I have a photosensitive resin MSDS. It lists a mixture of 1,6-Hexanediol diacrylate ($\ce{C_{12}H_{18}O_4}$) with its proper CAS number and Polyurethane acrylate together with the CAS number of "Butyl acrylate/methyl methacrylate/methacrylic acid copolymer" with the formula (or rather, formulas) of $\ce{(C7H_{12}O2.C5H8O2.C4H6O2)_x}$. There's also the Photoinitiator 1-Hydroxycyclohexyl phenyl ketone listed. The additives of color and reaction inhibitor are most likely irrelevant for the actual question, so I leave them out.
My organic chemistry is somewhat rusty, but the first part of the compound I can identify as having the setup $\ce{H2C=CH-CO-O-C6H12-O-CO-CH=CH2}$. This appears to be a quite nice molecule that reacts evenly on both sides under polymerization. This material is also listed as photosensitive, which I interpret that it sheds something from both ends to activate the ends.
The other, of course is a mixture of three monomers: Butyl acrylate ($\ce{H2C=CH-CO-O-C4H9}$), methyl methacrylate ($\ce{H2C=C(CH3)-CO-O-CH3}$) and methacrylic acid ($\ce{H2C=C(CH3)-COOH}$). The first two have ester groups in them, the last has its precursor, the $\ce{-COOH}$ group (carboxylic acid). All these only seem to have one active side to me.
Assuming the four main chemicals are mixed somewhat evenly and in even numbers and what might be an ample supply of the starter Hydroxycyclohexyl-phenyl-ketone, they surely will react and polymerize under UV light of about 400 nm (+- 5), as this is how the mixture behaves in its native application, an SLA printer.
However I have a problem with these parts:
- What kind of reaction does happen between the compounds? I remember vaguely that some polymerizations create waste in the shape of water (was that condensation?), but I don't really see that happening here for most of the combinations and, as a result, I fail to see what the parts of the polymer might look like in their bonded state.
- What type of bonds does the resulting polymer have? This is pretty much the direct result of failing to see the reaction between the compounds. I thought I had seen a possibility to form an ester ($\ce{R_1-CO-O-R_2}$) between the methacrylic acid and the hexanediol diacrylate, but then realized the later misses an alcohol group ($\ce{R-OH}$) to attack and create water from to form the bond. So I am pretty sure that these don't bond as esters to one another, but what is the correct name for these bonds that elude me?!
- What would this polymer be classed as? I remember that some polymers are classed based on their monomers, manufacturing process, the chain length, bond type, and the macro-structure, putting each into several groups. These would allowing to estimate some vague properties about them. It's most certainly not a Homogenous one like pure PolyLacticAcid, as it is basically made up of 4 different monomers. It also should not form an elastic bond due to what I know from the MSDS and that the processed resin is a somewhat brittle product. But what groups it can be put into from the polymerization process?