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