Here to View a Letter from the Advisory Committee
Why join the Photopolymerization
is one of the most rapidly expanding processes for materials production
with more than 20% annual growth. Photopolymerizations have gained
prominence in recent years for the pollution-free curing of polymer
films as well as emerging applications in dental materials, electronic
and optical materials, conformal coatings, and high resolution rapid
prototyping of 3D objects. These solvent-free polymerizations proceed
very rapidly with a fraction of the energy requirements of thermally
cured systems, and the resulting polymeric materials possess extremely
useful properties. For example, these reactions can be used to form
highly crosslinked, thermally stable polymer films exhibiting excellent
adhesion, abrasion resistance and chemical resistance while not emitting
or requiring volatile organic components. In addition to the broad
utility of the polymers that are formed, the photopolymerization process
itself affords many advantages, including very high reaction rates
at room temperature, spatial control of the polymerization, low energy
input and chemical versatility, since polymerization of a wide variety
of monomers can be initiated photochemically.
Due to the advantages
outlined above, photopolymerizations are playing an increasingly important
role in a variety of industries; therefore, the IUCRC will seek broad-based
support from a variety of companies representing both established
and emerging applications of photopolymerizations. For example, photopolymerizations
are firmly established as the method of choice for continuous, high-speed
coating operations. These applications range from web processes in
which an organic coating is placed onto a paper or plastic substrate,
to optical fiber coating systems in which an extremely high-speed
reaction is required to place a protective coating onto a glass fiber
being pulled at rates exceeding 100 feet per second. For these applications,
it is imperative that the polymerization kinetics are well understood
since the coating must be cured to a tack-free level before the process
is complete. Therefore, the information provided by the fundamental
kinetic and mechanistic studies to be carried out in the center will
provide information that will allow the companies to optimize current
processes, and identify promising reaction systems for new processes.
category of companies with which the IUCRC will interact on established
applications of photopolymerizations are resin and initiator suppliers.
These companies provide the reactive materials that the end-users
employ in applications. These suppliers are constantly developing
innovative new reactive systems that offer advantages over the traditional
formulations; therefore, the IUCRC would provide an invaluable service
to these companies by independently characterizing the kinetics of
these polymerizations as well as the thermal and mechanical properties
of the resulting polymers. In addition, since the IUCRC industrial
review board will include many end-users who would purchase raw materials
from these companies, the center would enhance the rate at which innovative
new systems are adopted within the industry.
to the established applications of photopolymerizations, center research
will be directed toward emerging applications of these reactions.
The goal of this high-risk, cutting-edge research is to expand the
applicability of photopolymerizations, demonstrating the utility of
these reactions in unexplored systems and processes. Examples of the
type of research include photopolymerizations of thick, fiber-filled
polymers and advanced, biomedical applications of photopolymerizations.
For example, in recent research the PIs have demonstrated two strategies
for effective photopolymerizations of thick (up to a few centimeters)
polymers and composites. The first strategy combines careful selection
of the initiating wavelength with the reactive system including the
resin/monomer, initiator formulation and their relative concentrations
to produce self-eliminating light intensity gradients.
Here, we ensure that the photochemical event which leads to the initial
light intensity gradient actually leads to its elimination. In the
second strategy, a hybrid photo/thermal initiating mechanism is employed
where the heat evolved from the highly exothermic photochemical reaction
elevates the temperature of the system such that a second, thermal
reaction occurs resulting in the production of additional active sites.
Similarly, the PIs of this proposal are developing new reaction systems
and strategies for sub-dermal photopolymerizations, intraoperative
curing of degradable polymers for frature fixation in orthopedics,
and custom production of devices using high speed, high resolution
3-D prototyping techniques.
class of industry that will be targeted by this IUCRC will be companies
involved with the microelectronic and liquid crystal display industries.
In these fields, the ability to control a polymerization (by spatially
directing the initiating light) plays a central role in the fabrication
process. An understanding of the underlying photochemical processes
is imperative in these emerging, high-tech applications (especially
with the advent of advanced, chemically amplified resists used in
deep-UV lithography). Therefore, the fundamental information obtained
in the IUCRC research will again play an enabling role for the optimization
of industrial processes.