Enzymatic degradation of hyperbranched polyesters

Abstract

In this work, the enzyme-catalyzed degradation of hyperbranched polyesters (HBPEs) was investigated. Enzymatic degradation experiments were performed in a phosphate buffer in the presence of the lipases Candida cylindracea, Pseudomonas cepacia, Novozym 388, Amano CE, Lipomod 34P, and Cal-B, whereas control experiments were performed in the same system without lipases. The extent of polymer degradation was determined by quantification of the released free fatty acids by gas chromatography. The influence of the alkane chain length and the number of alkane chain end groups on the lipase-catalyzed hydrolysis of esterified HBPEs was investigated systematically. It was found that the increase in the alkane chain length of the end groups diminished the enzymatic degradation of the polymer, whereas the number of end groups had no influence on the degradation rate. The effect of temperature on the rate of degradation was also described. Surface morphological changes that occurred during the degradation were assessed with reflected electron microscopy. The changes in the crystallinity of the polymers after they were subjected to degradation were qualitatively determined with differential scanning calorimetry through the quantification of the enthalpy of melting. The enthalpy of melting of one HBPE sample increased from 79 to 90 and 94 J/g with and without the action of Lipomod 34P, respectively, in 7 days, showing the changes in the crystallinity of the polymer. The results prove that modified HBPEs are an important new class of biodegradable materials with a predictable degradation mechanism, and the degradation can be adjusted on the basis of the molecular engineering.

Hyperbranched polyglycerol as an additive for water-based printing ink

“…The color of the paper strip, quantified on a gray scale (1)(2)(3)(4)(5), increases with the number of rub cycles. The overprinted oPP films showed slightly better colorfastness to rubbing than the overprinted PET films, which was expected, because the adhesion of the printing ink to oPP was slightly better.…”

“…Hyperbranched polymers exhibit unique chemical and physical properties. [4][5][6][7][8] The properties of hyperbranched polymers are often affected by the structure and architecture of the macromolecule, in terms of backbone and functional end-groups, degree of branching, molecular-weight distribution and so forth. Nowadays, the most popular hyperbranched polymers are hyperbranched polymers terminated with hydroxyl groups, such as polyethers (based on glycidol, i.e., polyglycerol) and polyesters (based on 2,2-bis(hydroxymethyl)propionic acid, i.e., Boltorn TM ).…”

Measurements of mass-fraction activity coefficient at infinite dilution of aliphatic and aromatic hydrocarbons, thiophene, alcohols, water, ethers, and ketones in hyperbranched polymer, Boltorn H2004, using inverse gas chromatography

“…For instance, it has been shown that branched polymers are promising candidates for gas absorbents with a high capacity for CO 2 and with large selectivities [5]. Polyester materials have been recognized as the most promising family of HBP, much due to unique properties such as high functional group density with a wide range of substituents, biocompatibility, biodegradability, non-toxicity, high solubility (sometimes even in water) as well as storage stability [10,11]. Water soluble HBP was synthesized for drug delivery applications [11,12].…”

Drug dispersion degree and drug dissolution rate in Hybrane S1200-based instant-release matricial particles prepared by hot melt extrusion

“…As HME, hyperbranched polymers (HPs) have received increasing attention throughout the last few years in the pharmaceutical field due to its attractive properties as non-toxicity and biocompatibility 19 . HPs are dendritic polymers that, different to dendrimers which are structurally perfect, present disordered branching and therefore lack of structural perfection.…”