Video Description for the Visually Impaired
Visual: still images illustrating specifically the applications the narrator is mentioning.
Narrator: Accurately measuring and quantifying the adhesive properties of materials to be used in, among many other applications, things like Scotch Tape…Post-It Notes…and sealants to keep moisture from getting behind auto headlights or help car doors stick together, is vital to providing products of highest quality.
Visual: researcher in lab setting up test to evaluate adhesive properties of materials.
Narrator: Developing versatile, flexible tests that evaluate the performance of such materials is part of the mission of the Polymers Division of the National Institute of Standards and Technology.
Visual: Chris Stafford on camera.
Text: Chris Stafford, PhD.
Research Chemist
National Institute of Standards & Technology
“Industry likes combinatorial methods because it allows them to conduct their experiments faster and more efficiently. So, they can do in one day what it used to take them multiple weeks to do. So, in a fast paced research environment, combinatorial methods are extremely valuable.
Combinatorial library is exactly what it sounds like. It’s every combination pf a particular variable in one sample and it looks like a library because you have a whole row or array of samples on one substrate.”
Visual: Peter Johnson on camera.
Text: Peter Johnson, PhD.
Chemical Engineer
National Institute of Standards & Technology
“My research concerns photopolymers so what I’m looking at for the research is the adhesive and time response capabilities of these photopolymers. So, how well they stick to certain surfaces and what that does, actually, over time.”
Text: Versatile Platform for Creating Gradient Combinatorial Libraries via Modulated Light Exposure
Visual: still image of banks of technologists doing screening
Narrator: Screening the cure time and intensity for UV coatings and adhesives arrays can be complex and time consuming.
Visual: researcher setting up screening in lab.
Narrator: However, a gradient in UV cure allows for rapid analysis of conditions all in one sample. It also allows for rapid analysis of sample conditions that, otherwise, would be difficult to perform.
Visual: shots of equipment to be used in screening.
Narrator: In short, new materials and formulations may require optimization of cure protocols that lie outside standard conditions.
Visual: Dental materials being tested on patient.
Narrator: Beyond that, existing technology cannot always be leveraged toward effective solutions for a new application.
Visual: researcher at computer; researcher setting up screening; screening equipment.
Narrator: Library fabrication can often present a primary--if not THE primary--obstacle to implementing “combi” for emerging material systems for an increasingly fast-paced industrial research environment. Furthermore, established workflows require flexible techniques which can adapt when changes in research are called for.
Given these challenges, versatile library fabrication routes and instrumentation that can be easily modified and applied to a variety of applications are extremely valuable to polymer researchers.
Thus, the development of gradient library fabrication approaches by the Polymers Division of the National Institute of Standards and Technology help speed the application of advances in polymer science.
Visual: Dr. Peter Johnson on camera.
“For photopolymers it’s really the big concern is the light dose, which is light intensity times exposure time and what you can do is tailor both of those parameters and you can use any kind of combination which gives you a wide range of dose properties that you can test and that’s much easier than doing a single experiment over and over again.”
Visual: Dr. Johnson illustrates procedure he is describing.
“This is just our standard UV wand. It has a fully broad exposure area. So, we place our sample here. We’re going to have exposure time be constant in this direction while we’re going to have a varying exposure time gradient in this direction.
So, this wand is at a fixed intensity here. And, the intensity actually varies with as a function of distance squared. So, we can actually move this wand up and down. So, if we turn this we can actually get it to raise and you can actually see the light wand move up and the actual light broadens and it becomes less intense because you’ve moved the stage up.
So, we can fix the light intensity at a specific position and only change the exposure time. The motor will step in slight increments dependent on the exposure time that you are running.
So, in every single case here, it’ll step slightly and that step will take longer and longer to produce over time. You can manipulate the exposure time gradient to whatever sort of system that you want and we have this system where we can configure it to different sorts of function types.
So, we have an exponential function. So, we have the case where, say, this would be up to 60 seconds and then from 60 seconds to two minutes you have this weird sub-optimal, non-clear coating
and then you have the fully cured coating where I can just rub my finger over it and nothing happens. And, then, in the bottom here, I can actually still wipe my fingers through it because it’s still monomer. And, that’s sort of where you can see this being a powerful technique.”
Visual: Dr. Stafford on camera.
“In this case, we’re going to change the UV intensity while keeping the UV exposure time constant. And, we’re going to change the UV intensity by using a filter that filters out the UV light in a very controlled fashion.”
Visual: Dr. Johnson illustrates the procedure he is describing.
“So, in this case, we have a neutral density filter that can attenuate the UV light by an absorbent coating that formed in a gradient across this sample. And, we have step gradients. On one end we are allowing all the light intensity to transmit to the sample. On the other end, all the light intensity is being absorbed. So, you have a very clearly defined gradient of light intensity that will be exposed on this sample. And, so, in this particular demonstration we’re putting the neutral density filter in between the light source and our sample so we’re exposing the entire sample all at once so it’s highly parallel.
So, there’s our light beam. We’re exposing our sample with UV light. What we can do is choose a particular exposure time, we’re keeping that fixed, and the intensity will decay from one side of the sample to the other because of this neutral density filter.”
Visual: Dr. Johnson on camera.
“The practical reality is that once industry makes a new monomer that is fantastic, it has new properties, you have to integrate that into an existing composition. And, so, when you do that you pretty much have to run every analysis like you did before. And one of them, actually, is testing, well, does this cure the same as it did before. And that’s one of the large bottlenecks because if you have to burn a sample for, say, 10 minutes and you’re changing the composition slightly every single time, that time builds up. So, it’s mainly trying to speed up the process of discovery so that once you actually get the new chemical, how can you integrate that into what goes out to the end user faster.”
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