.
Left: polymer Mw and hr vs. conversion; Right: particle size distribution and specific surface area
A. M Alb, W. F Reed, Macromolecules, 41, 2008
Summary: PolyRMC works with many pharmaceutical,
synthetic, and natural product polymers, with a particular
emphasis on monitoring processes in solutions of these in
order to
•
Better understand the processes and mechanisms
involved in producing such polymers
•
Quantitatively control the factors responsible for the
reactions
•
Monitor processes for completion, unusual events,
specific thresholds of product stimuli
responsiveness, etc.
•
Produce products that consistently meet or exceed
specifications.
•
These capabilities can be used in the discovery,
development, formulation, and quality control stages