Polycaprolactone (PCL) was purchased from Aldrich, Lot # 01405KN. A 2.0 g sample of PCL [Aldrich, average M_n ca. 10,000 (GPC)] was weighed and dissolved in 98.0 g of NMP to make a 2.0 wt% solution. This solution was then placed under vigorous stirring for two days to ensure that the particles are fully dissolved. PCL's high solubility in NMP eliminates the need of filtering the solution for any undissolved crystals.

A 65 wt% water solution of para-hydroxybenzenesulfonic acid (PHBSA) was purchased from Aldrich, Lot # 03602TV. The PANi solution was doped with PHBSA (Aldrich, d=1.337) in a 1:2 ratio or for every repeat unit of PANi, two molecules of PHBSA were used. This represents "perfect doping" because, as can be seen in Figure 3, this ratio should ideally remove the double bond structures in the quinoid imine group if the reaction goes to completion. Thus, for every gram of PANi in solution, 0.08172 g of PHBSA was added. The solution turned green after doping. This doped PANi solution then undergoes continuous stirring for two days. The doped PANi solution was then diluted with NMP, and UV-vis spectroscopy was taken, with NMP as the reference, to verify its doping level by the appearance of characteristic peaks of doped PANi at wavelengths of about 420 and 800 nm.

PANi and PCL solutions were combined in various amounts to make blend ratios of various weight percentage compositions. The PANi/PCL blends made were in the ratios of 5:95, 10:90, 20:80, 30:70, and 40:60, with PCL being the dominant specie in all blend compositions. The blends were then subjected to continuous stirring to keep the mixtures homogeneous.

The samples for optical microscopy were from the thinnest films made by solution casting. The microscope used was Nikon Optiphot. Mettler FP82 Hot Stage unit, controlled by the Mettler FP80 central processor, was used to heat the samples and to study the true morphology of doped PANi/PCL blends after heating. Pictures were taken using Nikon Model HFX-II Automatic Microflex Photomicrographic System. They were taken before, during, and after heating, with emphasis on the crystal portions of the samples using cross polarization.

Electrical conductivity of the PANi/PCL blend samples was measured using Keithley 617 Programmable Electrometer by the two-probe method. The probes are made of platinum encased in a brass covering. The diameter of the probe is approximately 0.2 mm. They were placed approximately 5 mm apart, in the center of the samples. A current of approximately 10^-12 amperes was applied across the sample to measure the sample's resistance and conductivity was calculated using Ohm's Law, with the thickness of the samples at approximately 10^-3 mm.

UV-vis spectroscopy was taken of the samples. DMS 100S UV Visible Spectrophotometer from the Varian Company was used for the measurements. The data were collected by Lotus 1-2-3 and graphs were printed from Microsoft Excel 97. The samples with PANi composition above 20 wt% were diluted with NMP while those below 20 wt. % were measured as is. NMP was used as a reference for all UV-vis spectroscopy measurements.

Fourier Transform Infrared Spectroscopy (FTIR) was used to find evidence of intermolecular attraction between doped PANi and PCL. An indication of intermolecular attraction between the two compositions would be a shift in the 1724 cm^-1 peak, which is a result of the carbonyl functional group stretching in PCL. If there were an interaction between the polymers, the peak would shift in either direction by at least 10 nm. FTIR was performed by Ciba Specialty Chemicals Corporation in Tarrytown, NY. Infrared spectra were recorded using Mattson Polaris FT/IR Spectrophotometer and the samples were prepared by adding drops of the polymer blend solution onto a NaCl crystal.

Differential scanning calorimetry (DSC) was used to find the glass transition temperature (T_g) and melting point (T_m) of PCL and the blends and thermogravimetric analysis (TGA) was used to find the decomposition temperature of the compounds. DSC was performed using 910 Differential Scanning Calorimeter from DuPont Instrument and TGA was performed using Hi-Res TGA 2950 Thermogravimetric Analyzer from TA Instruments. The samples for DSC and TGA were prepared in similar manners. Approximately 10 grams of each sample were placed into small petri dishes. These were then placed in a vacuum oven at about 90 ^oC for one week to allow the NMP to evaporate completely. The residues were then removed from the dishes by scratching them with a metallic spatula, and placed into labeled glass vials. A small amount of each sample was placed into an aluminum hermite sample pan for both DSC and TGA tests. For DSC tests, 5.1000 mg of PCL, 7.9300 mg of 5:95, 9.1900 mg of 10:90, 11.1800 mg of 20:80, 8.1600 mg of 30:70, and 8.0300 mg of 40:60 were used. In DSC, an empty hermite sample pan was used as a reference. For the most accurate result, the mass difference between the two pans (the reference and the one containing the sample) should be less than 0.05 mg. For DSC tests, each sample was scanned twice. In the first scan, each sample was heated from 25 ^oC to 120 ^oC at 10 ^oC/min. The temperature was then held constant for 3 minutes to remove the old thermal history of the sample. Liquid nitrogen was then used to quench the temperature to about -170 ^oC. Once the temperature reaches -170 ^oC, the second scan begins. In the second scan, the temperature increases from -170 ^oC to 120 ^oC at a scanning rate of 10 ^oC/min. The results from the second scanning were then collected and printed.

TGA was performed for pure PANi EB. It was scanned from 25 ^oC to 900 ^oC at a scanning rate of 10 ^oC/min under nitrogen gas purging. The mass of the sample used for this measurement was 5.9850 mg. The purpose of TGA is to find the decomposition temperature of PANi. This is very important because it would set an upper bound for the temperature at which it can be heated to for DSC and hot stage studies without risking decomposition. DSC was used to find the number of T_g points and to plot a graph for analyzing phase separation with respect to PANi weight percentage composition. The presence of one T_g point in the blends would provide evidence of a single phase in the interpolymer complex whereas two T_g points would provide evidence of phase separation, meaning the mixture is not homogeneous. This information is important because a homogeneous mixture would indicate a high probability of the existence of hydrogen bonding interactions between doped PANi and PCL as shown in Figure 3.