Convenient Access to α‐Amino‐ω‐Hydroxyl Heterobifunctional peg and ppo via a Sacrificial Hexahydro‐Triazine Star Strategy

Figure 1.  SEC (DMF, PEG-calibration) TrAz-PEG polymers (full lines) with the corresponding hydrolyzed 

α-amino-ω-hydroxyl PEG (dashed lines) (A), 

1

H NMR (400 MHz, C

6

D

6

) of TrAz initiated star polymer TrAz-PEG

61

 (B) and the corresponding hydrolyzed 

α-amino-ω-hydroxyl NH

2

-PEG

25

-OH (C).

Table 1.  Characterization data for synthesized star polymers and hydrolyzed linear products.

Sample

Before hydrolysis

After hydrolysis

M

n

target

  

[g mol

−1

]

M

n

 (

1

H-NMR)  

[g mol

−1

]

M

n

 (SEC)  

[g mol

−1

]

Đ (SEC)

M

n

 (SEC)  

[g mol

−1

]

Đ (SEC)

TrAz-PEG

61

   3200

   2900

   2600

1.07

 700

1.07

TrAz-PEG

142

   6300

   6500

   5100

1.07

1600

1.05

TrAz-PEG

360

15 800

16 000

11 100

1.10

3800

1.05

TrAz-PPO

47

   3100

   2900

   2300

1.04

 700

1.07

TrAz-PPO

85

   6000

   5100

   3900

1.04

1300

1.06

TrAz-PPO

101

   8900

   6100

   4600

1.05

1500

1.06

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of 1–5 kg mol

−1

, showing narrow molecular weight distribu-

tions with Đ 

< 1.1. Furthermore, the star polymers could be 

directly used as a polyol component in the synthesis of PUs. 

As demonstrated, the synthesized PU elastomer was rapidly 

degraded under acidic conditions. This approach may enable 

recycling or reprocessing.

The use of aminal protected amine groups in the AROP 

expands the scope of protecting groups for amino groups. This 

approach that relies on the synthesis of an acid labile, sacrifi-

cial polyether star polymers represents a simple and inexpen-

sive route to 

α-amino-ω-hydroxyl heterobifunctional polyethers. 

These compounds are useful for PEGylation or surface modi-

fication applications, since the amino group can be addressed 

in a highly selective manner by a variety of transformations. 

Finally, we emphasize that the strategy outlined here translates 

to merely one single “CH

2

” moiety as a protecting group per 

amino-group (and per polymer chain), which renders it highly 

atom-economical. In this regard, the approach is superior to 

established protecting group strategies.