Spectroscopic and Morphology Studies of Biodegradable Nanolamellar Lactone Based Triblocks

Abstract

Spectroscopic and morphological analysis of a series of lactone based triblock copolymer was undertaken. In the synthesized triblocks, the middle segment was γ-valerolactone, δ-valerolactone or ε-caprolactone (5-7 membered rings), while D, L-lactide, cis-lactide or glycolide was taken as the terminal segment. The specific signals of 1 H NMR were shifted depending on the type of monomers present in the copolymer and a peak at 4.3 ppm validated chain extension on addition of the terminal block. In 13 C NMR, a sharp peak around 173 ppm and a comparatively low intense peak around 168 ppm due to carbonyl region confirmed the block architecture. The peaks for O-(C=O), O-CH 2 , C=O and C-O-C stretching showed characteristic shift in FTIR on copolymerization. The presence of different blocks as middle segment and terminal segment was confirmed from CH/CH 3 stretching and νC-COO stretching regions in Raman spectra. The wide angle X-ray diffractograms indicated the presence of crystalline domains in the copolymer, but the peak position and intensity were altered as a synergistic effect of crystallographic nature and fraction of the block incorporated in the triblock.The glass transition temperature shifted accordingly. Atomic force microscopy and transmission electron microscopy analysis confirmed the formation of nanolamellar structure. The lamellar spacing (10-15 nm) calculated from Small angle X-ray scattering correlated well with that obtained from atomic force microscopy. Long range array of nanofibrills was retained in triblock having ε-caprolactone, which was disturbed for δ-valerolactone based triblocks.

Stimuli‐responsive polyurethane bionanocomposites of poly(ethylene glycol)/poly(ε‐caprolactone) and [poly(ε‐caprolactone)‐grafted‐] cellulose nanocrystals

“…The peak in the δ = 5.0 − 5.3 ppm region is the identity of PCL as a polyester, which in the case of grafting PCL onto CNC causes a shift to lower chemical shift ( δ = 4.0 − 4.2 ppm). This large chemical shift of OCH hydrogen is due to deshielding effect of the electronegative oxygen attached to the carbon and has four splitted peaks due to methyl group attached to it (OCH [CH3]) 18 . The relative integration of the peaks available at chemical shifts of δ = 1.675 and 1.385 ppm gives the molecular weight of the grafted chains being equal to 1935 D for the PCL chain graft.…”

Raman and NMR Spectroscopic Studies on Hydrolytic Degradation of d,l-Lactide−δ-Valerolactone–d,l-Lactide Copolymer

“…25,26 Their chemical structure and molecular weight are given in Table 1. Sodium dihydrogen phosphate, disodium hydrogen phosphate, sodium chloride, and potassium chloride for buffer preparation were obtained from Merck (Germany).…”

“…The polymers DLL 17 DV 66 DLL 17 , DLL 10 DV 80 DLL 10 , DLL 17 EC 66 DLL 17 , GL 17 DV 66 GL 17 , and CL 17 DV 66 CL 17 were prepared by ring opening polymerization as reported previously. , Their chemical structure and molecular weight are given in Table . Sodium dihydrogen phosphate, disodium hydrogen phosphate, sodium chloride, and potassium chloride for buffer preparation were obtained from Merck (Germany).…”

“…Recently, we synthesized and characterized a series of terpolymers (BAB) from δ-valerolactone (A), d , l -lactide (B), ε-caprolactone (A), glycolide (B), and cis-lactide (B). , This paper deals with the hydrolytic degradation of these terpolymers to establish their acceptability as a drug delivery system. Herein, their degradation with respect to time and composition variation is evaluated.…”