Solid‐State ¹³C‐NMR detection of the isotropic carbonyl line shape in blends of poly(vinylphenol) with main‐chain polyesters

Abstract

The solid‐state NMR isotropic line shape of the carbonyl 13C resonance is useful as a qualitative diagnostic probe of the polyester component′s morphology and molecular mobility in partially miscible blends with poly(vinylphenol), PVPh. The main‐chain polyesters chosen for investigation in this study are poly(ethylene succinate), poly(ethylene adipate), poly(butylene adipate), and poly(caprolactone). A crystalline phase exists for polyester‐rich mixtures in all cases. Verification of this claim is provided by DSC endothermic tran‐sitions that map out melting point depression in the temperature‐composition phase dia‐grams. The carbonyl 13C‐NMR signal in the crystalline domains exhibits a full width at half height of 1–2 ppm when the glass transition temperature of the blends is below the temperature of the NMR experiment. In all cases, a single concentration‐dependent glass‐transition temperature is measured by DSC, which increases monotonically from below ambient for polyester‐rich blends to well above ambient for blends that are rich in poly(vinylphenol). When the concentration of the amorphous proton donor PVPh is suf‐ficient to thwart crystallization of the polyester and increase the glass transition temperature of the blends above the temperature of the NMR experiment, the line width of the carbonyl resonance increases three‐ to fourfold to ca. 5–6 ppm. When the blends are completely amorphous and Tg is above ambient, the polyester carbonyl 13C line shape reveals at least two morphologically inequivalent microenvironments. A partially resolved carbonyl signal in rigid amorphous blends is (a) identified at higher chemical shift relative to the crystalline component, and (b) attributed to hydrogen bonding in the amorphous phase. This inter‐action‐sensitive hydrogen‐bonded carbonyl signal accounts for an increasing fraction of the overall NMR absorption envelope of the carbonyl carbon site when the polyester is saturated with PVPh. The main‐chain polyesters were chosen to probe the effect of chemical structure of the proton acceptor on the potential for hydrogen‐bond formation. Aliphatic CH2 spacers between the carbonyl groups dilute the concentration of interacting sites, and the dependence of the carbonyl 13C‐NMR line shape on blend concentration reveals unique spectroscopic behavior in each of the four blend systems investigated. © 1993 John Wiley & Sons, Inc.

Miscibility and phase behavior of poly(D,L-lactide)/poly(p-vinylphenol) blends

“…Unlike blends of PVPh with various polyesters where specific intermolecular hydrogen-bonding interactions are effective, 19,[22][23][24] there is no such interaction in the PDLLA/PVPh blends. Polymers such as poly(vinyl chloride), 4 poly(hydroxyether of bisphenol-A), 3 polyepichlorohydrin 29 are miscible with aliphatic polyesters having suitable CH x /COO ratios.…”

“…17,18 Due to the lack of specific interactions, most of these blends are immiscible. Poly(p-vinylphenol) (PVPh) has been found to be miscible or partially miscible with polyacrylates, 19 polymethacrylates, 20,21 and polyesters 19,[22][23][24] on the basis of specific hydrogen-bonding interactions. It has also been found that the interassociation between polymers is affected by the structure of estercontaining polymers.…”

“…These polymers are immiscible with a polyester that has a large or a small CH x /COO ratio. PVPh is miscible with several polyesters such as PPL, 19 PCL, 19 PHB, 22,23 poly-(ethylene succinate) 24 (PES), poly(ethylene adipate), 24 and poly(butylene adipate). 24 It is of interest to note that PVPh is miscible with PES but not with PDLLA, even though both polyesters have the same CH x /COO ratio of 2.…”

Effect of pH on the physico-mechanical properties and miscibility of methyl cellulose/poly(acrylic acid) blends

“…In addition, PVPh can also form miscible blends with some aliphatic polyesters (Belfiore, Qin, Ueda, & Pires, 1993;Xing, Dong, An, Feng, Avella, & Martuscelli, 1997;Woo & Chiang, 2004) [e.g., poly(-caprolactone) (PCL), poly(ethylene succinate) (PES), poly(ethylene adipate) (PEA), and poly(␤-hydroxybutyrate) (PHB)], or with some aromatic polyesters (Nurkeeva et al, 2000) [e.g., poly(ethylene terephthalate) (PET), poly(butylene terephthalate) (PBT) and poly(ethylene 2,6-naphthalenedicarboxylate) (PEN)].…”

Miscibility and specific interactions in polyacrylonitrile/ poly(p-vinylphenol) blends

“…The hydroxyl groups of PVPh are capable of undergoing intermolecular interactions with proton-accepting functional groups. As a result of such interactions, PVPh is miscible with a large variety of polymers, including polymethacrylates [1][2][3][4][5] , polyacrylates 6) , polyesters [7][8][9][10][11] , polyitaconates 12,13) , polyamides 14) , polyethers 7,15,16) , etheric polyphosphazenes 17) and polyketones 18) . In contrast, not many miscible blends of polyacrylonitrile (PAN) have been reported.…”