High-Resolution and Quantitative AFM Mapping of The Mechanical - PowerPoint PPT Presentation

High-Resolution and Quantitative AFM Mapping of The Mechanical Properties of Polymers Sergei Magonov 1 , Marko Surtchev 1 , Sergey Belikov 1 , Ivan Malovichko 2 and Stas Leesment 2 1 NT-MDT Development Inc., Tempe AZ USA 2 NT-MDT, Zelenograd-Moscow, Russia

Outline 1. Studies of Local Mechanical Properties in AFM 2. Quantitative Nanomechanical (QNM) Experiments in HybriD ™ Mode 3. QNM of Neat Polymer Samples 4. QNM of Polymer Blends 5. High-Resolution QNM Mapping 6. Conclusions 2 of 23 2 of 21

Studies of Local Mechanical Properties in AFM Deflection-vs-Distance Curve AFM Modes DMT: E el =2.9 GPa PVAC Contact Mode AFM Operator & Operating Procedures O-P: E el =2.3 GPa Loading & Aligning a Probe Single probe and multi-probe cartridge; manual and automatic alignment Max. Deformation-vs-Amplitude Max. Force-vs-Amplitude Amplitude-vs-Distance Curve Loading of a Sample Oscillatory Resonance Mode: LDPE E, GPa Amplitude Modulation Manual and automatic loading E, GPa Engagement of a Probe Manual and automatic engagement; soft approach algorithm Deflection-vs-time Curve Deflection-vs-Distance Curve Oscillatory Non-Resonance Mode: Hybrid Mode Measurements’ Routines Currently HybriD Mode is most optimal for Quantitative Studies at variable tip-forces; Nanomechanical Studies and automated and non-attended High-Resolution Mapping of multi-site and multi-probe Elastic Modulus and Adhesion experiments 3 of 21

Studies of Local Mechanical Properties in AFM Comparison of Tip-Sample Forces in Different AFM Modes HybriD Mode Amplitude Modulation Mode Contact Mode Height Height Phase Dodecanol Adsorbate on MoS 2 90 nm 7 nm 200 nm All three modes complement each other in the nanoscale characterization of materials. The contact mode is most suitable for lateral force imaging and piezoresponse studies. The amplitude modulation is superior for operation at low forces and for multi- frequency approaches in studies of local electric properties. 4 of 21

Quantitative Nanomechanical Study in HybriD Mode On-Line and Off-Line Analysis of Force-versus-Time or Force-versus-Deformation Cures Fit of the Force-vs- Time “Inverted Parabola” Curve Point-by-Point Calculation of Elastic Modulus and or Part of It to Find Average Elastic Modulus and Work of Adhesion from Region of Interest of Force- Work of Adhesion (I. Malovichko, NT-MDT) versus-Deformation Curve (S. Belikov, NT-MDT) Elastic modulus and Work of Adhesion Maps are collected as the arrays up to 1024×1024 size. On-line and off-line analysis can be performed using Hertz, DMT and JKR models. 5 of 21

QNM Study in HybriD Mode: Experimental Details Finding of Probe Spring Constant and Optical Sensitivity Samples: 1. Neat polymers in blocks: Polycarbonate ( PC ), Low-density polyethylene ( LDPE ), octene- branched polyethylene with density 0.87 g/cm 3 ( PE87 ) 2. Polymer blends as films with thickness above 100 nm: Polystyrene-PS with LDPE ( PS|LDPE ), PS with poly(methyl methacrylate) ( PS/PMMA ), PS with high-density polyethylene ( PS|HDPE ), PS with poly(butadiene) (PS/PBd ), PS with poly(vinyl acetate) ( PS/PVAC ), syndiotactic PS with poly(vinyledene fluoride) ( sPS/PVDF ) Inverse optical sensitivity (IOS) can be obtained from Dvt & DvZ curves in the 3. Films of block copolymers ( PS-b-PMMA , PS-b- HybriD and contact modes. PBd-b-PS ) and blocks of semicrystalline HDPE Error Propagation in QNM Analysis of Force Curves and linear low-density polyethylene ( LLDPE )   3 2 4 4 a a  Experimental:       3 / 2 Hertz: DMT: P h E R h 2 wR P kD E , h r 3 3 R R Si probes with stiffness of k = 25 N/m and 28 x x = DvZ; y = Dvh N/m and a nominal tip radius of 10 nm were  1 dD 1 dD 2 a y   E 1      x applied. r dh dD / dZ 1 dh k Force range was in the 5 nN - 100 nN range 2 aE 1  2   1  r x y x Scan rate was in the 0.4 - 1.0 Hz range   aE k x r Oscillation amplitude: 20 nm at 1. 5 kHz; Table 1. Probes with Minimal k (N/m) for Material with Modulus E (Pa) & Error Propagation of 2 for soft samples - up to 100 nm at 1.5 kHz. E, Pa 10M 50M 0.1G 0.5G 1G 3G 5G 10G 20G 30G 40G Typical Map density 512 x 512 k, N/m 710m 2.1 3.3 9.6 15.2 31.6 44.5 70.5 111.7 146.6 177.6 Saving Force Curve (Force Volume) - optional 6 of 21

T hermal, A coustic, V ibration E nclosure • Temperature stability better than 0.01C 0.005 ˚ C • Thermal drift lower than 0.2 nm/min Silver Nanoparticles on Mica: Scans (512×512) with 1 Hz rate 7 of 21

QNM of Neat Polymers: Polycarbonate Block Height Elastic Modulus Fvt FvZ 60 nN 60 nN 60 nN 30 nN 20 nN 1 m m 1 m m Deformation Work of Adhesion Elastic modulus 60 nN 60 nN 20 nN 30 nN 30 nN Deformation 20 nN 1 m m 1 m m 60 nN 30 nN 20 nN 8 of 21

QNM of Neat Polymers: Low-Density PE Block Height Elastic Modulus Fvt FvZ 60 nN 60 nN 60 nN 30 nN 20 nN 1 m m 1 m m Deformation Work of Adhesion Elastic modulus 60 nN 60 nN 30 nN 20 nN 30 nN Deformation 20 nN 60 nN 1 m m 1 m m 20 nN 30 nN 9 of 21

QNM of Neat Polymers: Octene-PE 0.87 Block Height Elastic Modulus Fvt FvZ 60 nN 60 nN 60 nN 30 nN 20 nN 1 m m 1 m m Elastic Modulus Deformation Work of Adhesion 60 nN 20 nN 30 nN 60 nN 30 nN Deformation 20 nN 1 m m 1 m m 60 nN 30 nN 20 nN 10 of 21

QNM of Polymer Blends: PS/PBd Phase Height Height Elastic Modulus 6 nN 1.5 m m 1.5 m m 5 m m 1.5 m m Elastic Modulus, 6 nN Height Elastic Modulus 20 nN Elastic Modulus, 20 nN 1.5 m m 1.5 m m 11 of 21

QNM of Polymer Blends: PS/LDPE Elastic Modulus Height Elastic Modulus Deformation Deformation 5 m m 5 m m 5 m m Elastic Modulus Height Elastic Modulus Deformation Deformation 2 m m 2 m m 2 m m 12 of 21

QNM of Polymer Blends: PS/HDPE Height Elastic Modulus Phase Height 7 m m 7 m m 7 m m 7 m m Elastic Modulus Height Elastic Modulus Deformation Deformation 2 m m 2 m m 2 m m 13 of 21

QNM of Polymer Blends: PS/PMMA Map of PMMA Raman Band Height Height Elastic Modulus 30 nN 2 m m 20 m m 20 m m 2 m m Elastic Modulus Height Elastic Modulus 80 nN Elastic Modulus 2 m m 2 m m 14 of 21

QNM of Polymer Blends: PS/PVAC Height Elastic Modulus Elastic Modulus 7 m m 7 m m Height Height Elastic Modulus Elastic Modulus 2 m m 2 m m 2 m m 15 of 21

QNM of Polymer Blends: sPS/PVDF Height Work of Adhesion Elastic Modulus 6 m m 6 m m Elastic Modulus Deformation Deformation 6 m m 6 m m 16 of 21

High-Resolution QNM of Polymers: HDPE Height Height Height 1 m m 3 m m 1 m m Elastic Modulus Work of Adhesion Height Elastic Modulus 400 nm 400 nm 400 nm 17 of 21

High-Resolution QNM of Polymers: LLDPE Height Height Phase 1 m m 3 m m 1 m m Elastic Modulus Height Elastic Modulus 1 m m 1 m m 18 of 21

High-Resolution QNM of Polymers: PS-b-PB-b-PS Height Elastic Modulus Height Work of Adhesion 1 m m 400 nm 400 nm 400 nm Height Deformation Elastic Modulus Elastic Modulus 150 nm 150 nm 150 nm 19 of 21

High-Resolution QNM of Polymers: PS-b-PMMA 6 nN Elastic Modulus 25 nN Height Elastic Modulus Height 1 m m 1 m m 1 m m 1 m m Elastic Modulus Height Elastic Modulus Elastic Modulus 400 nm 400 nm 400 nm 20 of 21

Conclusions QNM measurements of polymer samples in HybriD mode verified the value of quantitative mapping of elastic modulus for characterization of polymers and, particularly, for compositional mapping of heterogeneous materials. High spatial resolution of modulus mapping approaching 10 nm was demonstrated on lamellar structures of semicrystalline polymers and block copolymers. These results provide a solid background for studies of mechanical properties of polymers at interfaces and in other confined geometries. A combination with local electric and spectroscopic methods will make such studies even more comprehensive. In our next HybriD mode applications we will address the viscoelastic behavior of polymers. 21 of 21