**1. Introduction**

164 Macro to Nano Spectroscopy

A.Streitweiser, Jr., C. H. Heathcock. Introduction to Organic Chemistry. 2nd Ed. New

is presented.

York: Macmillan Publishing Co., Inc., 1981. Introductory organic text with a section on IR spectroscopy. Includes spectroscopic information as each family

> Infrared Spectrum (IR) is mainly used to study molecular structure and composition in substances and thus is also called molecular spectrum. When the sample is exposed to infrared light with continuously changing frequency, the molecule absorbs irradiation of certain frequencies and is subject to vibration or rotation, thus to cause the change of dipole moment. The molecule's transition from normal state to excited state weakens the intensity of the corresponding transmitted light in the absorption region, then the infrared software is used to obtain the IR spectrum. Started in 1970, Fourier Transform Infrared Spectroscopy (FTIR) was of high resolution and high scanning speed. It was not only limited to middle infrared (MIR), Spectrum ranges ultraviolet to far infrared section with the assistance of the beam splitter. The main direction of modern analysis, study and development is to combine technology of FTIR with that of the other instrument. For example, FTIR-TGA (Thermogravimetry Analysis) can be used to obtain thermogravimetric curve as well as the IR spectrum of the weight loss material, thus to determine the real composition of vapor generated in the various weight loss stages and the decomposition process.

> Ultraviolet and visible absorption spectrum are usually used to study unsaturated organic matter, especially the organic compounds with conjugated system. However, infrared spectroscopy mainly studies chemical compounds with change of dipole moment during vibration. Thus, almost all organic compounds, except single atoms and homonuclear molecule, absorb in the infrared spectrum region. Except for optical isomers, some high polymer of high molecular weight and compounds with slight difference in molecular weight, two compounds of different structure are unlikely to have the same infrared spectrum. Wave number position, number of wave peaks of infrared absorption band and the intensity of absorption band indicate the characteristics of the molecular structure, and thus can be used to identify the structural composure of the unknown objects or its chemical groups. The absorption intensity of the absorption band is related to the contents of the molecular composition or the chemical groups and can be used for quantitative analysis and purity identification. Infrared spectrum analysis has distinctive characteristic and can be used to test gas, liquid and solid samples. Lie other analysis methods, it can be used for qualitative and quantitative analysis and is one of the effective methods for chemical compound identification and molecular structure elucidation.

Application of Infrared Spectroscopy in Biomedical Polymer Materials 167

terminator and emulsifier; 2) additives: plasticizers, stabilizer, filler and colorant etc.; 3)

Compared with ordinary organic substance, polymer-a long chain connected by multiple monomer units through covalent bonds—features diversified and designable structure, with very high mechanical strength and non-fixed molecular weight. Polymer is partially

Repetitive unit structure

Molecular weight and its distribution

Copolymer composition and

Branching and Cross-linking

Physical condition

Heterogeneous structure and

Crystallization

Orientation

morphology

sequence distribution

Stereospecificity

crystallized or non-crystallized and provides the properties of elastomer and fluid.

**2.3 Basic requirements of biomedical polymer and common materials** 

Aggregation structure

resistance and wear resistance for different application.

Requirements on body effect of biomedical polymer

Biomedical polymer is directly applied to human body and is closely related to human health. Therefore, the materials used for clinic should be strictly controlled, otherwise, it may cause adverse effect instead of life saving. Below are requirements on properties and

1. Resistance to biological aging: polymer for long-term implantation should have good

2. Physical and mechanical stability: different strength, elasticity, size, stability, fatigue

unreacted monomer, residual catalyst, etc.

Chain structure

Table 2. Polymer materials

Polymer Material

biological stability.

performances of the biomedical polymer:

3. Easy for processing and molding 4. Proper materials with reasonable cost

5. Convenient for sterilization.
