Hybrid photopolymerization has the potential for solving the oxygen inhibition and moisture problem that plagued the free-radical and cationic photopolymerization reactions respectively. The problem, however, with the hybrid system is the deficiency in the fundamental knowledge of the reaction in the system. This project tends to address these deficiencies by studying hybrid systems in order to understand how experimental variables affect oxygen, moisture and alcohol sensitivity. This understanding will be archived by the following objectives;
Determine the kinetic rate constants for the hybrid systems.
The kinetic rate constant, activation energy and Arrhenius constant of the hybrid systems will be obtained from Raman spectroscopy method.
Model oxygen- diffusion-effect in hybrid systems.
An oxygen-diffusion-model will be developed incorporating energy balance, specie balance and light attenuation parameters.
Reduce oxygen diffusion in hybrid monomer films through formulation and processing variable selections.
Hybrid monomer molecule and monomer mixture will be polymerized to obtain the conversion profile; the cure sample will be investigated to obtain the functional group conversion versus depth by Raman spectroscopy and microscopy respectively. The physical properties of the resulting product will be checked in order to determine the least oxygen diffused product.
Develop practical hybrid monomer formulations for industrial applications.
Hybrid systems that can be replicated on the industrial scale will be formulated. These systems will be suggested based on availability, cost and resulting physical properties displayed as investigated in Objective three.
IV. Research Plan
A Overview
In this study, a series of hybrid systems will be considered; monomers of these systems will have different functionality present, like those in Figure 5. Hybrid monomer molecule, that is, a single monomer molecule with two moieties (such as acrylate and epoxide) and hybrid mixture formulation that will contain separate molecules for each moiety (i.e. acrylate will be mixed with epoxide). The photoinitiator systems for this study will be expanded to include α-cleavagable free-radical photoinitiator, such as dimethoxyphenylacetophenone (DMPA) shown in Figure 1, and cationic photoinitiator salts as shown in Figure 3. Raman spectroscopy will be used for in-situ investigation of polymerization of samples. Raman microscopy will be used to obtain profiles of functional group conversion at various depths. These methods are based upon a non-destructive Raman scattering technique which provides information about the vibrational and electronic states in a confined system.{{8 Cai,Ying 2006}} The method is particularly well suited for detection of chemical bonds and their changes during reaction.
B. Objective #1 Kinetic Study of the Hybrid Systems
This week’s lab was the third and final step in a multi-step synthesis reaction. The starting material of this week was benzil and 1,3- diphenylacetone was added along with a strong base, KOH, to form the product tetraphenylcyclopentadienone. The product was confirmed to be tetraphenylcyclopentadienone based of the color of the product, the IR spectrum, and the mechanism of the reaction. The product of the reaction was a dark purple/black color, which corresponds to literature colors of tetraphenylcyclopentadienone. The tetraphenylcyclopentadienone product was a deep purple/black because of its absorption of all light wavelengths. The conjugated aromatic rings in the product create a delocalized pi electron system and the electrons are excited
Solid triphenylmethanol (0.200 g, 0.768 mmol) and sulfuric acid (2 mL) were added to a reaction tube, which was then ground using a glass rod until it dissolved and turned a dark orange color. The mixture was then added dropwise via a glass pipette into another reaction tube containing methanol (1 mL). An extra amount of methanol (2 mL) was used to transfer the rest of the contents of the first reaction tube. Formation of crystals was facilitated by scratching the side of the tube and adding additional methanol until the color changed to an off-white color. The contents of the tube were then vacuum filtered with water and the resulting crude product was weighed and then recrystallized using hot methanol to form triphenylmethyl methyl ether (0.051 g, 0.186 mmol, 24.2%). The melting point was 81 – 83˚
Physical Chemistry Laboratory Manual, Physical Chemistry Laboratory, Department of Chemistry, University of Kentucky, Spring 2006.
First, A (3.348 g, 0.031 mol) and triethylamine (6.060 g, 0.060 mol) were added to a glass flask. Then, B (5.850 g, 0.030 mol) was added dropwise to the resulting reaction mixture over a period of 2 h, and the temperature was maintained at 5 °C. The reaction mixtures were carefully maintained at 80 °C for another 5 h. Finally, the reaction mixture was washed with diethyl ether, separated by reduced pressure suction filtration, and dried in a vacuum oven at 100 °C for 12 h to afford a white solid powder, namely, poly-N-aniline-phenyl phosphamide (PDPPD) in 93%
The purpose of the experiment is to study the rate of reaction through varying of concentrations of a catalyst or temperatures with a constant pH, and through the data obtained the rate law, constants, and activation energies can be experimentally determined. The rate law determines how the speed of a reaction occurs thus allowing the study of the overall mechanism formation in reactions. In the general form of the rate law it is A + B C or r=k[A]x[B]y. The rate of reaction can be affected by the concentration such as A and B in the previous equation, order of reactions, and the rate constant with each species in an overall chemical reaction. As a result, the rate law must be determined experimentally. In general, in a multi-step reac...
rapid development of polymer chemistry after World War II a host of new synthetic fibers
The purpose of this lab was to better understand how the vibrational frequencies of five different compounds were affected by the molecular shape as well as substitution. We were able to determine this using an IR spectrum of each compound as well as by predicting the vibration frequencies by using Gauss View. Furthermore, students were also able to demonstrate their skills in reading IR spectrums.
Polymers are formed during dehydration synthesis reactions, as a covalent bond forms between two monomers when a water molecule is lost (Collin County Community College, 2014). In hydrolysis, the covalent bond between monomers in a polymer is broken by the addition of a water molecule as the hydrogen in the water molecule attach...
The synthesis of polymers starts with ethylene, (or ethene). Ethylene is obtained as a by-product of petrol refining from crude oil or by dehydration of ethanol. Ethylene molecules compose of two methylene units (CH2) linked together by a double carbon
To examine the interaction between two molecules in solution without isolating the compound Jobfs method is used. Although unstable compounds tend to be generated, this is not a reflection of weak interactions. In some cases, the transition metal species cannot be crystallized from the solution and separated from the other species present. Without Jobfs Method this composition can be very difficult to deduce.
Thickett, Geoffrey. Chemistry 2: HSC course. N/A ed. Vol. 1. Milton: John Wiley & Sons Australia, 2006. 94-108. 1 vols. Print.
Ever since I began studying science and mathematics at all levels of educations I have always had an interest in the production of useful materials. In the growing turmoil of today; a world full of global warming and diminishing resources, questions often arise in my mind such as, "can we make a more efficient, more durable and a renewable resource that will overshadow fossil fuels? and have less of an impact on our environment?" Up to now, I have not found a solution to these questions and answering these questions is a personal aspiration of mine which I aim to fulfil by achieving a degree in Chemical engineering and eventually I will contribute to the field in my own unique way. The debate surrounding sustainable energy fascinates me, having recently learned from personal research I have understood what an authoritative role chemists and chemical engineers play in the industry at the present time and how, by working as a team, they contribute to an improved future for the whole world. However, one of the main reasons that has single-mindedly driven me this far to want to study chemical engineering is a book I have read, “Beyond the Molecular Frontier: Challenges for Chemistry and Chemical Engineering” While reading this book, I had solidified my understandings of what chemical engineering is all about. Also, one of the main processes mentioned was polymerisation and is something I already study in A-level chemistry, it is something that not only interests me, but is a personal career aspiration of mine. Reading this book gave me a determination to be the person who helps improve the future of the industry and provide an answer to the questions I always ask myself by studying this degree.
23. S. Alwarappan, S. Boyapalle, A. Kumar, C.-Z. Li and S. Mohapatra, J. Phys. Chem. C, 2012, 116, 6556–6559
chains instead of hydrogen atoms. Cross-linking is another way in which the polymer can be made stronger. This involves ultraviolet radiation that bombards the polymer with electrons and formulates bonds between the molecular chains of the polymers. This is like linear polyethylene but different in that it is more impact resistant, and it has a much higher density. This allows it to be stored or be used with different chemicals that would normally cause the polymer to desolve.3 This can start to become a problem because as the polymer continues to become chemically enhanced. So the ways of dissolving and recycling the polymer become more difficult.
Plontke, R. (2003, March 13). Chemnitz UT. TU Chemnitz: - Technische Universität Chemnitz. Retrieved April 1, 2014, from http://www.tu-chemnitz.de/en/