Transparent, Abrasion Resistant Polymer For Durable Microstructures
Transparent, Abrasion Resistant Polymer For Durable Microstructures
(OP)
I need to mold microstructures in a thin film of material where the microstructures consist of an array of microposts that are 40um in diameter, 40-60um tall, and spaced by 80um. The structured thin film must be transparent (>90% transmission over visible wavelengths), durable, and scratch resistant (not abraded by cheesecloth).
I have tried using hard and elastic urethanes. Microstructures made of hard, brittle materials tend to fracture, whereas microstructures made of more tough, elastomeric urethanes do not break, but become hazy when scratched by cheesecloth.
Can anyone suggest materials (and/or fillers) to use in this application to make a tough, durable, scratch-resistant, and transparent microstructured surface?
I have tried using hard and elastic urethanes. Microstructures made of hard, brittle materials tend to fracture, whereas microstructures made of more tough, elastomeric urethanes do not break, but become hazy when scratched by cheesecloth.
Can anyone suggest materials (and/or fillers) to use in this application to make a tough, durable, scratch-resistant, and transparent microstructured surface?





RE: Transparent, Abrasion Resistant Polymer For Durable Microstructures
Brittle materials are out because they will break. Elastomers should work because they deform and bounce back undamaged.
The PU probably becomes hazy because it picks up lint from your cloth. Does it regain transparency when you clean it thoroughly? I.e. water, detergent and an ultrasonic bath.
Chris DeArmitt
"Knowledge has no value except that which can be gained from its application toward some worthwhile end."
Think and Grow Rich - Napoleon Hill
RE: Transparent, Abrasion Resistant Polymer For Durable Microstructures
I forgot to mention that we did try polydimethylsiloxane, but the posts tended to tear from surface during the durability/scratch tests.
Rinsing and sonicating the PU in isopropyl alcohol removed some of the haze. We looked at the PU under a microscope and it appeared to have been physically scratched by the cheesecloth.
Any thoughts on how to make the current PU more scratch resistant? Are there any elastomers or PUs you might suggest trying?
RE: Transparent, Abrasion Resistant Polymer For Durable Microstructures
Place all plaques flat on the inside of a drum (old biscuit tin etc), add sand or other abrasive, in your case some shredded cheese cloth plus some ceramic milling beads for weight). Then rotate the whole thing at your expected abrasion speed and measure loss in gloss over time. This reveals the most abrasion resistant materials fast. I have introduced this to two companies who now swear by it.
Then take your top candidates and test with the microstructured surface. Cross-link density and Tg of the elastomer are critical. Materials that are elastomers may no longer be elastomeric at the speeds used in your abrasion test (see the WLF equation). This is really important.
Chris DeArmitt
"Knowledge has no value except that which can be gained from its application toward some worthwhile end."
Think and Grow Rich - Napoleon Hill
RE: Transparent, Abrasion Resistant Polymer For Durable Microstructures
1)R.M.Evans and J.Fogel:J. Coat. Technol., 49[634],
p.50(1977)
Chris DeArmitt
"Knowledge has no value except that which can be gained from its application toward some worthwhile end."
Think and Grow Rich - Napoleon Hill
RE: Transparent, Abrasion Resistant Polymer For Durable Microstructures
Regards
Pat
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RE: Transparent, Abrasion Resistant Polymer For Durable Microstructures
Chris DeArmitt
"Knowledge has no value except that which can be gained from its application toward some worthwhile end."
Think and Grow Rich - Napoleon Hill
RE: Transparent, Abrasion Resistant Polymer For Durable Microstructures
h
http://www.permalac.com/technicalfacts.asp