membrane_synthesizing.pdf

1.Purpose:

The purpose of this protocol is to offer a guideline for synthesizing thin membrane specimens of SMPs, which are suitable for accurate tensile tests with Dynamic Mechanical Analyzer (DMA).

2. Materials and Equipment:

tert-Butyl Acrylate, Poly(ethylene glycol) Dimethacrylate, Di(ethylene glycol) Dimethacrylate, 2,2-Dimethoxy-2-Phenylacetophenone

Centrifuge Polypropylene Tubes (50ml), Tube Racks, Balance, Pipette, Pipet Tips, Transfer Pipets with Standard Bulb, Vortex Genie 2 Mixer, Weigh Boats, Spatula, Microscope Glass Slides (75mm*25mm), Thin Rubber Sheet (1mm thick), Clips, Knives, Tissue Culture Dishes, UV Oven, Incubator

3.Steps:

(As an example, the following steps are for the synthesizing of 10 wt% specimens. For 20, 40 wt% specimens the procedure is the same but with different chemical ratios, refer to Table 1. The absolute amount of each chemical is subjected to change based on the number of specimens need to be synthesized.)

Step1: Put the polypropylene tube on the balance, and then zero the balance. Step2: Transfer 1.24ml DEGDMA into the polypropylene tube using a pipette with

pipet tip. Measure the mass using the balance.

Step3: Change a new pipet tip. Transfer 2.84ml PEGDMA into the polypropylene tube using a pipette with pipet tip. Measure the mass using the balance. Make sure the mass ratio of DEGDMA: PEGDMA is 3:7.

Step4: Change a new pipet tip. Transfer 45.92ml tBA into the polypropylene tube using a pipette with pipet tip. Measure the mass using the balance. Make sure the mass ratio of DEGDMA: PEGDMA: tBA is 3:7:90.

Step5: Put a weigh boat on the balance. Zero the balance. Add the photoinitiator (2,2- Dimethoxy-2-Phenylacetophenone) to the weigh boat using a spatula until the mass of the photoinitiator is 0.1% of the mass of the polymer solution.

Step6: Add the photoinitiator to the polymer solution. Screw the cap on tightly. Put the tube on the mixer for 1-2 mins. Make sure the photoinitiator is fully dissolved.

Step7: Sandwich two rubber sheets between two glass slides as spacers. Clip the glass slides at two ends. (Fig.1)

Step8: Inject the polymer solution into the space between two glass slides using a transfer pipet with bulb.

Step9: Put the clipped glass slides into a tissue culture dish. Do this carefully to avoid leaking of the polymer solution. Put the dish into the UV oven.

Step10: Turn on the oven. Expose the glass slides containing polymer solutions to UV light for 20 mins.

Step11: Turn off the UV oven. Transfer the dish into the incubator. Equilibrate at 70°C for 60-90 mins.

Step12: Cool down the specimen. Remove the glass slides to get the polymer membrane. Cut the membrane to desired size if necessary.

Table1. Mass ratios and volume ratios of three chemicals for 10, 20 and 40 wt%

Fig1. Clipped glass slides separated by rubber spacers