Język Polski
English
Published
: 2022-09-19
Macro-azo-initiators having cinnamate end groups: synthesis, characterization and photopolymerization with 2-hydroxyethyl methacrylate
Abstract
Three macro-azo-initiators (MAI, M" = 1583, 4520, 8427) prepared (after [10]) by reacting polyethylene oxide) (PEO, Mn = 600, 2000, and 4000) with AIBN (2:1 by mole), were modified by esterification with cinnamoyl chloride to replace the original hydroxyl end-groups by the cinnamate end-groups. The MAI were vised as initiators (2-10 wt. % based on monomer weight) in photoinitiated (UV quartz tube, 37.5 W, distance 20 cm) polymerization of 2-hydroxyethyl methacrylate (HEMA) coupled with photocrosslinking (Scheme I). The structures suggested for the MAI oligo-mers were confirmed in terms of FTIR and 'H-NMR spectra (Figs. 1, 2). Photocrosslinking was monitored at 282 nm; as the irradiation time was protracted, the absorbance fell (Fig. 3). For the three MAI examined, cross-linking percentage was studied in relation to irradiation time; crosslinking rates were highest within the first 2-4 min (Fig. 4); in 20 min, the cinnamate groups participated in 77-82% in the crosslinking (Fig. 4). The conversion of photosensitive groups (-CH=CH-) was not related to the M of MAI. A DSC thermogram for MAI-2000 (Fig. 5) exhibited an endotherm at 54°C (melting of PEO crystal phase) and a broad exotherm at 90-137°C (decompn. of azo groups). Photocrosslinked PHEMA prepared with MAI-2000 having cinnamate end-groups attained the equilibrium degree of swelling (in deionized H2O) in 20 h (Fig. 6). The swelling degree rose as the amount of MAI used was raised, presumably on account of the rising content of polyoxide segments; it also rose as the Mn of the modified MAI was increased (Fig. 7).
Details
Statistics
Authors
Download files
Zasady cytowania
Jantas, R., Wódka, T., & Janowska, G. (2022). Macro-azo-initiators having cinnamate end groups: synthesis, characterization and photopolymerization with 2-hydroxyethyl methacrylate. Polimery, 46(11-12), 812–816. Retrieved from https://polimery.ichp.vot.pl/index.php/p/article/view/2137
