FABRICATION AND SURFACE
FUNCTIONALIZATION OF POROUS ORGANIC
FRAMEWORKS NANOMEMBRANES
Kamal Batra
Final Year Undergraduate ...
2
AIM AND OBJECTIVE
 To explore a facile method to develop porous organic frameworks
(POF’s) nanomembranes on gold coated...
WHAT ARE NANOPOROUS MATERIALS ?
 Consist of a regular inorganic or organic structure,
supporting a periodic and porous sy...
 Among the nanoporous solids 3 individual
classes can be recognized, such as
 Zeolites, crystalline alumina-silicates wi...
What are Porous Organic
Frameworks (POFs) ?
 Porous organic frameworks (POFs) are
important subclass of nanoporous
materi...
6
Schlenk Line Technique
A Schlenk line (SL) is a valuable device in synthetic organic and inorganic
chemistry, particular...
SELF-ASSEMBLED MONOLAYERS (SAMS)
 Self-assembled monolayers (SAM) of organic molecules are molecular
assemblies formed sp...
 Only since 1983 the formation of SAMs on metallic surfaces is
investigated in a systematic fashion (first study by Nuzzo...
CLICK CHEMISTRY AT ORGANIC SURFACES
 "Click Chemistry" is a term that was introduced by K. B. Sharpless in
2001 and is on...
10
Fig.7 Schematic representation of their layer-by-layer synthesis on
functionalized surfaces
For fabrication of the poro...
SPIN COATING TECHNIQUE
 Spin-coating is a process that involves depositing a
small puddle of a fluid material on to the c...
12
Detachment of Membrane from Mica Substrate
Following flow chart describes the detachment of membrane from substrate :
Sr.
No.
Chemicals Required Amount
1 Propargyl alcohol 0.00173 ml
2 Propargyl bromide 0.00266 ml
3 Propargyl ether 0.00308 ...
CHARACTERIZATIONS TECHNIQUES
 A number of different experimental methods are available for the
characterization of SAMs
(...
15
Measuring the contact angle is the simplest method to characterize
organic SAMs generated by the reaction of thiols wit...
(B) Infrared (IR) Spectroscopy
As a matter of course, investigating the wettability of organic surfaces only
with water or...
17
CHARACTERIZATION RESULTS
Contact Angle measurement of HCP on gold coated substrate before
surface functionalization wit...
18
S.No Average Contact Angles Chemical Reagents
1. 44.81o Propargyl Alcohol
2. 48.58o Ethylene Ferrocene
3. 57.82o Porpar...
S.No Average Contact Angles Chemical Reagents
1. 73.92o Ethylene Ferrocene
2. 68.18o Phenyl Acetylene
3. 55.93o Propargyl ...
CONCLUSIONS
20
In conclusion our results demonstrate the successful surface
functionalization of highly stable freestandin...
THANK YOU !!
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Porous Organic Frameworks Nano Membranes !!

FABRICATION AND SURFACE FUNCTIONALIZATION OF POROUS ORGANIC FRAMEWORKS NANOMEMBRANES
Published on: Mar 4, 2016
Published in: Education      
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Transcripts - Porous Organic Frameworks Nano Membranes !!

  • 1. FABRICATION AND SURFACE FUNCTIONALIZATION OF POROUS ORGANIC FRAMEWORKS NANOMEMBRANES Kamal Batra Final Year Undergraduate Student Department of Chemistry Indian Institute of Technology, Kharagpur Project Guide : Dr. Manuel Tsotsalas, IFG/KIT 15 May 2014 to 15 July 2014
  • 2. 2 AIM AND OBJECTIVE  To explore a facile method to develop porous organic frameworks (POF’s) nanomembranes on gold coated silicon/mica substrate.  To Investigate the surface functionalized POFs, end-capped with different chemical reagents using characterization techniques such as Drop Shape Analyser (DSA) & Infrared spectroscopy (IR)  To measure contact angle range on surfaces that can influence the hydrophobicity/hydrophilicity of nanomembranes on substrates  To explore the potential applications of POFs in functional devices such as gas storage, separation, sensing, catalysis etc.
  • 3. WHAT ARE NANOPOROUS MATERIALS ?  Consist of a regular inorganic or organic structure, supporting a periodic and porous system  Nanoporous solids as a subclass of nanomaterials.  Nanoporous materials can be subdivided into 3 categories, set out by IUPAC:  Micro porous materials: 0.2–2 nm  Meso porous materials: 2–50 nm  Macro porous materials: 50–1000 nm 3
  • 4.  Among the nanoporous solids 3 individual classes can be recognized, such as  Zeolites, crystalline alumina-silicates with framework type structures that form pores with uniform sizes of molecular dimensions by corner sharing TO4 tetrahedral (e.g. SiO4 and AlO4).  Metal Organic Frameworks (MOFs), also known as porous coordination polymers (PCPs), are crystalline compounds consisting of metal ions or clusters coordinated to often rigid organic molecules  Large Pore size for both Zeolite and MOFs come in range of 0.2 to 2 nm  Porous Organic Frameworks (POFs) ? 4 Fig.2 : Basic MOF structure Fig.1 : Basic Zeolite structure
  • 5. What are Porous Organic Frameworks (POFs) ?  Porous organic frameworks (POFs) are important subclass of nanoporous materials  They are composed of different organic moieties linked by covalent bonds, resulting in ordered and rigid structures  Exceptional thermal stabilities (to temperatures up to 600°C), and Low Framework Densities.  They exhibit permanent porosity with specific surface areas.  These materials have potential uses in areas such as Gas storage, separation, and catalysis. 5 Fig.3 : 1D, 2D & 3D structures of POFs
  • 6. 6 Schlenk Line Technique A Schlenk line (SL) is a valuable device in synthetic organic and inorganic chemistry, particularly for oxygen and moisture sensitive reactions. The Schlenk line, developed by Wilhelm Schlenk, is comprised of a twin manifold with a number of ports for using nitrogen/vacuum for multiple reactions/manipulations. Fig.4 : A Schlenk line system at IFG/KIT north campus research laboratory
  • 7. SELF-ASSEMBLED MONOLAYERS (SAMS)  Self-assembled monolayers (SAM) of organic molecules are molecular assemblies formed spontaneously on surfaces by adsorption and are organized into more or less large ordered domains. 7 Fig.5: Organic molecule attached to substrate forming SAMs SAM consisting of a head group, tail and functional end group is depicted in Fig.5 Common head groups include thiols, silanes, etc. SAMs are created by the chemisorption of "head groups" onto a substrate from either the vapour or liquid phase followed by a slow organization of "tail groups
  • 8.  Only since 1983 the formation of SAMs on metallic surfaces is investigated in a systematic fashion (first study by Nuzzo and Allara);  In this case, the anchor group is realized by the thiol function (HS–) that forms a stable gold thiolate (Au–S–R) when brought into contact with gold surfaces 8 Preparation of Self-Assembled Monolayers Fig 6: Generation of SAMs on Gold coated substrate
  • 9. CLICK CHEMISTRY AT ORGANIC SURFACES  "Click Chemistry" is a term that was introduced by K. B. Sharpless in 2001 and is one of the most common and reliable methods to link molecules covalently, and has many applications in a variety of disciplines. 9 Click Chemistry : Azide-Alkyne Cycloaddition
  • 10. 10 Fig.7 Schematic representation of their layer-by-layer synthesis on functionalized surfaces For fabrication of the porous organic nanomembranes, an alkyne containing molecule and an azide containing molecule are needed as building blocks and the reaction is catalysed by Tetrakis (acetonitrile) copper (I) hexafluorophosphate. The experimental studies begin with the fabrication of POFs with the help of molecules below by schlenk line technique for device fabrication. FABRICATION OF POFs
  • 11. SPIN COATING TECHNIQUE  Spin-coating is a process that involves depositing a small puddle of a fluid material on to the center of a substrate and then spinning the substrate at high speed (~3000 rpm).  The thickness of the film also depends on the viscosity and concentration of the solution and the solvent 11 Fig 8: spin coater unit After the fabrication of 8 cycles SAMs on gold coated mica substrate, Poly (methyl methacrylate) [PMMA] was fabricated on the top of mica substrate that helps in detaching the nano membrane from the mica substrate. The parameters chosen were 3000 rpm rotation speed and 120 sec for spinning. The post spin-coat samples were also baked at 80 OC for 5 minutes
  • 12. 12 Detachment of Membrane from Mica Substrate Following flow chart describes the detachment of membrane from substrate :
  • 13. Sr. No. Chemicals Required Amount 1 Propargyl alcohol 0.00173 ml 2 Propargyl bromide 0.00266 ml 3 Propargyl ether 0.00308 ml 4 Ethylene Ferrocene 0.00630 g 5 Phenyl acetylene 0.00330 ml 6 4- Fluorophenyl acetylene 0.00340 ml 13 SURFACE FUNCTIONALIZATION Table 1. Calculated amount of chemical reagents for end capping on the surfaces of HCP substrate for the surface functionalization. Fig9. Six test tube containing different end caps for surface functionalization
  • 14. CHARACTERIZATIONS TECHNIQUES  A number of different experimental methods are available for the characterization of SAMs (A) Contact angle measurements Drop shape analysis (DSA) is an image analysis method for determining the contact angle from the shadow image of a sessile drop and the surface tension or interfacial tension from the shadow image of a pendant drop. 14 Fig 10: Drop Shape Analyser – DSA100 (left) and drop image for contact angle measurement (right)
  • 15. 15 Measuring the contact angle is the simplest method to characterize organic SAMs generated by the reaction of thiols with gold. A drop of water or some other liquid is applied to the surface and photographed from the side. The wetting behaviour can be deduced from these contact angles. The surface shown in (a) is hydrophilic and consists of thiols with terminal OH functions. (b) Was taken for a CH3-terminated surface that was produced from a simple alkanethiol. In this case, the organic surface is water repellent (hydrophobic): the drop of water rolls off.
  • 16. (B) Infrared (IR) Spectroscopy As a matter of course, investigating the wettability of organic surfaces only with water or other solvents is not sufficient for a more detailed physico- chemical characterization. A deeper understanding requires for the determination of the exact chemical composition of the organic ultrathin layers, molecular orientation, and lateral arrangement. 16 Fig. 11: Bruker Vertex 80 equipped with a NB-MCT detector
  • 17. 17 CHARACTERIZATION RESULTS Contact Angle measurement of HCP on gold coated substrate before surface functionalization with different chemical reagents Date Average Contact Angle 26/05/2014 L =95.980 ; R =97.460 27/05/2014 L =101.46 ; R =98.900 Contact Angle Measurements- Substrate N3-(CH2)n-SH in Ethanol without chemical reagents Date Average Contact Angle 13/06/2014 L =72.62 ; R =72.92
  • 18. 18 S.No Average Contact Angles Chemical Reagents 1. 44.81o Propargyl Alcohol 2. 48.58o Ethylene Ferrocene 3. 57.82o Porpargyl Ether 4. 65.54o Phenyl Acetylene 5. 67.63o Propargyl Bromide Summary of Contact Angle measurement of [N3-(CH2)n-SH] on gold coated silicon substrate, surface functionalization with different chemical reagents
  • 19. S.No Average Contact Angles Chemical Reagents 1. 73.92o Ethylene Ferrocene 2. 68.18o Phenyl Acetylene 3. 55.93o Propargyl Bromide 4. 54.93o Propargyl Alcohol 5. 48.50o Porpargyl Ether 19 Summary of Contact Angle measurement of HCP on gold coated mica substrate, surface functionalization with different chemical reagents Summary of Contact Angle measurement of HCP on gold coated silicon substrate, surface functionalization with different chemical reagents S.No Average Contact Angles Chemical Reagents 1. 44.20o Ethylene Ferrocene 2. 45.65o Phenyl Acetylene 3. 47.03o Propargyl Alcohol 4. 50.40o Porpargyl Ether 5. 51.21o Propargyl Bromide
  • 20. CONCLUSIONS 20 In conclusion our results demonstrate the successful surface functionalization of highly stable freestanding nanomembrane via Copper-catalysed azide–alkyne addition. This process to surface functionalize POF nanomembrane represents a versatile strategy to chemically functionalize the nanometer thick membrane with tunable properties. The contact angle experiments clearly demonstrate that the surface functionalization of the membranes has a strong influence on the hydrophobicity of the membranes.
  • 21. THANK YOU !!