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. 2025 Nov 7;15(51):43405–43420. doi: 10.1039/d5ra06419h

Table 3. Thermal properties of triblock copolymers (PCL-b-B-b-PCL) prepared using different polyethers as central segment (B = PEG, PTHF and PPG of different molecular weight) as initiators in the ROP of CL.

Sample Initiator Ether (%)a,b DP (calcd)c DP (NMR)b,d M n (calcd)e M n (NMR)b,f T c (°C)g ΔHc (J g−1)g T mPCL (°C)h ΔHm (J g−1)h x i (%)h,i
PEG200 — — 4.5 200 214 −50j — —
PCL-b-PEG200-b-PCL5 PEG200 28 5 4.9 780 770 — — 6 0.7 0.5
PCL-b-PEG200-b-PCL10 PEG200 14 10 11.5 1350 1530 15 50 32,41 50 37
PCL-b-PEG200-b-PCL15 PEG200 11 15 14.3 1990 1850 20 73 35,42 76 56
PCL-b-PEG200-b-PCL20 PEG200 8 20 21.0 2440 2610 23 75 43,48 77 57
PTHF250 — — 3.3 250 254 −16 53
PCL-b-PTHF250-b-PCL5 PTHF250 28 5 5.6 820 890 −18 42 −16k,5,13 43(31m) 23
PCL-b-PTHF250-b-PCL10 PTHF250 16 10 11.4 1390 1560 18 61 33,41 63 46
PCL-b-PTHF250-b-PCL15 PTHF250 12 15 16.2 1960 2100 18 70 39,41 74 54
PCL-b-PTHF250-b-PCL20 PTHF250 10 20 20.3 2530 2570 22 65 41,47 72 53
PPG425 — — 6.8 425 396 −71l — —
PCL-b-PPG425-b-PCL5 PPG425 43 5 7.8 1000 1280 −15 37 2,20 33 24
PCL-b-PPG425-b-PCL10 PPG425 27 10 14.2 1570 2020 11 57 28,39 56 41
PCL-b-PPG425-b-PCL15 PPG425 20 15 18.7 2130 2530 18 62 38,45 62 45
PCL-b-PPG425-b-PCL20 PPG425 16 20 22.7 2680 2980 20 60 40,48 61 45
a

Obtained from % ether = (MWinitiator/Mn(NMR)) × 100; where MWinitiator is the molecular weight of initiator (HOPEGOH, HOPTHFOH, or HOPPGOH).

b

Determined by 1H NMR in CDCl3

c

Obtained from CL/polyether feed molar ratio.

d

Using end-group analysis by 1H NMR.

e

Obtained from the equation Mn(calcd) = (MW(CL))·(mmol CL/mmol polyether) + MW(polyether), where MW is the molecular weight of ε-caprolactone (CL, 114 g mol−1) monomer or initiator.

f

Obtained from Mn(NMR) = (DP(NMR) × MW(repetitive unit)) + MW(polyether).

g

Obtained by DSC analysis (first cooling).

h

Obtained by DSC analysis (second heating).

i

Using the value of 135.3 J g−1 for a PCL 100% crystalline,68 the crystallinity of PCL (xPCL) was calculated.

j

Reported value for PEG (Mn = 200 g mol−1), liquid at room temperature.70

k

T m of the PTHF segment.

l

Reported value for PPG (Mn = 425 g mol−1), liquid at room temperature.71

m

Enthalpy of fusion attributed to the PCL, obtained by the equation ΔHmPCL = (ΔHm) × (weight fraction of PCL).