高分子科学导论Supramolecular

1、Supramolecular polymers,四川大学化学学院,超分子聚合物,Introduction to polymer science,Basic of the Supramolecular,Supramolecular polymer,A supramolecular polymer is a polymer whose monomer repeat units are held together by noncovalent bonds. Non-covalent forces that hold supramolecular polymers together include c

2、oordination, - interactions, and hydrogen bonding.,Supramolecular polymer,Jean-Marie Lehn,Colloid Early 20th century,Linear polymer from 1930,Supramolecular polymer from 1997,Donald J. Cram,Charles J. Pedersen,Definition of Supramolecular polymer,Polymeric arrays of monomeric units that are brought

3、together by reversible and highly directional secondary interactions, resulting in polymeric properties in dilute and concentrated solutions, as well as in the bulk.,molecular chemistry atom + atom molecular（covalent）,supramolecular chemistry molecular + molecular supramolecular（noncovalent）,Intermo

4、lecular Interactions,“Supramolecular Chemistry is the chemistry of the intermolecular bond, concerning the structure and functions of the entities formed by the association of two or more chemical species.” (by Jean-Marie Lehn) Covalent bond C-O bond340kJ / molC-C bond360kJ / mol C-H bond430kJ / mol

5、C=C bond600kJ / mol C=O bond690kJ / mol Driving Force for the Formation of Supramolecular Structures Hydrophobic interaction 40 kJ/mol Electrostatic interaction - 20 kJ/mol Hydrogen bond interaction 1230 kJ/mol Van der Waals interaction 0.4-4 kJ/mol Cation- interaction 5-80 kJ/mol - interaction 0-50

6、 kJ/mol Coordination interaction (Host-guest interaction),van der Waals Interaction:Sticky Secrets of the Gecko,The toes of the gecko have a special adaptation that allows them to adhere to most surfaces without the use of liquids or surface tension. the attractive forces that hold geckos to surface

7、s are van der Waals interactions between the finely divided setae and the surfaces themselves. Every square millimeter of a geckos footpad contains about 14,000 hair-like setae. Each seta has a diameter of 5 micrometers.,Hydrophobic interaction,Hydrophobic molecules tend to be non-polar and thus pre

8、fer other neutral molecules and non-polar solvents. Hydrophobic molecules in water often cluster together forming micelles. Water on hydrophobic surfaces will exhibit a high contact angle.,Hydrogen bond,A hydrogen bond is the attractive interaction of a hydrogen atom with an electronegative atom, li

9、ke nitrogen, oxygen or fluorine. The hydrogen must be covalently bonded to another electronegative atom to create the bond. These bonds can occur between molecules (intermolecularly), or within different parts of a single molecule (intramolecularly).,The Hydrogen bonds can vary in strength from very

10、 weak (1-2 kJ/mol) to extremely strong (155 kJ/mol), Typical values include: FH. :F (155 kJ/mol or 40 kcal/mol) OH. :N (29 kJ/mol or 6.9 kcal/mol) OH. :O (21 kJ/mol or 5.0 kcal/mol) NH. :N (13 kJ/mol or 3.1 kcal/mol) NH. :O (8 kJ/mol or 1.9 kcal/mol),- stacking,- stacking are caused by intermolecula

11、r overlapping of p-orbitals in -conjugated systems, so they become stronger as the number of -electrons increases. - stacking interactions act strongly on flat polycyclic aromatic hydrocarbons such as anthracene, triphenylene, and coronene because of the many delocalized -electrons.,- stacking (arom

12、atic interaction). Weak electrostatic interaction between aromatic rings. There are two general types: face-to-face and edge-to-face:,Face-to-face -stacking interactions are responsible for the slippery feel of graphite. Similar -stacking interactions help stabilize DNA double helix.,Face-to-face,ed

13、ge-to-face,Self-assembly,Self-assembly is a term used to describe processes in which a disordered system of pre-existing components forms an organized structure or pattern as a consequence of specific, local interactions among the components themselves, without external direction. That is without gu

14、idance or management from an outside source (other than to provide a suitable environment).,molecule components,supramolecular,device,components,Self-assembly,Self-assembly can be classified as either static or dynamic. In static self-assembly, the ordered state forms as a system approaches equilibr

15、ium, reducing its free energy. However in dynamic self-assembly, patterns of pre-existing components organized by specific local interactions are not commonly described as self-assembled but self-organized.,Unit of the Supramolecular,Unit of Supramolecular,Based on hydrogen-bonding Based on - stacki

16、ng Based on coordination (Host-guest) Based on miscellaneous interactions,Based on hydrogen-bonding,Liquid Crystalline supramolecular developed by Lehn, based on triple hydrogen bonds,Based on hydrogen-bonding,Based on hydrogen-bonding,Diblock copolymer,Tautomerization,Homodimerization,Heterodimeriz

17、ation,UPy-UPy,UPy-Napy,1,8-naphthyridine,Ureidopyrimidinones,Based on - stacking,triphenylenes,R = C5H11, C9H19, C11H23, C6H13,R = C3H7CH(CH3)C3H6CH(CH3)2,R = (C2H4O)2CH3,Based on coordination,PF6-,PF6-,PF6-,Based on miscellaneous interactions,Characteristics of the Supramoleculars,Facile and econom

18、ic synthesis Self-assembly involves the aggregation of molecules and macromolecules to thermodynamically stable structures which are held together by weak noncovalent interactions. Reversibility and Self-repairing Reversible aggregates that can break and recombine on experimental time scales Environ

19、mental responsive The noncovalent interactions are sensitive to environment change, such as solvent, temperature, pH, etc.,Characterization of the Supramolecular,Characterization of the Supramolecular,Detection of surface: AFM, SEM, STM, etc. Characterization of chemical structure FTIR, 1H-NMR,MS (M

20、ALDI-TOF), etc. Determination of molecular weight GPC Representation of viscosity Ubbelohde viscometer,SPM: Scanning Probe Microscopy,STM: scanning tunneling microscope tunneling of electrons between probe and surface AFM: atomic force microscope measuring of the force on the probe MFM: magnetic for

21、ce microscope AFM with magnetical probe,Microscopy,a) POM (polarizing optical microscopy); b) SEM (Scanning electron microscope); c) TEM (Transmission Electron Microscope); d) AFM,Investigating the assembly morphology of the supramolecular,1H-NMR,MALDI-TOF-MS,Matrix-assisted laser desorption/ionizat

22、ion (MALDI) is a soft ionization technique used in mass spectrometry, allowing the analysis of biomolecules (biopolymers such as proteins, peptides and sugars) and large organic molecules (such as polymers, dendrimers and other macromolecules), which tend to be fragile and fragment when ionized by more conventional ionization methods. The ionization is triggered by a laser beam (normally a nitrogen laser). A matrix is