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

Abstract

We have synthesized novel biobased and environmental friendly mid-chain functional macrophotoinitiators of poly(D,L-lactide) homopolymer (PDLLA-PI-PDLLA) and tetrablock poly(D,L-lactide)-poly(ε-caprolactone) copolymer (PDLLA-PCL-PI-PCL-PDLLA) with controlled molecular weights and narrow molecular weight distributions via ring-opening polymerization (ROP). Mid-chain functional poly(D,L-lactide) (PDLLA-PI-PDLLA) macrophotoinitiator was prepared by ROP of D,L-lactide (DLLA) monomer using a dihydroxy-functional photoinitiator (HO-PI-OH) as the initiator and stannous-2-ethyl hexanoate (Sn(Oct) 2 ) as the catalyst. Tetrablock poly(D,L-lactide)-poly(ε-caprolactone) copolymer (PDLLA-PCL-PI-PCL-PDLLA) with a mid-chain photofunctional group was synthesized via sequential ROP of ε-caprolactone and D,L-lactide using Sn(Oct) 2 as the catalyst. The resultant polymers were fully characterized by means of 1 H NMR, FTIR, UV-vis, Fluorescence, and GPC techniques. The obtained macrophotoinitiators were used as a prepolymer in photoinitiated free radical polymerization for obtaining AB-type diblock copolymer and ABC-type triblock terpolymer.

Facile catalytic ring opening polymerization of lactic acid: Comparing the performance of Fe and Zn metal species

“…Peaks appeared at 1,185 cm −1 and 1,198 cm −1 are addressed to COC bond vibration in lactic acid monomer and polylactide, respectively. As it was expected, the absorption peak of 936 cm −1 assigned to COO bond appeared in lactic acid monomer spectrum, has been disappeared in its corresponding polymer spectrum, implying successful transformation of lactic acid monomer to the PLA .…”

“…A reveal that peaks of 2,939 cm −1 and 3,000 cm −1 are relevant to the symmetric and asymmetric stretching of C‐H bond in the methyl group on PLA chain. The CO bond stretching peak has shifted from 1,735 cm −1 (lactate monomer) to 1,759 cm −1 in PLA . Moreover, a peak is observed at 1,458 cm −1 , which can be ascribed to bending of methyl group.…”

“…On the other hand, the nitrogen donor ligands with steric hindrance and metal‐nitrogen bond have low polarity and relatively nonpolar properties. First, TPPAA was chosen as nitrogen donor ligand, but the product had high‐molecular weight and low PDI, and polymerization reaction was long and needed a high temperature . Despite ongoing advances in developing aluminum‐based precursors, their toxicity has limited their usage in medical application.…”

Photopolymerization of acrylates by enzymatically synthesized PCL based macrophotoinitiator

“…In biomedical applications such as bone cements and tooth fillings, prepolymers which bear photoactive groups are injected to obtain complex forms through small holes which overcomes the drawbacks of the surgical operations [20]. Hindering unpleasant odors, providing better solubility and compatibility are also the encouraging factors for utilizing polymeric photoinitiators [11]. Poly(benzyl acrylate) (PBzA) was preferred in the literature due to its high thermal and photochemical stability and poly(tetrahydrofurfuryl acrylate) (PTHFA) was noted with its recognizable blood compatibility [21,22].…”

“…In the literature, benzoin, 2-hydroxy-2-methyl-1-phenyl propan-1-one (Darocure 1173), 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl propan-1-one (Irgacure 2959) photoinitiators were used in the synthesis of PCL based macrophotoinitiators via stannous octoate catalyzed living ring-opening polymerization (ROP) to induce photopolymerization of methyl methacrylate (MMA) resulting in block copolymers of ɛ-caprolactone (CL) and MMA [10]. Similarly, mid-chain macrophotoinitiators comprised of poly (D,L-lactide) homopolymer and tetrablock poly(D,Llactide)-poly(ε-caprolactone) copolymers were synthesized via ROP and they were utilized in further installation of MMA units via light induced polymerization [11]. Nucleophiles such as water and alcohols were studied in the literature for their initiation efficiency in eROP of lactones.…”