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Watkins Research GroupGraduate students: Yiliang Zhou, Benjamin Yavitt, Wenhao Li, Gayathri Kopanati, Xiyu Hu, Sravya Nuguri, Vincent Einck, Hsin-Jung Yu
Postdocs & staff: Janghoon Park, Jacobo Morère Rodriguez, Hua-Feng Fei, Yuying Tang, Uzodinma Okoroanyanwu
Polymer Science and Engineering ~ University of Massachusetts Amherst
Our team is comprised of graduate students, post-docs and senior scientists with diverse technical backgrounds including polymer
science and engineering, materials science, chemical engineering, electrical engineering and chemistry. We develop, characterize and
utilize nanoscale and hybrid materials for the fabrication of devices that exploit the unique properties of the materials that we create.
Fundamentals of Brush Block Copolymers Solvent-Assisted Soft Nanoimprint Lithography
Optical and Energy Devices Flexible Hybrid Electronics and Roll-to-Roll Fabrication
Lithium-ion battery
ACS Appl. Mater. Interfaces. 10, (2018), 5447–5454.
3-D woodpile electrodes
Slide ring-elastomer strain sensor
1μm
ACS Applied Materials & Interfaces. 7, 6 (2015), 3641-3646.
Plasmonic grating structures of TiN
Journal of Materials Chemistry C. 6, (2018), 1399-1406.
Roll-to-roll processing of nanomaterials
High-performance organic inverters Wearable microfluidic sweat sensors
Phase behavior
No Shear120 C, 1 hr.
Oscillatory Shearω = 1 rad/s, γ = 50 %
145 C, 6 hr.
PS(2.9k)-b-PEO(5k)
• Lamellae align with controlled oscillatory shearing
• Parallel orientation (S ~ 0.8) achieved over several mm3
• Facilitated by high molecular mobility in melt
• Lamellar morphology
• d-spacing ~ 50 nm
• Bulk sample ~ mm3
In preparation
Controlling domain alignment with shear
~ 2 mm
Macromolecules. 2017, 50, 396
Anneal 1 h at 120 C Anneal 24 h at 120 CMicrophase
Separated
Morphology
G* (Pa)
♦ fPEO = 0.22
♦ fPEO = 0.47
♦ fPEO = 0.81Entanglement Plateau
Elastic Terminal● fPEO = 0.24
● fPEO = 0.49
● fPEO = 0.81
G* (Pa)
Tan δ
No Entanglement
Viscous Terminal
Tan δ
Brush BCP Linear BCP
“Glassy”
“Glassy”
Rheology of PS-b-PEO BBCP & LBCP
Rheology
Functional hybrid materials via self-assembly of brush block copolymers
• Mesopore size: 44-48 nm• Macropore size: > 50 nm• Uniform & Interconnected• Large Area Nanoporous Films• Flexible Substrate (PET)• Low Temperature Processing• Sub-Millisecond Treatment
J. Am. Chem. Soc. 2016, 138, 13473-13476
Mesoporous silica carbon hybrids
Tunable spacing (40-140 nm)
High loading of 30 wt.% CdSe
Well-Ordered Lamellae
Strong Photoluminescence
Macromolecules. 2016, 49, 5068-5075
Nonlinear optical materials
• Large Refractive Index Contrast – (> 0.27)
• Selectively High Loading of NPs – (42 vol.%)
• Tune Refractive Index from 1.45 to 1.70
• Enhanced Reflection at 398 nm (~ 250 %)
ACS Nano. 2016, 10, 1216-1223
High Δn photonic crystals
• Large Domain Spacing: 120-260 nm
• Visible to near-IR region: 458-1010 nm
• Tunable NP Loading
• High Loading ~ 80 wt.%
Adv. Optical Mater. 2015, 3, 1169-1175
Metal-dielectric metamaterial
Chemistry of Materials 2017, 29, 3908−3918
Imprint lithography and conformal metallization
Bioinspired shark-skin surfaces for antimicrobialPatterned 2D & 3D metal oxide nanostructures
Cellulose 2018 25: 5185
Patterned submicron scale cellulose film
10.1021/acsami.8b01302
dim
atix.com
In preparation
Glucose sensor with inkjet-printed electrodes
10.1021/acsami.8b01302
R2R nanoimprinting process
• R2R UV-NIL tool
• Sub 50 nm features and feet per minute rates
• Rapid fabrication of optical & antimicrobial patterns
Rapid photothermalcuring
BCP/metal NPs/carbon sources Mesoporous carbon structures
PET roll
Coated carbon precursor layer
Microgravure
Infrared dryer
Dried film(polymerization)
Xenon lamp
Carbonized film for electromagnetic interference (EMI) shielding
R2R coating and photothermal processing
Nano Energy. 52, (2018), 431–440.
In Preparation
Copolymer gel eletrolytesConformal iCVD coating of copolymer electrolytes
ACS Appl. Mater. Interfaces, 2018, 10 (9), pp 8173–8179
10.1021/acsami.8b01302
ACS Appl. Mater. Interfaces, 2018, 10 (18), pp 15988–15995
Brush block copolymer properties
Short Side Chains
Extended Backbone
Reduced Chain Entanglement
High Molecular Mobility
• Rapid self-assembly (< 5 min)
• High loading of functional additives (> 70 wt.%)
• Large lattice parameters (> 100 nm)
• Macroscopic ordering (mm3 scale)
Phase behavior
Phase maps
In preparation