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From stronger Kevlar to better biology

Mon, 07/14/2014 - 9:17am
Angela Herring, Northeastern Univ.

Assistant professor Marilyn Minus has received a grant to expand her nanomaterial templating process to design better synthetic collagen fibers and better flame-retardant coatings. Image: Mary Knox MerrillPlace two large, sturdy logs in a streambed, and they will help guide the water in a par­tic­ular direc­tion. But imagine if the water started mim­ic­king the rigidity of the logs in addi­tion to flowing along them. That’s essen­tially what hap­pens in a directed assembly method devel­oped by Mar­ilyn Minus, an assis­tant pro­fessor in Northeastern’s Depart­ment of Mechan­ical and Indus­trial Engi­neering.

Instead of logs, Minus uses tiny carbon nan­otubes and her “water” can be just about any kind of polymer solu­tion. So far, she’s used the approach to develop a polymer com­posite mate­rial that is stronger than Kevlar yet much less expen­sive and lighter weight. In that case, the polymer not only fol­lows the direc­tion of the nan­otube logs but also mimics their uniquely strong properties.

With funding from a new CAREER award from the National Sci­ence Foun­da­tion, Minus is now expanding this work to incor­po­rate more polymer classes: flame retar­dant mate­rials and bio­log­ical molecules.

“With the flame retar­dants, we want the high-​​temperature polymer and nan­otube to interact, not nec­es­sarily act like the nan­otubes,” Minus said. Essen­tially, she wants the two mate­rials to “com­mu­ni­cate” by passing heat between one another, thereby increasing the tem­per­a­ture threshold of the flame retar­dants and allowing them to last even longer. “The nano­ma­te­rial can grab that heat and con­duct it away, and it basi­cally saves that polymer from burning up too quickly,” she explained. “The polymer we’re using can already with­stand quite high tem­per­a­tures; we’re just pushing it even further.”

In the case of collagen—the first bio­log­ical mol­e­cule to which Minus has applied her method—Minus hopes the approach will allow the nan­otubes to lend their rigidity to the system. Inside the body, col­lagen mol­e­cules orga­nize them­selves into a com­plex matrix that sup­ports the struc­ture of every one of our cells. But out­side the body, researchers have had major chal­lenges trying to reli­ably recreate this matrix.

If sci­en­tists could make col­lagen work out­side the body the same way it does inside, it could pro­vide an invalu­able plat­form for testing drugs, under­standing how tis­sues work, and even shed­ding light on the ori­gins of a variety of dis­eases, Minus said.

Based on her prior research, she has found that the key to suc­cess in taking this approach is matching the size and geom­etry of the carbon nanopar­ti­cles she uses with that of the polymer in ques­tion. For instance, col­lagen mol­e­cules are about 300 nanome­ters long and 1.5 nanome­ters in diam­eter, so she’ll want to find a nan­otube that roughly meets those dimen­sions. She’ll also want to use nan­otubes for this appli­ca­tion rather than the other carbon forms she has at her dis­posal: graphene, graphite, fullerenes, or even small nanocarbon particles—each of which offers a unique structure.

“We’re trying to change the entropy of the system in order to get the poly­mers to orga­nize them­selves around the nano­ma­te­rials,” Minus said. “Then you should be able to get this effect.”

Source: Northeastern Univ.

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