Alec B. Scranton

Research Interests:
photopolymerization
microlithography
reversible emulsifiers
polymerization kinetics

Website: Center for Fundamentals and Applications of Photopolymerization

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Fundamental Characterization of Photopolymerization
Photopolymerizations are chain reactions in which a liquid monomer is converted to a solid, durable polymer in a process that is triggered by light of the appropriate wavelength. The use of light, rather than heat, to drive a polymerization reaction offers some important advantages that can be exploited to develop new processes or products. For example, photopolymerizations provide both spatial control and temporal control of the reaction since light can be directed to locations of interest in the system and is easily shuttered on or off. In addition, photopolymerizations provide solvent-free formulations, (which reduce the emissions of volatile organic pollutants) and exhibit extremely rapid reaction rates. These advantages have led to tremendous growth in the application of photopolymerizations in the private sector (~20% annual growth), however much of this growth has occurred without a fundamental understanding of the underlying chemical processes. My research is providing a comprehensive characterization of the kinetics, mechanisms, structure and properties of photopolymerizations. Our work in this area includes the following types of studies:

• Characterization of the photochemical processes by which polymerizations may be initiated.
• Kinetic characterization of cationic Photopolymerization.
• Development of methods for photopolymerization of thick polymers and composites.
• Development of photopolymerization systems based upon agricultural feedstocks.
• New methods for monitoring high-speed photopolymerization reactions.

Reversible Emulsifiers Based upon Polymer Complexation
We have developed a new class of reversible emulsifiers that allow oil-in-water emulsions to be formed and broken at will. Block copolymers containing alternating hydrophilic and hydrophobic segments are widely used as stabilizers for aqueous emulsions. In these polymers, the hydrophobic block is designed to penetrate into the oil phase, while the hydrophilic block extends into the aqueous phase. A prominent example of block copolymer emulsifiers are ethylene oxide/propylene oxide diblock and triblock systems, and all known emulsifiers of this type contain permanently hydrophobic segments. We developed a new approach for designing emulsifiers in which the hydrophobic blocks are formed spontaneously and reversibly by complexation of two hydrophilic segments of a comb-type graft copolymer. Unlike current emulsifiers, this new approach allows emulsions to be broken at will, with the hydrophobic segment of the emulsifier becoming completely water soluble in a reversible manner that does not involve chemical degradation.

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Selected Publications (from over 60)

K.K. Baikerikar, V. Sipani, C.N. Coretsopoulos, and A.B. Scranton, "Photopolymerization of Silica-Filled Composites: Encapsulants for Microelectronic Devices," ACS Symposium Series, in press.

K.S. Padon, D. Kim, M. El-Maazawi, and A.B. Scranton, "Spectroscopic Investigation of Three Component Initiator Systems," ACS Symposium Series, in press.

J.L.P. Jessop, S.N. Goldie, A.B. Scranton, and G.J. Blanchard, "Spectroscopic Characterization of Acid Generation and Concentration and Free Volume Evolution in Chemically Amplified Resists," J. Vac. Sci. Technol. B, in press.

V. Sipani, C.N. Coretsopoulos, and A.B. Scranton, "Photopolymerization of Composite Materials," Research Trends, in press.

G.A. Miller, L. Gou, V. Narayanan, and A.B. Scranton, "Modeling of Photobleaching for Photoinitiation of Thick Polymerization Systems," J. Polym. Sci. Polym. Chem., 40, 793, 2002.

K.K. Baikerikar and A.B. Scranton, "Photopolymerizable Liquid Encapsulants for Microelectronic Devices: Thermal and Mechanical Properties of Systems with Reduced In-Mold Cure Times," J. Appl. Polym. Sci., 81, (14), 3449-3461, 2001.

K.S. Padon and A.B. Scranton, "A Mechanistic Investigation of the Three-Component Radical Photoinitiator System Eosin Y Spirit Soluble, N-methyldiethanolamine, and Diphenyliodonium Chloride," J. Polym. Sci., Polym. Chem., 39, 715, 2001.

B. Drescher and A.B. Scranton, "Synthesis and Characterization of Polymeric Emulsifiers Containing Reversible Hydrophobes: Poly(methacrylic acid-g-ethylene glycol)," Polymers, 42, 49, 2001.

K.K. Baikerikar, and A.B. Scranton, "Photopolymerizable Liquid Encapsulants for Microelectronic Devices," Polymer, 42, 431-441, 2001.

Brian J. Elliott, Alec B. Scranton, James H. Cameron, and Christopher N. Bowman, "Characterization and Polymerization of Metal Complexes of Poly(ethylene glycol) Diacrylates and the Synthesis of Polymeric Pseudocrown Ethers," Chem. Mater., 12, 633, 2000.

K.S. Padon and A.B. Scranton, "The Effect of Oxygen ont he Three-Component Radical Photoinitiator System Methylene Blue, N-Methyldiethanolamine, and Diphenyliodonium Chloride," J. Polym. Sci, Polym. Chem., 38, 3336, 2000.

K.S. Padon and A.B. Scranton, "A Mechanistic Investigation of the Three-component Radical Photoinitiator System Methylene blue, N-Methyldiethanolamine, and Diphenyliodonium Chloride," J. Polym. Sci, Polym. Chem. , 38, 2057, 2000.

A.M. Mathur, B. Drescher, A.B. Scranton, and J. Klier, "A Polarity-Sensitive Fluoresence Study of the pH-Dependent Aggregation of Poly(mathacrylic acid-g-ethylene glycol) Copolymers in Water," Spectroscopy, 15(4), 36, 2000.

K.K. Baikerikar and A.B. Scranton, "Viscosity Characterization of Highly Filled Photopolymerizable Liquid Encapsulants for Microelectronic Devices," Polymer Composites, 21, 297, 2000.

K.S. Padon and A.B. Scranton, "Recent Advances in Three Component Photoinitiators," Recent Res. Devel. Polymer Science, 3, 369, 1999.

A.B. Scranton, R.M. Russell, N. Basker, J.L.P. Jessop, and L.C. Scranton, "Teaching Material and Energy Balances on the Internet,"ASEE National Conference Proceedings, CD-ROM edition, June 1999.

A.M. Mathur and A.B. Scranton, "Synthesis and Ion-Binding Properties of Polymeric Pseudocrown Ethers III: Ion Binding Studies," Sep. Sci. and Technol., 34, 855, 1999.

P. Kohli, A.B. Scranton, and G.J. Blanchard, "Copolymerization of Maleimides and Vinyl Ethers: A Kinetic and Structural Study," Macromolecules, 31, 5681, 1998.

A.M. Mathur, K.F. Hammonds, J. Klier, and A.B. Scranton, "Equilibrium Swelling of Poly(methacrylic acid-g-ethylene glycol) Hydrogels: Effect of Swelling Medium and Synthesis Conditions," J. Control. Rel., 54, 177, 1998.

A.M. Mathur, B. Drescher, J. Klier, A.B. Scranton, "Polymeric Emulsifiers Based on Reversible Formation of Hydrophobic Units," Nature, 392, 367, 1998.

V. Narayanan and A.B. Scranton, "Photopolymerizations of Composites," Trends in Polymer Science, 5, 415, 1997.

L.S. Coons, B. Rangarajan, D. Godshall, and A.B. Scranton, "Photopolymerization of Vinyl Ester - Glass Fiber Composites," ACS Symposium Series, 673, 203, 1997.

A.M. Mathur and A.B. Scranton, "Synthesis and Ion-Binding Properties of Polymeric Pseudocrown Ethers II: Template Ion Induced Cyclization of Oligomeric Ethylene Glycol Diacrylates," Sep. Sci. and Technol., 32, 285, 1997.

E.W. Nelson and A.B. Scranton, "In Situ Raman Spectroscopy for Cure Monitoring of Cationic Photopolymerizations of Divinyl Ethers," J. Raman Spectroscopy, 27, 137, 1996.

A.M. Mathur, S.K. Moorjani, and A.B. Scranton, "Methods for Synthesis of Hydrogel Networks: A Review," J. Macromol. Sci, Rev. Macromol. Chem Phys., C36, 405, 1996.

B. Rangarajan, L.S. Coons, and A.B. Scranton, "Characterization of Hydrogels Using Luminescence Spectroscopy," Biomaterials, 17, 649, 1996.

E.W. Nelson and A.B. Scranton, "Kinetics of Cationic Photopolymerizations of Divinyl Ethers Characterized Using In Situ Raman Spectroscopy," J. Polym. Sci. Polym. Chem, 34, 403, 1996.

A.M. Mathur and A.B. Scranton, "Characterization of Hydrogels Using Nuclear Magnetic Resonance Spectroscopy," Biomaterials, 17, 547, 1996.

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Patents

A.B. Scranton, B. Rangarajan, and K.K. Baikerikar, "Photopolymerizable Encapsulants for Microelectronic Devices," U.S. Patent No. 6,099,783, issued August 8, 2000.

R.W. Worden and A.B. Scranton, "Method for Forming Reversible Colloidal Gas or Liquid Aphrons and Compositions Produced." U.S. Patent No. 6,022,727, issued February 8, 2000.

A.B. Scranton, B. Rangarajan, and L.S. Coons, "Thick Composite Parts made From Photopolymerizable Compositions and Methods for Making Such Parts," U.S. Patent No. 5,855,837, issued January 5, 1999.

A.B. Scranton, A.M. Mathur, and J. Klier, "Emulsifiers and Thickeners Comprising Reversible Hydrophobic Functionalities," U.S. Patent No. 5,844,039, issued December 1, 1998.

A.B. Scranton, A.M. Mathur, and J. Klier, "Polymers Comprising Reversible Hydrophobic Functionalities," U.S. Patent No. 5,739,210, issued April 14, 1998.

G.J. Blanchard, J.L. Jessop, and A.B. Scranton, "Apparatus for in situ, Noninvasive Polymer Cure Determination," U.S. Patent No. 5,707,587, issued January 13, 1998.

G.J. Blanchard, J.L. Jessop, and A.B. Scranton, "Method for in situ, Noninvasive Polymer Cure Determination," U.S. Patent No. 5,633,313, issued May 27, 1997.