Measurement of Mechanical Properties of Single Polymer Chains by Using Float-Type Optical Trapping

2006 Fiscal Year Final Research Report Summary

• Project/Area Number: 17350107
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Polymer/Textile materials
• Research Institution: Kyoto University
• Principal Investigator: TAKIGAWA Toshikazu Kyoto University, Graduate School of Engineering, Professor, 工学研究科, 教授 (50201603)
• Co-Investigator(Kenkyū-buntansha): HORINAKA Jun-ichi Kyoto University, Graduate School of Engineering, Assistant Professor, 工学研究科, 助手 (00313734)
• Project Period (FY): 2005 – 2006
• Keywords: Optical Trap / Polymer Chain / Mechanics / Rheology / Organic Solvent

Research Abstract

We have assembled a type of measurement systems to obtain the mechanical properties of single polymer chains in solution. Since very small spring constants are expected for flexible polymer chains such as polystyrene, the optical trapping has been used for the detection of force against the chain extension. Most of synthetic polymers are soluble to organic solvents, meaning that such mechanical measurements should be conducted in organic solvents. Considering the low refractive indices of organic solvents, a float-type optical trapping as well as the former-type optical tweezers has been tested. The float-type optical trapping is expected to trap a particle dispersed in a medium of any refractive index, but stable trapping has not been easily attained. Instead, a particle has been steadily trapped by a former-type optical trapping when the trapping conditions have been carefully determined. Using the assembled measurement system, the elasticity constant of a polystyrene chain in the snall deformation region has been obtained.