Physics and Chemistry of Hybrid Organic-Inorganic Materials Professor Douglas A. Loy Visiting from the University of Arizona, United States

Syllabus Rm 410 Wednesdays 13:45-14:35, 14:40-15:30 Fridays 13:45-14:35, 14:40-15:30 Last day of class is June 11th 4 quizes No final exam Attendance and participation are graded

Course website For lecture slides and other info. Not at HIT website, at Loy research website:http://www.loyresearchgroup.com/ • Go to loy research group home page and select “courses” on menu at top. • Class website: “Chemistry and Physics of Materials Harbin Institute of Technology ” is the second entry. Direct url:http://www.loyresearchgroup.com/harbin-institute-technology---hybrid-materials-course.html

Lectures Lecture 1: Introduction to hybrids May 14 Lecture 2:Structures of Hybrids May 14 Lecture 3: Properties of Hybrids May 16 Lecture 4:Physics of phase separation & solutions May 16 Quiz 1 May 21 Lecture 5:Naturally occurring hybrids May 21 Lecture 6: Making hybrids by physical mixing of materials May 23 Lecture 7:Polymerizing monomers to make hybrids May 23 Quiz 2 May 28 Lecture 8: Polysilsesquioxanes May 28 Lecture 9: POSS systems May 30 Lecture 10: Bridged polysilsesquioxanes May 30 Quiz 3 June 4 Lecture 11: Polymerizing organic monomers in inorganics materials June 4 Lecture 12: Polymerizing inorganic monomers in organic polymers June 6 Lecture 13: Surfactant templating materials June 6 Lecture 14 Frontiers in hybrids June 11 Quiz 4 June 11

Example of quiz 1: Quiz 1: Write your name, and ID number at top of page. Then write the answers to 1-10 in English. What is a hybrid organic-inorganic material. Write a short definition. 2) Please, give an example of a hybrid organic-inorganic material? 3) Name three benefits of hybrid organic inorganic materials compared with organic polymers. 4) What analysis can you use to determine the thermal stability of a hybrid organic inorganic material in the laboratory? 5) How can you determine if a hybrid organic-inorganic material is crystalline or amorphous?   6) How do you measure the strength of a hybrid organic inorganic material? 7) How can you tell if a hybrid organic inorganic material is one phase or two phases? For a one phase solution to spontaneously separate into two phases, the free energy for separation must be? 9) What are the two types of phase separation mechanisms observed with hybrid organic inorganic systems?  10) Explain what surface tension is and why small particles have higher surface energy than large particles.  

What are hybrid organic-inorganic materials? Mixtures of organic materials and inorganic materials Hybrid organic inorganic materials are also called composite materials. An example of a composite material is an automobile tire. Very important materials for 21st century economy

Lecture Objectives Identify hybrid organic inorganic materials List benefits of using hybrids Basic ways hybrids are put together Understand what is meant by organic, inorganic, monomer, polymer and material. Understand the size (length scales) in hybrids know applications for hybrid materials List hybrid organic-inorganics found in nature The lecture objectives are meant to help you focus on key topics for the course. Find the answers to the above questions and you will be prepared for the quizes.

Identifying hybrids:Both organic and inorganic materials combined IN tires the organic phases are the polyisprene rubber and nylon belts while the steel belts and carbon and silica filler are the inorganic phases. The length scales for the steel and nylon belts are very large, but that of the silica and carbon is on the 100 nanometer length scale. Centimeter Length scales Steel, silica, & carbon – inorganic (strong) Poly(isoprene) rubber – organic (flexible, adhesive, elastic)

Identifying hybrids: often have two phases A close up look at the rubber in the tire shows about 30 wt% silica particles The inorganic silica particles are 10-500 nm in size. The organic (polyisoprene rubber) is continuous The carbon or silica filler is more opaque to the electrons in the transmission electron microscope, so it appears black.

Identifying hybrid organic materials with Scanning electron microscopy Inorganic particle Organic polymer Scanning electron microscopy uses electrons reflected from the surface for visualization just like a light microscope uses visible wavelengths of light. The silica particles are very white because they are accumulating electrons and becoming charged. Features are often too small to see with the eye

Identifying Hybrid organic-inorganic materials Hybrids may be a composite of multiple phases or a single hybrid phase. multiphase composite – examine by SEM, AFM, TEM Single phase material – elemental analysis Quick method: burn the material and see if there is a residue. Organic burns, most inorganic will leave a residue

Benefits of Hybrid Organic Inorganic Materials Stronger and stiffer than organics Tougher and more flexible than inorganics Less flammable than organics When melted, more viscous (non-dripping) Tailored optical properties (refractive index, transparency, scattering, absorptions) High surface area porous materials Hybrids may not have all of the beneficial characteristics. They generally have one or more if they are to be useful.

How are hybrids put together? Physically mixing inorganic materials and organic polymers Polymerizing an organic monomer in an inorganic material Polymerizing an inorganic monomer in an organic material or polymer Polymerizing a monomer with both organic and inorganic parts This slide is about the synthesis of hybrids. The general strategies you would use to make them in a laboratory.

Organic monomers react by polymerizing into macromolecules Equivalent to this shorthand structure To introduce you to what monomers and polymers are, this slide shows you a styrene monomer that will combine with other styrene molecules in a chain reaction to create a macromolecule or polymer (called polystyrene). As many as 20,000 monomers may be linked together to make a single macromolecule

Polymerization of inorganic or hybrid monomers to form materials Hydrolysis: Condensation: Net Polymerization: The same polymerization process can be used to prepare metal oxides or silica from monomeric precursors or hybrid materials directly from the polymerization of a hybrid monomer. These polymerization routes are just one of the four strategies for making hybrids mentioned earlier in the lecture. Shown here for formation of a silsesquioxane

Hybrid from organic polymer and inorganic monomer Solid Organic Polymer Pre-made inorganic particles dissolve or melt solution or molten organic polymer inorganic particles dispersed in solution or melted polymer This is a physical mixing process where preformed particles are dispersed into a melted organic polymer or a polymer dissolved in a solvent. Then the melted polymer is cooled to afford a hybrid of continuous phase polymer with dispersed inorganic particles or the solvent is evaporated leaving a similar hybrid. Cool melt below Tg or evaporate solvent

A hybrid might have silica nanoparticles mixed in with the polystyrene The effect of having the particles dispersed in the polymer is to improved the thermal and mechanical propertiescompared to the polymer without the particles. Such hybrids have higher glass transition temperatures, and are stronger, more flame resistant

Hybrid from organic polymer and inorganic monomer Inorganic particle Organic polymer This is a hybrid in which the preformed silica particles were mixed with a ethanol solution of Nafion (an organic polymer electrolyte) before casting as a film.

Hybrid from organic polymer and inorganic monomer Inorganic Monomer (liquid) & catalyst Solid Organic Polymer melt or dissolve Mixture of Organic polymer and Inorganic Monomer & catalyst Solution or emulsion In this hybrid formation strategy, an inorganic monomer and reactants and catalyst is dissolved into the solid organic polymer where it polymerizes, phase separates to form an in-situ (in place) generated particle. This approach is less difficult to process than the physical mixing process mentioned on the previous two slides. Monomer polymerizes & forms particles

Preparation by adding organic monomer into pores in inorganic material then polymerizing organic Monomer (liquid) & catalyst Porous Inorganic Material Monomer must be soluble in polymer Mixture of Organic Monomer & Inorganic Material In this strategy, a liquid organic monomer is adsorbed into the pores in an inorganic material where it is polymerized to form an organic polymer. The holes in the inorganic material act to template the polymer and limits its growth. Monomer polymerizes & fills pores with particles

Hybrid Monomer in solution Polymerize monomer that has both organic and inorganic parts connected together with bonds Hybrid Monomer in solution Sol-gel polymerization Hybrid organic-inorganic particles dispersed in solvent In this strategy, the hybrid monomer with both organic and inorganic components in a small molecule is polymerized to afford a polymeric hybrid. As these are often highly crosslinked, the growing polymer phase separates out as particles and the particles, dispersed in the solution can either be cast to afford a film, collected and dried as a free flowing particulate solid or allowed to percolate and form a gel in which the solvent and the particles form interpenetrating phases. When the solvent is evpaorated, the result can be a material with a very high surface area. Hybrid Coating Hybrid Gel Hybrid Particles

Structure of Hybrids atomic (Angstrom) macromolecular (nm’s) 1 micron Structure of hybrids can be categorized at diffferent scales. At the very shortest length scale (measured by NMR and XRD) is the atomic structure. Longer length scale structure can be evaluated by smaller angle XRD and NMR, but also gel permeation chromatography or light scattering. Colloidal nanostructure is best characterized by electron microscopic techniques, surface area analyses and light scattering. 1 micron Microstructure or morphology (> 100 nm) Colloidal or nanostructure (< 100 nm)

Length Scales This slide is to give you perspective on the size scales described in these lectures.

Applications of hybrid materials Coupling agents For composites Protective coatings Toughened Composites There are many applications for hybrid materials. Many, but not all, are based on organosilicon hybrids. Coupling agents used for tires are low Tg oligomers of organotrialkoxysilanes that are used to interconnect the silica filler now used in tires with the polyisoprene rubber. Protective coatings typically have a metal alkoxide component covalently linked to a polymerizable organic group that cures into a dense impervious coating to prevent water from artwork or construction, gases from passing through containers or OLED packaging, or aqueous corrosives to metal surfaces. Toughned composites are organic polymers that have been modified with inorganic groups that will crosslink the polymers and improve their toughness. Tethers for Bio-molecules Chromatographic Materials (X-Bridge ®, Waters) Photoresists for Lithography Photographs courtesy of Gelest, Inc. and Waters Co.

Applications of hybrids Impermeable hybrids to prevent loss of pressure Strong, low density structural materials Nylon-clay hybrids are now used commercially in truck bed materials, and to make tennis balls less permeable to air. They have also been used to help keep oxygen away from photovoltaic elements in solar panels. Protective coatings on solar panels

More applications of hybrid materials Low K Dielectrics Adhesives Sensor coatings POSS have been widely used as low k dielectric materials for microelectronics. Adhesive based on POSS or other inorganic materials as filler and to improve abrassion resistance are widely available. A number of polysilsesquioxane have been used as coatings for surface accoustic wave guide sensors and electrochemcial sensors. A number of porous hybrids, particularly the bridged polysilsesquioxanes, and mesoprous surfactnan templated mateirals have been used as metal ion scavengers to remove toxic and potentially valuable metals from water. Optical coatings includes those designed to correct chromatic aberrations and to provide scratch resistance to optics. A number of hybrid encapsulants have been developed and are availble. Those with low tg components are suitable for wide temperature range fluctuations due to CTE mismatch. Metal Scavenger “resins” Optical coatings encapsulants Plus ceramic precursors (e.g. SiC)

Hybrid Organic-Inorganic materials are common in nature Animals Organic phase is biopolymer Nacre Plants phytolith Argonite (CaCO3) plates as inorganic with protein (polyamide) as organic Hybrids are also commonly used by nature to improve strength of normally very weak materials. Bone, teeth, spines in echinderms Mussel shells, sponges, diatoms and corals are composed of hybrid organic-inorganic materials Carbohydrates are the template and organic phase

Summary: Hybrid materials are combinations of organic and inorganic components the organic and inorganic parts can be in one phase or in separate phases. Single phase hybrids are often made from hybrid monomers Hybrids can have improved mechanical properties, thermal & chemical stability, and modified optical properties. Hybrids have many applications