Table 2. 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	M n (GPC)g	M n (calcd)/Mn (GPC)	M w/Mng	Conv (%)
PEG200		—	—	4.5	200	214
PCL-b-PEG200-b-PCL5	PEG200	28	5	4.9	780	770	1410	0.55	1.18	92
PCL-b-PEG200-b-PCL10	PEG200	14	10	11.5	1350	1530	3145	0.42	1.24	95
PCL-b-PEG200-b-PCL15	PEG200	11	15	14.3	1990	1850	3988	0.49	1.22	98
PCL-b-PEG200-b-PCL20	PEG200	8	20	21.0	2440	2610	5628	0.43	1.24	98
PTHF250		—	—	3.3	250	254
PCL-b-PTHF250-b-PCL5	PTHF250	28	5	5.6	820	890	1601	0.51	1.19	96
PCL-b-PTHF250-b-PCL10	PTHF250	16	10	11.4	1390	1560	3273	0.42	1.23	97
PCL-b-PTHF250-b-PCL15	PTHF250	12	15	16.2	1960	2100	4853	0.40	1.16	99
PCL-b-PTHF250-b-PCL20	PTHF250	10	20	20.3	2530	2570	5483	0.46	1.40	99
PPG425		—	—	6.8	425	396
PCL-b-PPG425-b-PCL5	PPG425	43	5	7.8	1000	1280	2373	0.42	1.15	89
PCL-b-PPG425-b-PCL10	PPG425	27	10	14.2	1570	2020	4102	0.38	1.16	96
PCL-b-PPG425-b-PCL15	PPG425	20	15	18.7	2130	2530	6079	0.35	1.14	98
PCL-b-PPG425-b-PCL20	PPG425	16	20	22.7	2680	2980	5719	0.46	1.48	98

^aObtained from the equation % ether = (MW_initiator/M_n(NMR)) × 100; where MW_initiator is the molecular weight of initiator (HOPEGOH, HOPTHFOH, or HOPPGOH).

^bDetermined by ¹H NMR in CDCl₃.

^cObtained from CL/polyether feed molar ratio.

^dUsing end-group analysis by ¹H NMR.

^eObtained from the equation M_n(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 (HOPEGOH, HOPTHFOH, or HOPPGOH).

^fObtained from the equation M_n(NMR) = (DP(NMR) × MW(repetitive unit)) + MW(polyether), where MW is the molecular weight of the repetitive unit (114 g mol⁻¹) or initiator (HOPEGOH, HOPTHFOH, or HOPPGOH).

^gDetermined by gel permeation chromatography (GPC) using polystyrene standards.