Hello, I'm trying to use an NMR spectrum to define/calculate a "degree of acrylation" for a PLA-PEG-PLA block copolymer that is di-acrylated. The macromer or (macro-monomer) is symmetrical in nature and looks like this:

**(Acr)p-(PLA)x-(PEG)m-(PLA)x-(Acr)p**

(-CH2-CH-CO-)*p*-(O-CH[CH3]-CO-)*x*-(CH2-CH2-O-)*m*-(O-CH[CH3]-CO-)x-(-CH2-CH-CO)*p*

For the PEG block in the middle, *m* is large (I have 4 different samples with pre-defined PEG MWs of 2k, 4k, 8k, and 12k g/mol). For the PLA blocks on either side of the PEG block, I have been able to calculate the average values of *x* for each sample, using the known value of *m* for the PEG blocks and the NMR-integrated ratio of **PLA CH peaks** (at **5.2 ppm**) to **the main-chain PEG CH2 peaks** (at **3.6 ppm**). So the formula set-up for that looks like this:

*m* = (PEG MW) / (EG unit MW)

2*x* / *m* = PLA CH peak / PEG CH2 peak

*x* is typically small (*x* = 2 - 6 LA units per chain end).

~~Using two other peaks, ~~In order to calculate the average value of *p* and thereby define a "degree of acrylation," I should be able to ~~do something ~~use a similar ~~to calculate the average value of ~~*p* and thereby define a "degree of acrylation." So process. Presumably, by integrating the three **acrylate peaks** (~ **6 ppm**) compared to a shifted PEG peak that represents the **PEG CH2 groups directly next to the PLA blocks** (~ **4.3 ppm**). However, I have a few questions:

1) Why do the acrylate groups gives 3 peaks even though they only contain two ~~follow-up questions:~~types of hydrogens (CH2 and CH)?

2) Is it correct to assume that the combined integration of the acrylate peaks proportionally represent (2H+1H) x 2 end groups = 6H's?

3) Would it be correct, assuming there are two PEG CH2 groups next to PLA blocks, per chain, that the peak at 4.3 proportionally represents 4 H's?

4) Since the desire in synthesizing these macromers is to obtain *p* = 1 (an average of one acrylate group per chain end) then does it make sense if I just define the "degree of acrylation" as *p*/1?

5) To calculate *p* using the NMR peaks: This is supposed to be possible by integrating the three **acrylate peaks** (~ **6 ppm**) compared to a shifted PEG peak that represents the **PEG CH2 groups directly next to the PLA blocks** (~ **4.3 ppm**). Since there are 2 such CH2 groups per chain as well as 2 acrylate groups per chain, would the ratio of the two peaks directly give me the value of *p*? For instance, if *t* refers to the number of CH2 groups per chain located directly next to PLA blocks, then using a formula similar to that above:

2*p* / *t* = Acr group peaks / shifted PEG CH2 group peak

Since we know *t* = 2, then I can directly calculate *p*?