Cold Welding of Metal-Organic Framework

National Science Foundation (Grant No. 1068952) (PI/L. Tan; Co-PI/X. Zeng).
Cold welding of Metal-Organic Frameworks
Ziguang Chen1, Zhanping Xu, Jinyue Jiang1, Banglin Chen2, and Li Tan1* (ltan4@unl.edu)
1Department
of Mechanical and Materials Engineering, University of Nebraska, Lincoln, NE, 68588,
2Department of Chemistry, UniVersity of Texas-Pan American, Edinburg, Texas 78541.
c
b
Mof 3 CW
Without
MofCW
3c
With
B
Interlayer
In plane
C
D
c
Intensity (a.u.)
Metal Organic Frameworks (MOFs), a class of hybrid materials
that combine organic ligands with metal atoms, is thought to
have a bright future for various applications.
The weakest inter layer
Heterogeneous structure
connection : (2 0 0) planes
Specific bond energy
Metal-Organic Framworks
10.6
10.8
11.0
11.2
11.4
11.6
11.8
(1 1 -1) (2 0 0) (1 1 1) (0 0 2) (0 2 0) (0 2 2)
a
b
10
Cold welding
12
14
16
18
20
22
2θ (degree)
No any changes revealed in XRD expect the full width
at half maximum (FWHM).
A Bold Idea:
Powder Cold Welding: Micro scale
?
Reality:
Complex nanoparticle-assembly revealed on the
surface.
Surface Cold Welding: Nano scale
Objectives
Understanding the heterogeneous structure of
MOFs;
Explore the possibility of cold welding (CW);
Using cold welding to make a free-standing film;
Cu-MOF

Grain Size: From ~10 nm to ~30 nm
Young’s Modulus: From ~5 GPa to 13 GPa

Hardness: From ~400 MPa to 900 MPa
Without CW
With CW
Sequential growth in real-time.
Monolayer growth limited by buckling.
Manufacturing defects get self-repaired.
After cold welding, the powder-assembly is elastic;
The free standing film is of similar yield strength
as polycarbonate.
2
(0
0
(0
c
2)
2)
Conclusions
(0
2
0)
(2 0 0)
(0 0 2)
(1 1
-1)
b
(0 2 2)
a
(0 2 0)
100 µm
(2 0 0)
50 µm
Heterogeneous feature is revealed in MOF
crystals;
Cold welding is achieved with Cu-MOF ;
Cold welding makes application possibility
of MOFs in engineering materials .