Degradation of Polymers Long Lor Chem 4101 Fall 2010 December 13, 2010

Polymers Polymers are large macromolecules containing two end groups and longs chains of repeat units. They are often derived from petroleum Billions of kgs of polymers are produced annually. In the 1990, production close to 150kg of polymer per person in US Degradation of polymers is done by use of UV light, Ozone cracking, hydrolysis, and heat.

Analyte Styrene is derived from petroleum, performing alkylation of ethylene and benzene Production of polystyrene in the US and Canada is approximately 2.2 billion kgs The molecular weight, mw, of PS will depend on the original purpose – Avg. mw range: g/mol Repeat unit: g/mol

Experimental Problem: The world relies heavily on fossil fuels. Polymers, in certain conditions, will depolymerize back into monomer. Could we use this process to get enough monomer to perform another polymerization. Hypothesis: Detection of polymer degradation back into monomer is quantifiable using proton NMR or IR.

Relevance of Problem The energy crisis over recent years has become more evident, its clear that we humans have relied on consuming fossil fuels for everything. There have been recent developments in other areas, such as solar technology, but that is still a ways away. The use of petroleum based materials in polymers is something that this analytical problem hopes to address. Upon detecting the depolymerization of polymer back to monomer, there will less consumption of fossil fuel.

Techniques considered Technique AdvantagesDisadvantages SEC (GPC) Well defined separation time High molecular weight detection Requires 10% Mw difference Prior filtration required GC-MS Low LOD, about 0.25pgHigher Temperature to make gas state High cost ESI-MS Detects high molecular weights > 100,000Da Does not handle Matrix well Difficult to clean HPLC-MS Low LOD Gradient solvent system Excess solvent gas when changing over to MS detector

MALDI-TOF Advantages Can separate high mw compounds Low sample concentration – Femto mol concentrations Low background noise Selective mass charge analysis Multiple sample analysis Disadvantages Standards are required for MALDI Limited mass range Relative Instrument cost

Instrument LaserToF LT3 Plus Laser – Pulsed UV 337nm Nitrogen Mass accuracy – 20ppm Mass range > Da. Sensitivity < 1femtomol Large dynamic and linear range Cost around $

Sample preparation Obtain possible degradation samples of polystrene MALDI requires that there be a standard to compare to. – Styrene standard would be used ProteoMass ™ Aldolase – (39.2 kDa) Load samples into LaserToF and run sample

Expected results An example of MS spectrum for MALDI-ToF, M.W. 2.3kDa If the degradation of polystyrene to monomer styrene occurred, there would be two peaks that separate Gaussian peaks – Styrene at low m/z – Polystyrene at high m/z Although not quanitative in the approach, this technique will the extent of depolymerization.

Conclusion The analysis of degradation of styrene from polystyrene using the MALDI-TOF technique, the technique will provide sufficient separate peaks representing the degradation of polystyrene. If separation is efficient enough, further analysis of degradation can be determined qualitatively for use in obtaining monomer from recycled polymers.

References “Degradation of polymer in nature.” Health Envrionment & Regulatory Affairs (HERA), Dow Corning. Ref # , accessed Nov Katz, David A. “Polymers” 1981, Accessed Oct “Basics of Polystyrene Production” Chemical Engineering Tools and Information. Young, Sandra. MALDI-TOF MS. LaserToF LT3 Plus. Scientific Analysis Instruments. Accessed Dec