Tests on PCHMA filmFilm at room temperature

(pre-test)Film at 150°C

(immediately after ramp)Film at 150°C

(soaked for 20min)0

Team Ocelot: Christina Engler, Brynn Lauer, Will Porter, Jacob Post | Advisor: Professor Wyatt Tenhaeff

Senior Design Fall 2016 | University of Rochester Department of Chemical Engineering

Introduction

Figure 2 : Relative Exam Performance Versus Relative Intrinsic Motivation.

References

• Previous research: Tg can be 10-30°C lower in ultrathin

films (< 100 nm thick) due to nanoconfinement effects.1

• Tg can be measured using polymer thermal properties

• Heat capacity

• Thermal expansion coefficient

• This design project developed an apparatus to measure Tg by

coupling thickness and temperature measurements

• An environmental chamber was built to heat ultrathin

polymer films and continuously monitor thickness using

specular reflectivity in a combined LabVIEW program

• Thickness measurement was performed using a FILMetrics

fiber optic and FILMeasure analysis software

1. Ediger, M. D., & Forrest, J. a. (2013). Dynamics near Free Surfaces and the Glass Transition in Thin

Polymer Films: A View to the Future. Macromolecules, 131127135402009.

2. Vourdas, N., Karadimos, G., Goustouridis, D., Gogolides, E., Boudouvis, A. G., Tortai, J. H.,

…Raptis, I. (2006). Multiwavelength interferometry and competing optical methods for the thermal

probing of thin polymeric films. Journal of Applied Polymer Science, 102(5), 4764–4774.

3. FILMetrics. (2016). F20 Series. Retrieved from

http://www.filmetrics.com/thicknessmeasurement/f20

4. Zeller, R. M., Walker, J. D., Wieland, K. a., & Compaan, a. D. (2009). Real-time Optical Thickness

Monitor for thin film growth. Photovoltaic Specialists Conference (PVSC), 2009 34th IEEE, (Figure 2),

1399–1401.

Control Program and Automation

Conclusions and Next Steps

Environmental Chamber for In-Situ Specular Reflectivity Measurements

Spectral Reflectivity

• A Vis-NIR light source is directed

at a sample and a detector

measures an interference pattern

• A model is fit to the pattern and

properties such as thickness and

refractive index are determined

Original Idea Final Design

FILMetrics

• A successful model fit requires a baseline to be obtained and a

recipe to be input into FILMeasure

• These both had to be saved to a file that is referenced by the

automation section of the LabVIEW code

Temperature Controller

• Controls the temperature of the stage where the

polymer film sits

• Uses a PID control-based feedback loop

• Generates an error based on the difference

between the surface temperature and the set-point

temperature for feedback control

• Power is supplied to cartridge heaters by square

wave signal generated by a sequence structure

• Can program a ramp procedure

Specify ramp rate and target temperature

• Can set program to soak sample at the target

temperature at the end of a temperature ramp

Specify soak (Y/N switch) and soak time

• Auto shut-off mechanisms in place to stop the

control program and turn off the power to the

cartridge heaters when the experiment is

considered complete

FILMetrics Automation

• FILMeasure provides the FIRemote public assembly that can be

referenced to automate measurements

• Used .NET programming environment in LabVIEW to access the

assembly and create instance of an FIRemote object

• A FILMeasure file with baseline and recipe is prepared before

running the program

• LabVIEW opens this file and continuously takes measurements,

allowing real-time coupling of temperature and thickness

measurements

• A device was built that can obtain thickness and

temperature measurements simultaneously while heating a

thin film at a specified heating rate

• A LabVIEW program was designed to control the system

• FILMeasure software fine-tuning can be done

• Working with FILMetrics application engineers to

set optimization parameters

• Ensuring accurate thickness measurements

• Tests on standard polymers with better defined thermal

properties to further characterize the abilities of the system

• Once the system is perfected, a long-term study of the glass

transition temperature (Tg) of PCHMA and other polymer

thin films can be performed

Data Acquisition• At lower temperatures, the

thickness increases with

temperature as expected from

thermal expansion

• The thickness rapidly decreases

and then fit fails above 100ºC

Problem Identification• Possible physical changes happening around 100ºC

• Vaporization of H2O in the film

• Other complex behaviors in PCHMA

• It is likely the window has an effect

• Not A/R coated or polished

• FILMetrics recipe can be fine tuned for a better analysis

Room Temp

Quartz window Quartz window removed

Room Temp

Immediately upon reaching 150ºC

Immediately upon reaching 100ºC

20 min soak at 150ºC

20 min soak at 150ºC

Environmental Chamber

• Aluminum 5” x 8” x 3”chamber

• Graphite Gasket Sealed Lid (top face of chamber)

• Removable Door with Gasket (front face of chamber)

Seals with Allen key closure around door

• 3” diameter Quartz window

• Adjustable Arm (optimizes distance between temperature

stage and light source) with the use of FILMetrics

Kinematic Mount (KM-GL25)

• Supported by ceramic standoffs

Cooling System

• Coupled with purge line system via a T-Swagelok

Allows for switching between nitrogen gas

and compressed air through the chamber

Adjustable Arm Window

FILMetrics Fiber Optic

Air N2

N2 outlet

Door with Gasket

N2 flow control

Oil bubbler

Solid State Relay

Fuse

Cartridge heater wires

Thermocouple wires

Electrical Feedthrough

N2 inlet

Kinematic Mount

Wiring from Temp Stage Temperature Stage

Ceramic Support

AcknowledgementsMany thanks to our advisor, Professor Wyatt Tenhaeff, for granting us this

project and offering indispensable insights throughout. Additionally, the team

would like to thank Rachel Monfredo, Cindy Fitzgerald, Thor Olsen, Larry

Kuntz, and Professor Doug Kelley for all the help, advice, and lessons they

have given us. This project would have not been possible without John

Miller’s help, so we would like to thank him as well. We are also very grateful

for our TA, Marina Ioanniti, and her continued support. Lastly, we are

grateful for all of the project support received from the FILMetrics engineers:

Dr. Jim Elman, Jarret Whetstone, and Rebecca Andrew.

Chamber Design

• The glass transition temperature

(Tg) is a critical physical parameter

in amorphous polymers

• Synthesis of ultrathin polymer thin

films is done in Professor Wyatt

Tenhaeff ’s lab

• prepared by initiated

Chemical Vapor Deposition

• polymer electrolyte layers

for lithium ion batteries

4VP PCHMA

Temperature Stage

• Aluminum 4” x 4” x ½” block

• 2 bored-through holes for cartridge heaters

• 1 hole for thermocouple ( Τ1 16”)

• Supported by ceramic standoffs

Nitrogen Purge Lines

• Maintains constant atmosphere (removes H2O and CO2)

• Oil Bubbler (prevents back diffusion)

Electrical Components

• Two 200 Watt, ¼’’ diameter cartridge heaters

• Cement-to-surface, Type K Thermocouple

• Τ1 16’’ diameter flexible Type K Thermocouple

• 10 Amp Solid State Relay

• T7 Series LabJack

2.

3.4. 5.

6.

7.

1.

2.

1. Open LabJack

2. Read temperatures

3. Ramp procedure

4. Error generation

5. % Duty Cycle out of PID loop

6. Square Wave Generation

7. Automatic Shut-Off Mechanism

Test on Poly(cyclohexyl methacrylate) iCVD film