Synthesis of mid-chain functional macrophotoinitiators of poly(D,L-lactide) homopolymer and tetrablock poly(D,L-lactide)-poly(ε-caprolactone) copolymer by ring-opening polymerization

Figures & data

Table 1. Synthesis of homo PDLLA-PI-PDLLA^a and tetrablock PDLLA-PCL-PI-PCL-PDLLA^b macrophotoinitiators.

Run	Initiator (I)	[M]/[I]	Time (h)	Macrophotoinitiator	Yield (%)	Mn theo	Mn H NMR^c	Mn GPC^f	Mw/Mn
1	HO-PI-OH	20	2	PDLLA-PI-PDLLA	82	2590	2750	2300	1.18
2	HO-PI-OH	40	1	PDLLA-PI-PDLLA	76	4600	4660	4500	1.22
3	PCL-PI-PCL^d	40	6	PDLLA-PCL-PI-PCL-PDLLA	80	9410	9610^e	10,200	1.34

^a Prepared by ROP of D,L-lactide (DLLA) in bulk at 130 °C, the mol ratio of [HO-PI-OH]/[Sn(Oct)₂] = 134/1.

^b Prepared by ROP of D,L-lactide (DLLA) in bulk at 130 °C in the presence of PCL-PI-PCL as macroinitiator, the mol ratio of [PCL-PI-PCL]/[Sn(Oct)₂] = 134/1.

^c Calculated from ¹H NMR measurements.

^d Prepared under the same conditions given in Ref. [13]. (Yield: 100%, M_{n theo} = 4800, M_{n H NMR} = 5000, M_{n GPC} = 4600 M_w/M_n = 1.36).

^e M_{n H NMR} = DP_PDLLA× 144.13 + M_{n PCL-PI-PCL}. Degree of polymerization for PDLLA segments was calculated from ¹H NMR, using the formula; DP_PDLLA = I_PDLLA/I_PCL× DP_PCL.

^f Determined by GPC according PSt standards using correction factor X, 0.58 for the macrophotoinitiators.

Figure 1. ¹H NMR spectra of PDLLA-PI-PDLLA (a) and PDLLA-PCL-PI-PCL-PDLLA (b) macrophotoinitiators in CDCl₃.

Figure 2. GPC traces of PDLLA-PI-PDLLA (Table 1, Run 1) (a), and PDLLA-PCL-PI-PCL-PDLLA (Table 1, Run 3) (b), macrophotoinitiators, and PDLLA-PMMA diblock copolymer (c), and PDLLA-PCL-PMMA triblock terpolymer (d).

Figure 3. UV absorption spectra of PDLLA-PI-PDLLA (0.88 g L⁻¹) and PDLLA-PCL-PI-PCL-PDLLA (1.00 g L⁻¹) macrophotoinitiators in CH₂Cl₂.

Figure 4. Fluorescence spectra of PDLLA-PI-PDLLA (0.51 g L⁻¹) and PDLLA-PCL-PI-PCL-PDLLA (1.00 g L⁻¹) macrophotoinitiators in CH₂Cl₂, λ_exc = 325 nm.

Figure 5. ¹H NMR spectrum of PCL-PDLLA-PMMA triblock terpolymer in CDCl_3.

Scheme 1. Synthesis of PDLLA-PI-PDLLA.

Scheme 2. Synthesis of PDLLA-PCL-PI-PCL-PDLLA.

Scheme 3. Synthesis of diblock copolymers and triblock terpolymers.

Degirmenci M, Hizal G, Yagci Y. Synthesis and characterization of macrophotoinitiators of poly(ε-caprolactone) and their use in block copolymerization. Macromolecules. 2002;35:8265–8270.10.1021/ma020668t

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