Biodegradable Cellulose Diacetate-graft-poly(l-lactide)s:  Enzymatic Hydrolysis Behavior and Surface Morphological Characterization

Abstract

Enzymatic hydrolysis of selected copolymers of cellulose diacetate-graft-poly(L-lactide)s (CDA-g-PLLAs) were conducted with proteinase K for film specimens, which were solely quenched from the molten state or, further, annealed at temperatures below or above their glass transition temperatures. The hydrolysis rates depended seriously on the thermal history, as well as on the graft modification. Especially, the heat treatment, followed by physical aging or crystallization of the originally amorphous materials, was a key factor to control subtly their enzymatic degradation behavior. Atomic force microscopy revealed that the enzymatic hydrolysis transformed the surface of the respective films into a more undulated one with a number of fine protuberances, for example, of several hundred nanometers in height and a few micrometers in width. Attenuated total reflection FTIR spectroscopy ensured selective release of lactyl units from the surface region. In visual appearance, some degraded films exhibited even an iridescent color due to an effect of interference of visible light reflected on the surface. These observations suggest a conception of "spatiotemporally controlled degradation", leading to a new method not only for regulation of the overall rate of degradation but also for fine surface abrasion of polymer materials.

Estimation of Miscibility and Interaction for Cellulose Acetate and Butyrate Blends with N‐Vinylpyrrolidone Copolymers

“…These plasticizers are, however, prone to bleed out from the molded CA products more or less in the course of time. In order to remedy the drawback, the authors' attention has been paid to two potential methods; one is graft copolymerization of CA with biodegradable aliphatic polyesters, [5][6][7][8] and the other is compatibly blending CA with flexible polymers as a polymeric plasticizer. [9][10][11][12] Polymer/polymer blending is a well-established, useful method to improve the original physical properties of one or both of the components, or to design new polymeric materials exhibiting wide-ranging properties and/or synergistic functions without parallel in single polymers and in the gross mechanical mixture.…”

Cellulose Acetate‐graft‐Poly(hydroxyalkanoate)s: Synthesis and Dependence of the Thermal Properties on Copolymer Composition

“…[3] Following this, we proposed a new concept, ''spatiotemporally controlled degradation'', as a means of functionalizing biodegradable polymers, through controlling not only the biodegradation rate but also the surface morphology and composition for enzymatically hydrolyzable CA-g-PLLA films. [4] In view of those results, this type of graft copolymerization may be adoptable for other compounds which are polymerizable at hydroxyl positions. Such compounds include some aliphatic lactones, conventionally exemplified by (R,S)-b-butyrolactone (BL), d-valerolactone (VL) and e-caprolactone (CL).…”

Crystallization Behavior of Poly(ε‐caprolactone) Grafted onto Cellulose Alkyl Esters: Effects of Copolymer Composition and Intercomponent Miscibility

“…[11] Especially for a CA-g-poly(L-lactic acid) series, Teramoto and Nishio [12] examined in detail the supramolecular structure development via quantitative estimations of physical aging and crystallization phenomena, in relation to the enzymatic degradation behavior. [9] In this extensional study, the graft copolymerization of e-caprolactone (CL) was applied to CA and CB, their acyl DS ranging from 2.1 to more than 2.9. For selected CA-g-PCL and CB-g-PCL samples, all having a PCL-rich copolymer composition, a special interest was focused on the meltcrystallization of PCL side-chains accompanied by the formation of spherulites.…”