Science Tuesday: shape memory polymers ← FREE KRAUT!

Science Tuesday: shape memory polymers 77

Some materials exhibit a phenomenon known as “shape memory.”  Shape memory is exactly what it sounds like: a material that has a native shape that it remembers even upon deformation.  The neat thing is that you can “freeze” the material into a deformed shape, any shape you please, and then upon gentle heating the original shape is restored.  You can cycle the material through many of these freeze/thaw cycles, each time choosing a different shape if you please, and so long as you have engineered the material correctly it will always go back to its original shape.

Shape memory was first seen in metal alloys such as nickel-titanium.

Metals are great, but the real cool shape memory materials are polymers, or plastics, since they can recover their original shape after much more aggressive deformation and can be programmed to undergo some truly gnarly shape changes.  Here’s one group that did a little bit of P.R. in their movie:

How does it work? Shape memory polymers consist of two components. The first is a soft, deformable polymer. The second component is a polymer that crystallizes when the temperature is lowered appropriately. When you first cast the material, it the material forms “network points” on the nanoscale. When you increase the temperature, the network points break in a process analogous to melting. At this point, you can deform the material, in some cases over 200%, and – while holding it in its deformed shape – bring the temperature back down. The crystallizable component undergoes the opposite process as it did when you raised the temperature – that is, it “freezes” – and the material is locked into its deformed shape. When you increase the temperature above the “melting” temperature, the material begins to deform and naturally works to re-form its original network points, thereby recovering its original shape.

With some clever engineering, you can embed multiple programmed shapes into the material.

You can imagine a number of pretty cool applications for shape memory polymers. One of the first was for “smart sutures,” which are basically knots that tie themselves when actuated by a little bit of heat. If the actuation temperature is somewhere between room temperature and body temperature, you can imagine a surgeon placing a loose suture into the body and letting it tie itself. At the bottom of this page there are a few quicktime movies. The second one is a self-tying suture. Other groups have made devices that you can roll into a tube, insert into an blood vessel, and have it unfold itself into a stent in order to support weakened blood vessels. Groups are currently working to create shape memory polymers that respond to stimuli other than heat (like light or moisture, for example), create smaller devices, and decrease (or control) the reaction time.

Any baseball applications you can think of?

77 thoughts on “Science Tuesday: shape memory polymers

  1. mk Aug 25,2009 7:53 am

    I have stupid questions, you have smart answers:

    What happens if part of the plastic is broken while in the deformity phase? Will it partially reconstitute (“working around” or disregarding the broken bit), or does the break muck up the whole process? For example, in the second video, if you tore a big chunk out of the flat portion, would the coat hanger hooks still form properly?

    When you first cast the material, it forms “network points” on the nanoscale.

    What exactly do you mean by “cast the material”? I guess this is a way of telling a hunk of plastic, “this is your shape”. But how does that work?

    With respect to the network points: OK, you have a shape with network points, which reconnect at the end of this deform/reform process. Can you create a new set of “original network points” for the same hunk of plastic? Can you say “your true shape was a coat hanger, but now your true shape is a popcorn bowl”? (if I was a scientist, I would definitely talk to the polymers) Do you just have to melt it down (or whatever), re-“cast” it, and voila, new shape, new network points?

    Also: can you deform/reform, deform/reform an unlimited number of times (i.e. tie/untie the suture), or will the process eventually break down?

    • salb918 Aug 25,2009 8:15 am || Up

      A lot of these answers are going to be educated guesses, since I’m far from an expert…

      1. In areas that have been traumatized by the break, the whole process is going to get mucked up. But far from the break, the network points, and therefore the programmed memory, will be undisturbed and will behave normally. The question is how far is far. That distance is probably governed by the length of the polymer chains (a polymer is a chain of carbon atoms, not unlike molecular spaghetti) as well as the density of network points. My guess is that from any given break, you would have to travel several hundred nanometers, maybe up to a micron (about a fiftieth of the thickness of a human hair).

      2. Casting the material can be as simple as blending a few precursor materials together into a mold and curing it (with heat or UV light, for example).

      3. Not sure about this one. Many shape memory polymers are copolymers, meaning that they contain two distinct chemical identities in the molecular spaghetti. (Think of it this way: a homopolymer is a chain of consisting of repeat units of A, so its structure is AAAAAAAAA… A copolymer has some B in it as well, so you have AAABABABBAAAB…) In those cases, I would guess that you cannot reprogram its true shape from coat hanger to popcorn bowl.

      In other cases, the shape memory polymers are actually physical blends, meaning that you mixed AAAAAAAAAAA… with BBBBBBBBBBBB… in a beaker. My intuition is that in those cases you can dissolve the polymer in an appropriate solvent and recast it. Again those are just guesses.

      4. In a well-designed shape memory system, you should be able to do the deform/reform cycles hundreds of times without damaging your system.

      • mk Aug 25,2009 9:35 am || Up

        4. Can you program it to deform to the same shape every time? In other words, can you go from Shape A (original) to Shape B (preferred deformity) to Shape A to Shape B ad infinitum, or is it Shape A to Shape X (where X is variable/uncontrollable)? You can probably only have one “saved structure” (set of reconstitutable network points) at a time, right? So the deformity just ends up however it ends up?

        • salb918 Aug 25,2009 12:05 pm || Up

          I am not sure. I *think* that it is currently only A–>X (where X is variable). But, I imagine that you could to A–>B if you engineered things correctly.

          There are A–>B–>A systems for flat surfaces, so that you can make a water either spread or bead up on a surface based on whether you apply a voltage to the surface.

    • monkeyball Aug 25,2009 8:24 am || Up

      What if you tire before it’s done?

      you better hope to God you don't show up in this little community, because you'll wish you had never come
      • the dogfather Aug 25,2009 5:15 pm || Up

        Then it’s called Saturday evening at the SeeLaBees’.

        The meaning of life is not so much found, as it is Made. -- Opus
  2. monkeyball Aug 25,2009 8:25 am

    See? Now anyone who charges $35K/y+ for this is engaging in extortion.

    you better hope to God you don't show up in this little community, because you'll wish you had never come
    • salb918 Aug 25,2009 8:27 am || Up

      Says the history major.

    • mk Aug 25,2009 9:37 am || Up

      I don’t understand this recurring higher education extortion theme. I guess I’m not reading Free Kraut closely enough these days.

      • nevermoor Aug 25,2009 10:05 am || Up

        FK isn’t what you aren’t reading closely enough.

        "There's never enough time to do all the nothing you want"
        • andeux Aug 25,2009 10:16 am || Up

          Ah. The “extortion” part is an overstatement, but there’s a lot of truth in this:

          The economic function of college is not to actually improve your value, but rather to provide an expensive screening process whereby some individuals can be chosen above others.

          TINSTAAFK
          • nevermoor Aug 25,2009 10:42 am || Up

            Not my experience. If a college doesn’t improve your value, they don’t get alumni contributions from you, which means a lot more than four years of tuition.

            "There's never enough time to do all the nothing you want"
            • andeux Aug 25,2009 11:23 am || Up

              The “screening process” is what improves your value. Hey, I’m not complaining, I went to the best signifier in the country. (And, for the record, I learned a lot in both college in graduate school. But much of what I learned was not particularly useful for any practical purposes, and the parts that were I could probably have picked up just as quickly and considerably less expensively elsewhere, as iglew suggests.)

              TINSTAAFK
              • nevermoor Aug 25,2009 11:34 am || Up

                I’m still not convinced. I fully agree that parts of my education were not useful (I find few occasions to apply my research on 11 century popes or on simulating city traffic patterns), however I do think I emerged better at learning/thinking in general.

                Could I have done that on my own? Maybe, but I wouldn’t have.

                "There's never enough time to do all the nothing you want"
                • salb918 Aug 25,2009 11:55 am || Up

                  One of the things I realized in grad school was that I learned more from my peers than from my instructors. This is equally true for both “life lessons” as well as complex, specialized technical problems.

                  If your definition of higher learning is limited to watching online lectures and reading textbooks, UR DOIN IT RONG.

                • nevermoor Aug 25,2009 3:32 pm || Up

                  This. Although I do take mk’s point on our bias seriously.

                  "There's never enough time to do all the nothing you want"
                • mk Aug 25,2009 4:37 pm || Up

                  I think there are probably better places to learn life lessons than grad school, no? (or if not better, different at least, and less expensive)

                  With respect to critical thinking cultivation (or whatever you want to call it), I would guess that people with nice degrees tend to inflate the utility of their time in school, while those of us without them probably over-disparage the process.

                • nevermoor Aug 25,2009 4:47 pm || Up

                  Depends upon the life lessons I suppose. In sal’s case, there probably isn’t a better place to have the collaborative-science life experience. I know I learned a lot of life lessons (defined, I assume, as non-book-learning) in college. Less so in Law School.

                  I would guess that people with nice degrees tend to inflate the utility of their time in school, while those of us without them probably over-disparage the process.

                  I think this is probably right. Maybe in part because I wouldn’t be where I am without mine, and you’d be no better (I assume, based on your comments) with one.

                  "There's never enough time to do all the nothing you want"
                • salb918 Aug 25,2009 6:05 pm || Up

                  So those who get useful educations think it’s worth it and those who got useless educations didn’t? That seems to go without saying!

                • mk Aug 25,2009 6:26 pm || Up

                  That does go without saying! Alas, it’s not what I said.

                  To re-phrase:

                  If you have a degree from a good university, you might be inclined to overestimate the value of those years to some extent (in the “it taught me how to think” sense, not in the career/income sense, where it’s worth is concrete, obvious, and quantifiable). Since I’m on a Pulp Fiction quote run this week: that’s pride fucking with you. If you do not have such a degree, you may be inclined to regard it as a bunch of snooty hooey that you could just as easily learn on your own (that would be envy and regret fucking with you).

                • salb918 Aug 25,2009 6:27 pm || Up

                  ok, got it now. Thanks for the clarification.

                • andeux Aug 26,2009 10:10 am || Up

                  I guess all that fancy book-learning didn’t help you with your reading comprehension.

                  TINSTAAFK
                • salb918 Aug 25,2009 6:31 pm || Up

                  Well, I didn’t *pay* to go to grad school.

                  What I was getting at was this: a lot of people think the “learning from your peers” aspect is all about life lessons and diversity of thought/experience.

                  In my experience, I found that I actually learned a lot about complex, specialized, technical issues from my peers. Moreso from them than my instructors, textbooks, independent review of relevant literature, etc.

                • mk Aug 26,2009 8:01 am || Up

                  That makes sense. I should have read your comment more carefully.

                • andeux Aug 26,2009 10:11 am || Up

                  Maybe if you had finished college your reading comprehension would be better.

                  TINSTAAFK
                • mikeA Aug 25,2009 3:59 pm || Up

                  Same here. College improved my thinking a lot, and it’s not clear that that would have happened otherwise.

        • salb918 Aug 25,2009 10:30 am || Up

          Thanks, I was wondering that myself.

          • nevermoor Aug 25,2009 10:43 am || Up

            It’s actually the best thread there’s been on ** in quite awhile (in totally unrelated news, the chief administrator has made about two comments in it)

            "There's never enough time to do all the nothing you want"
            • nevermoor Aug 25,2009 10:44 am || Up

              Also, it’s what I was referencing in my “DFA should be an ** author” comment

              "There's never enough time to do all the nothing you want"
              • mk Aug 25,2009 11:19 am || Up

                Thought experiment:

                Let’s say Person X (“James Smith”) posts on AN all the time. And in the course of those postings, James Smith makes all manner of disparaging comments about you and monkeyball in your capacities as quasi/de facto administrators of FK. James Smith nudges all his AN friends, saying “look at the knucklehead monkeyball, see this email he sent me, ha ha, what a dork, so clueless.” Fine so far, right? It is, after all, a time-honored blog tradition to mock other blogs, and as far as that goes, all of us here are in glass houses, that’s for sure.

                But then, wouldn’t it be weird if James Smith also continued to comment regularly at FK? Wouldn’t you be disposed to regard James Smith as kind of a dick?

                I don’t know, maybe it’s not weird or dickish. But I don’t think I would do it.

        • mk Aug 25,2009 11:57 am || Up

          Wow. I can’t imagine ever devoting more than a line or two of snark to mocking Urban, but A for effort.

          mikeA in the comments:

          Graduating college indicates that those who do have at least minimal levels of intelligence and diligence, which is valuable information for employers (who are not awash in valuable information.) Lots of people paying a bunch of money for college is perhaps an inefficient means of accomplishing that, but it’s something…

          Yes, it’s something. It’s a lazy shortcut that results in the hiring of lots of incompetent people with high self-regard, and more importantly, the exclusion of many capable, hard working people who lack higher education bona-fides.

          Setting aside professions where the baseline skill set is almost exclusively acquired via college (engineering, lawyering, and so forth), in the Generic Cubicle Workforce (that of Business Analysts, Project Managers, etc.), a degree on a resume tells you precisely nothing. With respect to “valuable information”, unless you are hiring someone straight out of school, if you are not looking at work experience first, second, third, … ninth, and tenth, you are making a mistake. Maybe the degree would be eleventh, in case of a tie.

          I get the sense, as well, that many in that thread (and here) attended really good schools (Stanford, etc.) that probably do teach you a thing or three, and invariably spit graduates into higher-end professions (lawyer, etc.). I propose that this cultivates a skewed perspective. Most people go to shitty (but still relatively expensive) mid/lower-tier colleges, basically for the reasons enumerated by iglew, and, “incentive structures” or no, emerge with roughly the same capacity for analytical thinking and problem solving they went in with. This is because the classes suck, and are appallingly easy to pass. So when you see a business/communications degree from George Mason University or wherever on a resume, you can safely assume it is, for all intents and purposes, bullshit.

          • oblique Aug 25,2009 12:07 pm || Up

            IME, identifying non-technical people who are bright, motivated and resourceful, and know how to cut through some bullshit and deal with the rest, is extraordinarily difficult. And I completely agree with you that in those fields, the college degree means nothing to me — I don’t even look at it.

            For the technical fields, my argument (before I saw the “Setting aside…” clause) was going to be that getting a college degree is a measure of how motivated someone is to complete a (possibly contrived) goal despite a lot of bullshit — which can be a useful skill in many work environments.

            Interestingly, the inverse skill (not being willing to put up with the bullshit) can be even more useful in other environments.

            • mk Aug 25,2009 1:29 pm || Up

              Agreed all around.

              I might restate “not being willing to put up with the bullshit” as “the capacity to a) recognize bullshit as bullshit, and b) disentangle the important stuff from the bullshit, in order to focus on said important stuff, while simultaneously pretending that you regard the bullshit as important, so as not to alienate yourself from the majority of your co-workers (and probably your boss), who believe fervently in the bullshit and use phrases like ‘vertical integration’ unironically.”

              • oblique Aug 25,2009 1:50 pm || Up

                Wow, nice. I guess that shows why I’m not one of those people! :-)

          • FreeSeatUpgrade Aug 25,2009 1:39 pm || Up

            As a non-degree holding non-tech professional who’s achieved a fair level of success, that’s certainly how it played out for me. The life-proved achievements are way more dependable to employers than the sheepskin is. But for many businesses screening apps with degree = pass/fail is the easy way out regardless.

            And amusingly, George Mason is actually the go-to safety school for kids from my high school, which I never once considered after dropping out of several much more formidable institutions.

            "Kraut will get you through times of no money better than money will get you through times of no kraut."
            • mk Aug 25,2009 2:16 pm || Up

              I flunked out of GMU twice. Make of that what you will, in light of my comments above.

          • nevermoor Aug 25,2009 3:31 pm || Up

            I get the sense, as well, that many in that thread (and here) attended really good schools (Stanford, etc.) that probably do teach you a thing or three, and invariably spit graduates into higher-end professions (lawyer, etc.).

            Good point, and guilty as charged re: bias.

            And I do hear you on tuition getting out of step (one of my best HS friends is still pissed off by how much more BU tuition was than mine).

            I guess my desire is to say that my experience was valuable so therefore college must be valuable, but I certainly couldn’t tell you that all colleges are like mine. I do think that focusing on the major is significant, however, since even at less well regarded schools you can still get a great education. It’s just that you don’t have to in order to graduate.

            "There's never enough time to do all the nothing you want"
            • mikeA Aug 25,2009 3:49 pm || Up

              You went to Bullshit University?

              • nevermoor Aug 25,2009 4:01 pm || Up

                No. He did. (and they’re exorbitantly expensive, which was fine since he was ROTC)

                "There's never enough time to do all the nothing you want"
          • mikeA Aug 25,2009 3:54 pm || Up

            Certainly having/not having a degree or what kind of degree it is quickly recedes in relevance once people have job experience, but part of the point is to be able to get in the door in the door to some sort of semi-good job in the first place.

            • mk Aug 25,2009 3:58 pm || Up

              I agree –> “unless you are hiring someone straight out of school”

    • nevermoor Aug 25,2009 10:05 am || Up

      Depends upon whether they give you materials to do it yourself. Plus, if those kids didn’t go to MIT, how would they have branded their video?

      "There's never enough time to do all the nothing you want"
  3. monkeyball Aug 25,2009 8:28 am

    How about a synthetic infield dirt (turf stadia already use synthetics for the warning track) that when wet transforms into a tarp that covers the entire infield? (I’m guessing that the entire substance needs to remain whole/intact, rather than aggregate like “dirt.”)

    you better hope to God you don't show up in this little community, because you'll wish you had never come
    • salb918 Aug 25,2009 11:09 am || Up

      Like the concept, but your parenthetical guess is the likely bugaboo.

      • monkeyball Aug 25,2009 3:27 pm || Up

        There’s also the fact that if the transformation is rapid/simultaneous enough, a sudden downpour could result in a decapitated infielder or 4.

        you better hope to God you don't show up in this little community, because you'll wish you had never come
        • dmoas Aug 25,2009 11:59 pm || Up

          I think I might sit and hope for rain for that. Can Crosby be one of the fielders?

    • green star oakland Aug 25,2009 2:25 pm || Up

      Nanoturf on top of a controlled heating/cooling layer – turn the blades into little springs for funky hops when the A’s are batting.

      If this is His will, He's a son of a bitch.
  4. monkeyball Aug 25,2009 8:31 am

    Dammit. Home today with JP (little case of roseola), but antiquated history-major-salary Mac doesn’t like embedded Flash video.

    you better hope to God you don't show up in this little community, because you'll wish you had never come
  5. salb918 Aug 25,2009 11:11 am

    That story about the wave sweeping the girl off the rocks at Acadia really shook me up. We were there almost exactly 24 hours earlier, and judging by the video, walking around the same area. Granted it was low tide the day before the hurricane, but still. My son was climbing rocks right there.

  6. nevermoor Aug 25,2009 11:18 am
    "There's never enough time to do all the nothing you want"
  7. FreeSeatUpgrade Aug 25,2009 1:40 pm

    I’m counting on these fancy new polymers to provide me with better plastic lawn furniture in the face of the ever-more-virulent assault from the sun.

    "Kraut will get you through times of no money better than money will get you through times of no kraut."
  8. lenscrafters Aug 25,2009 2:34 pm

    Bobby Crosby’s dad is pretty pissed off.

    “He’s a shortstop, and a darned good one if they would just leave him alone.”

    *sigh*

    • batgirl Aug 25,2009 2:57 pm || Up

      The elder Crosby says there’s no chance his son will re-sign with Oakland

      I chuckled.

      • monkeyball Aug 25,2009 3:28 pm || Up

        Father of the year

        you better hope to God you don't show up in this little community, because you'll wish you had never come
        • nevermoor Aug 25,2009 3:35 pm || Up

          Bobby’s not hurt, period.

          Has that ever been true?

          "There's never enough time to do all the nothing you want"
          • mk Aug 25,2009 3:54 pm || Up

            If it is true, and they’re stashing him on the DL in order to avoid cutting Nomar, that’s … bizarre.

            • nevermoor Aug 25,2009 4:02 pm || Up

              Should just cut both of ’em

              "There's never enough time to do all the nothing you want"
              • mk Aug 25,2009 4:53 pm || Up

                Maybe Nomar is setting an awesome example for the youngsters or something. It could be that he sits in the dugout during games exuding such a potent mix of grit and wisdom that anyone who walks by magically gets dirt on their pant leg and starts talking sagely about what he needs to do to cover the outside corner. Pennington has probably already absorbed all sorts of insight about how to be a steely-eyed leader. By the time Kennedy, Ellis, and Nomar are through with him, he’ll be approaching Jeter levels of elite playthegametherightwayness.

    • andeux Aug 25,2009 3:47 pm || Up

      They take all the aggressiveness out of their players. Look how much better guys like Eric Burns [sic] and Nick Swisher and Marco Scutaro have become once they got out of Oakland.

      Byrnes had his best year in Oakland.
      Swisher had his best year in Oakland.
      Scuatro is having a career year, in large part because he is walking more.

      TINSTAAFK
      • oblique Aug 25,2009 4:47 pm || Up

        + a fucking zillion.

      • monkeyball Aug 25,2009 5:48 pm || Up

        Fixed.

        They take all the aggressiveness value out of their players. Look how much better paid guys like Eric Burns [sic] and Nick Swisher and Marco Scutaro have become once they got out of Oakland.

        you better hope to God you don't show up in this little community, because you'll wish you had never come
    • mikeA Aug 25,2009 3:56 pm || Up

      I agree with Mr. Crosby. Give him a bus ticket or something and don’t call him anymore. Maybe we’ll see him playing SS in a corn field in Iowa…

    • oblique Aug 25,2009 4:49 pm || Up

      “He is white and good looking, and should therefore be given several more chances.”

    • monkeyball Aug 25,2009 5:54 pm || Up

      Awesome:

      “I love the way Mike Scioscia has the Angels playing. They’re so aggressive both with their bats and with their baserunning. They’re always attacking. That’s not the case with the A’s.”

      PleasesignwiththeSlegna PleasesignwiththeSlegna PleasesignwiththeSlegna PleasesignwiththeSlegna PleasesignwiththeSlegna PleasesignwiththeSlegna

      you better hope to God you don't show up in this little community, because you'll wish you had never come
    • oblique Aug 25,2009 6:10 pm || Up

      Hey, guess what?

      Ed Crosby sucked too!

      Career OPS .547
      Career OBP .282

      Then again I’m too stupid to decipher the fielding stats, so maybe he was a stud on defense AS A UTILITY INFIELDER.

  9. lenscrafters Aug 25,2009 4:30 pm

    Did anyone check out McCoveyChronicles after last night’s debacle? They were on par with Lookout Landing-esque despair/hilarity. There was a random Darth Maul/Bothans/Justin Miller is a Bothan reference in there that made me laugh.

    • nevermoor Aug 25,2009 4:54 pm || Up

      Awesome.

      Although to be fair to GL, that’s basically every action movie. See, most egregiously, Enemy at the Gates (bad guy sniper never misses until he sees hero, then can’t hit anything at all ever)

      "There's never enough time to do all the nothing you want"
  10. nevermoor Aug 25,2009 5:15 pm

    This. It’s smart, and a bit snarky. Needless to say I love it.

    "There's never enough time to do all the nothing you want"
  11. nevermoor Aug 25,2009 5:35 pm

    Bobby Crosby is absolutely evil. DFA-ing him would be absolutely good.

    "There's never enough time to do all the nothing you want"
  12. oblique Aug 25,2009 6:15 pm
    Is this now a DLD?

    Because I feel compelled to link to the paintings of President Obama naked with Mark Ellis.

    Maybe there’s a use for shape memory polymers in the field of contraception?

    • salb918 Aug 25,2009 6:21 pm || Up

      “smart” polymers, though not of the shape memory variety, are used in contraceptives (not sure if these are on the market yet or not): the contraceptive drug is embedded in a polymer matrix. At vaginal pH, the matrix tightly binds the drug. At higher pH, the polymer matrix swells and releases the contraceptive. Since semen has a higher pH than the vagina, the release of contraceptive drug is actuated at just the right moment.

      • mk Aug 25,2009 6:47 pm || Up

        This doesn’t have anything to do with polymers or contraceptives, but it’s in the ballpark, and it’s making me laugh, so close enough:

        I listened to a mini-lecture yesterday that touched on Kinsey’s (often highly idiosyncratic) experiments. I guess in those days there was a theory making the rounds that the likelihood of a woman becoming pregnant was increased if the semen slammed into her cervix at a particularly high velocity.

        Anyway, intrepid researcher that he was, Kinsey decided to measure ejaculation distance, and recorded hundreds of subjects doing just that. I can’t remember the average, but the record was eight feet.

  13. salb918 Aug 25,2009 6:22 pm
    • FreeSeatUpgrade Aug 25,2009 10:41 pm || Up

      It is, and what’s more, that’s John Henry getting robbed.

      "Kraut will get you through times of no money better than money will get you through times of no kraut."

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