Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Weak hydrogen bonds key to strong, tough infrastructure

30.01.2018

Rice University lab simulates polymer-cement composites to find strongest, toughest materials

The right mix of hydrogen bonds in polymer and cement composites is critical to making strong, tough and ductile infrastructure material, according to Rice University scientists who want to mimic the mechanics of mother-of-pearl and similar natural composites with synthetic materials.


Rice University scientists probing the interfacial interactions of polymer (blue) and cement (yellow) discovered the right mix of hydrogen bonds is critical to making strong, tough and ductile composite materials for infrastructure. Computer simulations like that in the illustration measured the strength of the bonds as hard cement slides past the soft polymer in a layered composite, which mimics the structure nacre, seen in the background.

Credit: Probhas Hundi/Multiscale Materials Laboratory

Usage Restrictions: For news reporting purposes only

Seashells made of mother-of-pearl, aka nacre, get their remarkable properties from overlapping micron-sized, mineralized plates held together by a soft matrix. This structure can be approached by cement and polymer composites that may, for instance, make better earthquake-resistant concrete, according to Rouzbeh Shahsavari, an assistant professor of civil and environmental engineering.

The Rice lab ran more than 20 computer simulations of how polymers and cement molecules come together at the nanoscale and what drives their adhesion. The researchers showed that the proximity of oxygen and hydrogen atoms is the critical factor in forming a network of weak hydrogen bonds that connects soft and hard layers. Common polyacrylic acid (PAA) proved best at binding the overlapping layers of cement crystals with an optimal overlap of about 15 nanometers.

"This information is important to make the best synthetic composites," said Shahsavari, who ran the project with Rice graduate student Navid Sakhavand. "A modern engineering approach to these materials will have a large impact on society, especially as we build new and replace aging infrastructure."

The lab's results appear in Applied Physics Letters.

While engineers understand that adding polymers improves cement by blocking the damaging effects of "aggressive" ions that invade its pores, details about how the materials interact at the molecular scale have remained unknown, Shahsavari said. To find out, the researchers modeled composites with PAA as well as polyvinyl alcohol (PVA), both soft matrix materials that have been used to improve cement.

They discovered that the two different oxygen atoms in PAA (as opposed to one in PVA) allowed it to receive and donate ions as it bonded with hydrogen in the crystals of tobermorite cement. Oxygen in PAA had eight ways to bond with hydrogen (six for PVA) and could also participate in salt bridging between the polymer and cement, which makes the bonding network even more complex.

The researchers tested their simulated structures by sliding layers of polymer and cement against each other and found that complexity allowed the bonds between PAA and cement to break and reconnect more frequently as the material was stressed, which significantly increases its toughness, the ability to deform without fracturing. This allowed the researchers to determine the optimum overlap between cement crystals.

"In contrast to the common intuition that hydrogen bonds are weak, when the right number of them -- the optimum overlap -- cooperate, they provide sufficient connectivity in the composite to confer high strength and high toughness," Shahsavari said. "From an experimental standpoint, this can be done by carefully tuning and controlling the addition of the polymers with the right molecular weight while controlling cement mineral formation. Indeed, a recent experimental paper by our colleagues showed a proof of concept toward this strategy."

###

The National Science Foundation (NSF) supported the research. Supercomputing resources were supplied by Rice's NSF-supported DAVinCI supercomputer administered by the Center for Research Computing and procured in partnership with Rice's Ken Kennedy Institute for Information Technology.

Read the abstract at http://aip.scitation.org/doi/abs/10.1063/1.5017200

This news release can be found online at http://news.rice.edu/2018/01/29/weak-hydrogen-bonds-key-to-strong-tough-infrastructure/

Follow Rice News and Media Relations via Twitter @RiceUNews

Related materials:

Multiscale Materials Laboratory (Shahsavari Lab): http://rouzbeh.rice.edu/

George R. Brown School of Engineering: http://engineering.rice.edu

Rice Department of Civil and Environmental Engineering: http://www.ceve.rice.edu

Rice Department of Materials Science and NanoEngineering: https://msne.rice.edu

Located on a 300-acre forested campus in Houston, Rice University is consistently ranked among the nation's top 20 universities by U.S. News & World Report. Rice has highly respected schools of Architecture, Business, Continuing Studies, Engineering, Humanities, Music, Natural Sciences and Social Sciences and is home to the Baker Institute for Public Policy. With 3,970 undergraduates and 2,934 graduate students, Rice's undergraduate student-to-faculty ratio is just under 6-to-1. Its residential college system builds close-knit communities and lifelong friendships, just one reason why Rice is ranked No. 1 for quality of life and for lots of race/class interaction and No. 2 for happiest students by the Princeton Review. Rice is also rated as a best value among private universities by Kiplinger's Personal Finance. To read "What they're saying about Rice," go to http://tinyurl.com/RiceUniversityoverview.

Media Contact

David Ruth
david@rice.edu
713-348-6327

 @RiceUNews

http://news.rice.edu 

David Ruth | EurekAlert!

More articles from Materials Sciences:

nachricht New method inverts the self-assembly of liquid crystals
15.04.2019 | University of Luxembourg

nachricht 'Deep learning' casts wide net for novel 2D materials
11.04.2019 | Rice University

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Explosion on Jupiter-sized star 10 times more powerful than ever seen on our sun

A stellar flare 10 times more powerful than anything seen on our sun has burst from an ultracool star almost the same size as Jupiter

  • Coolest and smallest star to produce a superflare found
  • Star is a tenth of the radius of our Sun
  • Researchers led by University of Warwick could only see...

Im Focus: Quantum simulation more stable than expected

A localization phenomenon boosts the accuracy of solving quantum many-body problems with quantum computers which are otherwise challenging for conventional computers. This brings such digital quantum simulation within reach on quantum devices available today.

Quantum computers promise to solve certain computational problems exponentially faster than any classical machine. “A particularly promising application is the...

Im Focus: Largest, fastest array of microscopic 'traffic cops' for optical communications

The technology could revolutionize how information travels through data centers and artificial intelligence networks

Engineers at the University of California, Berkeley have built a new photonic switch that can control the direction of light passing through optical fibers...

Im Focus: A long-distance relationship in femtoseconds

Physicists observe how electron-hole pairs drift apart at ultrafast speed, but still remain strongly bound.

Modern electronics relies on ultrafast charge motion on ever shorter length scales. Physicists from Regensburg and Gothenburg have now succeeded in resolving a...

Im Focus: Researchers 3D print metamaterials with novel optical properties

Engineers create novel optical devices, including a moth eye-inspired omnidirectional microwave antenna

A team of engineers at Tufts University has developed a series of 3D printed metamaterials with unique microwave or optical properties that go beyond what is...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Revered mathematicians and computer scientists converge with 200 young researchers in Heidelberg!

17.04.2019 | Event News

First dust conference in the Central Asian part of the earth’s dust belt

15.04.2019 | Event News

Fraunhofer FHR at the IEEE Radar Conference 2019 in Boston, USA

09.04.2019 | Event News

 
Latest News

New automated biological-sample analysis systems to accelerate disease detection

18.04.2019 | Life Sciences

Explosion on Jupiter-sized star 10 times more powerful than ever seen on our sun

18.04.2019 | Physics and Astronomy

New eDNA technology used to quickly assess coral reefs

18.04.2019 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>