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Biodegradable polymer–photosensitizer composites were developed, which is suppressed biodegradation due to bactericidal activity under light irradiation but proceeds under dark conditions. The composites exhibited antibacterial activity under light irradiation, which was attributed to the generation of singlet oxygen (1O2). Biodegradation was evaluated in seawater using the biochemical oxygen demand (BOD) method. In the dark, the composite and base polymer biodegraded to a similar degree. However, under light irradiation, the biodegradation of the composite was suppressed. In field tests, the rate of volume reduction of the composites decreased under illumination. The main cause of the suppression of biodegradation is suggested to be due to the decrease in the number of bacteria on the surface of the material and the inactivation of exoenzymes. The findings are expected to contribute to the development of biodegradable polymers that do not biodegrade during use but only when disposed of in the environment, thereby achieving on-demand degradation.

Atactic poly[(R,S)-3-hydroxybutanoic acid] with varying enantiomer ratios was synthesized using a combination of renewable (R)-3-hydroxybutanoic acid and its racemic mixture. The melting temperature of the synthesized atactic polymers was consistently lower than that of poly[(R)-3-hydroxybutanoic acid], exhibiting a decreasing trend with an increasing enantiomer ratio. The biodegradability of the synthesized polymers was assessed through enzymatic and seawater degradation studies.Graphical AbstractAtactic poly[(R,S)-3-hydroxybutanoic acid] with varying enantiomer ratios was synthesized using a combination of renewable (R)-3-hydroxybutanoic acid and its racemic mixture. The melting temperature of synthesized atactic polymers was consistently lower than that of poly[(R)-3-hydroxybutanoic acid], exhibiting a decreasing trend with an increasing enantiomer ratio. The biodegradability of the synthesized polymers was evaluated using an enzyme and seawater.

Plastics contribute to several industrial activities, but they also cause environmental pollution. Additionally, they rely on an ever‐decreasing supply of natural, but non‐renewable, resources. Such plastics should be replaced by materials that are biodegradable and made from renewable resources such as polymers. They are synthesized from plant‐derived (R)‐3‐hydroxybutyric acid and l‐lactic acid meet these requirements. Most of the synthesized poly((R)‐3‐hydroxybutyrate‐co‐l‐lactate) with various monomer composition ratios were degraded by enzymes (PHB depolymerase or Proteinase K). Evaluation of biodegradability in activated sludge showed that copolymers with 80% or less of l‐lactic acid units were degraded. Biodegradable plastics synthesized from chiral organic acids have the potential to replace petroleum‐based plastics. Poly[(R)‐3‐hydroxybutyric acid] is highly biodegradable, but have poor thermal properties. Copolymerization of (R)‐3‐hydroxybutyric acid with l‐lactic acid as monomers improved the thermal properties while maintaining its excellent biodegradability. Copolymers with a high (R)‐3‐hydroxybutyric acid unit ratio degraded well in activated sludge.

4‐Aminobutylic acid (GABA) is a monomer of plastic polyamide 4. Bio‐based polyamide 4 can be produced by using GABA obtained from biomass. The production of L‐glutamic acid (Glu) from biomass has been established. GABA is produced by decarboxylation of Glu in biological process. High‐performance liquid chromatography (HPLC) with derivatization is generally used to determine the concentration of GABA and Glu in reacted solution samples for the efficient production of GABA. In this study, we have investigated the rapid determination of GABA and Glu by capillary electrophoresis‐mass spectrometry (CE‐MS) without derivatization. The determination was achieved with the use of a shortened capillary, a new internal standard for GABA, and optimization of sheath liquid composition. Determined concentrations of GABA and Glu by CE‐MS were compared with those by pre‐column derivatization HPLC with phenylisothiocyanate. The determined values by CE‐MS were close to those by HPLC with pre‐column derivatization. These results suggest that the determination of GABA and Glu in reacted solution is rapid and simplified by the use of CE‐MS.

To make starch/polycaprolactone (PCL) blend with high miscibility, starch was chlorinated (starch-Cl) by using methanesulfonylchloride (CH3SO2Cl) in dimethylformamide (DMF) prior to blending. Starch-Cl/PCL blends were prepared by the mixing between starch-Cl and PCL solutions under various conditions. To study the change of structure, thermal and physical characteristics of starch-Cl/PCL blend, FTIR, DSC, SEM, and solvent resistance were measured. By blending starch-Cl and PCL, a chemical reaction occurred partially in blend (FTIR result); thereby, the miscibility (DSC and SEM results) and solvent resistance were increased. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1716–1723, 2004

Poly(ethylene terephthalate), PET reacted with various glycols in the presence of titanium tetraisopropoxide as a catalyst. The glycolyzed PET was fractionated into two parts—soluble and insoluble in CHCl3—characterized and used as a raw material to synthesize copolyesters. The soluble part in the CHCl3part was a mixture of monomers and oligomers, and no melting points were observed. On the other hand, in the insoluble part a melting point was determined. The glycolyzed PET and copoly(succinic anhydride/ethylene oxide), PES were condensed to produce copolymers. The synthesized copolyesters were amorphous and hydrolyzed enzymatically due to a decrease in the crystallinity. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1838–1847, 2002; DOI 10.1002/app.10462

The synthesis, characterization, hydrolysis and biodegradation of a copoly(ester amide), poly[acrylamide-co-(ɛ-caprolactone)], are described. The hydrogen transfer copolymerization of acrylamide (AA) with ɛ-caprolactone (CLN) in the presence of butyllithium or calcium hydride as initiators has been investigated. The calcium hydride was effective for the synthesis of the copoly(ester amide) in a wide range of polymer composition (AA/CLN =  10 : 90 to 90 : 10). The copoly(ester amide) was readily hydrolyzed in the presence of hydrochloric acid (0.1 n) at 125°C in an autoclave (e. g. AA/CLN =  59 : 41, degradation 93%). Furthermore, the copoly(ester amide) was hydrolyzed enzymatically by lipase from Rhizopus arrhizus. The behavior of the enzymatic hydrolysis differed to the non-enzymatic hydrolysis. The enzymatic hydrolyzability was remarkable in the range of the AA repeating unit (β-alanine unit) from 10 to 40 mol-% (e. g. AA/CLN =  27 : 73, degradation 44%), while, the degradability for the non-enzymatic hydrolysis rose with increasing AA repeating unit content. The biodegradation of the copoly(ester amide) was evaluated using a standard activated sludge (e. g. AA/CLN =  27 : 73 biodegradation 45%). The relationship between the biodegradation and the polymer composition was similar for the standard activated sludge and the enzymatic hydrolysis.

Poly(ethylene terephthalate)/copoly(succinic anhydride/ethylene oxide) copolymers, (PET/PES copolymers) were synthesized by the transreaction between PET and PES and characterized with GPC, ¹H NMR, and DSC. Most of the copolymers obtained were random copolymers. The films cast of these copolymers were transparent. The thermal, mechanical properties, and biodegradability of the copolymers obtained were studied with respect to the composition and lengths of aliphatic and aromatic units in the copolymers. In the copolymers having high PET content, the melting points, due to the PET segment, were observed by DSC measurement, although the fusion heats of the copolymers were small. The enzymatic hydrolyzability by a lipase from Rhizopus arrhizus and biodegradability by activated sludge of the copolymers decreased with an increase in PET content. When the length of succinic acid unit in the copolymer was below 2, the hydrolyzability of the copolymers decreased considerably. The tensile strengths of the cast films prepared from the copolymers synthesized by the transreaction increased with an increase in PET content, whereas, the elongations at break decreased. Their tensile strengths were half, and the elongations were double compared to those of PET homopolymer film. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4478–4489, 2000

The polymerization of L-lactide (LA) was carried out in the presence of tin(II) 2-ethylhexanoate, Sn-(Oct)2and copoly[succinic anhydride (SA)-ethylene oxide (EO)] which has a hydroxyl end group. The synthesized copolymers were characterized by GPC, 1H NMR, 13C NMR, and DSC. The products were block copolymers consisting of copoly(SA-EO) and poly(L-lactide) (PLA) segments. Optical micrographs of the copolymer films confirmed the presence of spherulitic morphology. Spherulite size was enhanced with increase in the LA content in the copolymers. The block copolymers were hydrolyzed with or without lipase and biodegraded by enzymes from microorganisms in activated sludge. Hydrolyzability decreased with increase in LA content in the block copolymers. The solubility of the block copolymers containing LA segment in tetrahydrofuran (THF) was higher than that of copoly(SA-EO).

The ring-opening copolymerization of succinic anhydride (SA) with ethylene oxide (EO) was carried out by using mainly magnesium diethoxide (ME) as an initiator. ME was superior with respect to polymerization yield and number-average molecular weight (Mn) of the copolymers obtained. The copolymers were found to be alternating copolymers independent of feed monomer molar ratio. The yield and the Mnof the copolymers increased with the polymerization temperature and the time within 48 h. There was a maximum of Mnat a time of 48 h, at 100°C. The Mnof the alternating copolymers was as high as 1.3 × 104. The Mnof the copolymers increased proportionally with the increase of monomer/initiator molar ratio (M/I) up to M/I = 400. From analysis of the end-groups of low Mnof copolymers by 1H n.m.r., these copolymers were a mixture of two copolymers having different end groups. One had ethyl ester group connecting with SA at either end group, the other had ethyl ester group connecting with SA and hydroxyl group connecting with EO. © 1997 Elsevier Science Ltd.

Two series of novel oligo(ester amide)s based on sebacic acid/1,6-hexanediamine/ɛ-caprolactone and octadecanedioic acid/1,6-hexanediamine/ɛ-caprolactone were synthesized. The determination of the molecular weights with both gel permeation chromatography and 1H nuclear magnetic resonance (n.m.r.) showed that they vary from 1000 to 6000. Differential scanning calorimetry and thermogravimetric analysis were employed for determining glass transitions, melting points, heats of melting and decomposition temperatures of the oligo(ester amide)s. Fourier-transform infra-red and 1H-13C n.m.r. spectra were taken to confirm the composition of the novel oligo(ester amide)s. The test of enzymatic hydrolysis was employed to assess the potential biodegradability of these oligomers.

The enzymatic degradation of the chain-extended copoly[succinic anhydride (SA)/ethylene oxide (EO)], synthesized by the ring-opening copolymerization, was studied using the lipase from Rhizopus arrhizus. A decrease in SA content of these copolymers resulted in substantial increase of their degradability. The lipase concentration was shown to enhance considerably the degradation of the copolymer film (polymer composition SA/EO=42/58 mol%) which exhibited the highest susceptibility to degradation. The water contact angle measurements conducted on the films and their water absorption were related to the easy of adsorption of the lipase to the surface of the copolymer film and were not found to be particularly influenced by SA content. The degrees of crystallinity of the copolymer films, determined from wide angle X-ray diffraction, were within a range 24 to 28% as SA content increased from 42 to 48 mol%. The small angle X-ray scattering profiles indicated that these copolymer films had alternating crystalline layer structure. The long-period between lamellar crystalline, calculated from scattering angle, was found to increase from 80 to 110 Å with a decrease in SA content. The long-period, related to the size of amorphous region, was shown to affect the enzymatic degradation of copolymer by the lipase.

Chain-extension reactions were carried out using titanium-iso-propoxide (TIP) as a catalyst for a series of polyesters or copolyesterethers with low molecular weights (Mn=1500–10,000) synthesized by the ring-opening copolymerization of succinic anhydride (SA) with ethylene oxide (EO). The copolymers having aMn from 25,000 to 50,000 of different properties were obtained. Both the melting point (Tm) and the fusion heat (δH), which indicate the crystallinity of the copolymers, rose with an increase in SA content in the copolymers. Semitransparent films were prepared by compression molding of the copolymers. The biodegradation of the copolymer films was evaluated by enzymatic hydrolysis by lipases and by an aerobic gas evolution test in standard activated sludge. The hydrolyzability of these copolymers by three kinds of lipases was affected by their copolymer composition SA/EO, form, andMn. The copolyesterether (SA/EO=43/57,Mn=48,900) was more easily biodegraded by standard activated sludge compared to the polyester (SA/EO=47/53,Mn=36,300).

Abstract: Biodegradable polyesters were synthesized by ring-opening copolymerization of gamma-butyrolactone (BL) and its derivatives withl-lactide (LLA). Although tetraphenyl tin was the main catalyst used, other organometallic catalysts were used as well.1H and13C NMR spectra showed that poly(BL-co-LLA)s were statistical and that their number-average molecular weights were as high as 7×104. The maximum BL content obtained from copolymerization BL/LLA was around 17%. TheT m andT g values of the copolymers showed a gradual depression with an increase in BL content. NoT m was obtained for the copolymers containing more than 13 mol% BL. The biodegradability of the copolyesters was evaluated by enzymatic hydrolysis and nonenzymatic hydrolysis tests. The enzymatic hydrolysis was carried out at 37°C for 24 h using lipases fromRhizopus arrhizus andR. delemar. Hydrolyses by both lipases showed that an increase in BL content of the copolymer resulted in enhanced biodegradability. Nonenzymatic accelerated hydrolysis of copolymers at 70°C was found to increase proportionally to their exposure time. The hydrolysis rate of these copolymers was considerably faster than that of PLLA. The higher hydrolyzability was recorded for the BL-rich copolymers. The copolymerization of gamma-methyl-gamma-butyrolactone (MBL) or gamma-ethyl-gamma-butyrolactone (EBL) with LLA resulted in relatively LA-rich copolymers.

Two methods, known as the low and the high temperature methods, which consist of casting aqueous solutions of hydroxypropyl starch and gelatin at 20 and 60°C, respectively, were employed for film preparation. The physical (thermal, mechanical and gas/water permeation) properties of these composite films, plasticized with water or polyols, were studied. An increase in the total plasticizer content resulted in a considerable decrease in elasticity modulus and tensile strength (up to 60% of the original values when 25% plasticizer was added), whereas the percentage elongation increased (up to 200% compared to the original values). The low temperature method led to the development of higher percentage renaturation (crystallinity) of gelatin which resulted in a decrease, by one or two magnitude orders, of CO2 and O2 permeability in the hydroxypropyl starch/gelatin blends. An increase in the total plasticizer content (water, polyols) of these blends was found to be proportional to an increase in their gas permeability.

A new class of cyclam, octamethylcyclam, and its related compounds bearing tetramethylethane, cis-cyclohexane, or trans-cyclohexane subunit(s) have been synthesized. Nickel(II) complexes with sterically congested ligands have been shown to be low-spin complexes in water, while those with less congested ligands to be mixtures of low-spin and high-spin ones. Nickel(II) complexes with sterically congested ligands have been also exhibited to have higher half-wave potentials (E1/2(NiII,III)) than those of the complexes with less congested ligands.

Novel copolyesteramides were synthesized by reacting L-lactic acid (LLA) with ε-caprolactam (CLM) in the presence of Fe, Sn or Zn powder as a catalyst. The molecular weight of the copolymers was 3.7 × 10³ when using tin as a catalyst. For the purpose of increasing the molecular weight of the copolymer, azeotropic removal of water from the reaction mixture was performed; the molecular weight increased to 8.4 × 10³. The biodegradability of the copolymers was evaluated by using a standard activated sludge. One of the copolyesteramides (mole ratio LLA/CLM = 45/55, Mn = 8.4 × 10³) was degraded up to 50% after 33 d in contact with an activated sludge.

Novel copolyesteramides were synthesized by reacting L-lactic acid (LLA) with ε-caprolactam (CLM) in the presence of Fe, Sn or Zn powder as a catalyst. The molecular weight of the copolymers was 3.7 × 10³ when using tin as a catalyst. For the purpose of increasing the molecular weight of the copolymer, azeotropic removal of water from the reaction mixture was performed; the molecular weight increased to 8.4 × 10³. The biodegradability of the copolymers was evaluated by using a standard activated sludge. One of the copolyesteramides (mole ratio LLA/CLM = 45/55, Mn = 8.4 × 10³) was degraded up to 50% after 33 d in contact with an activated sludge.

Toward the electromagnetic wave shielding materials for the electronic equipment, organo-soluble, palladium chelating, and biodegradable chitosan derivatives were successfully prepared.

N-Acetyl-D-glucosamine, which is a focusing material for the improvement of osteoarthritis, was obtained from β-chitin by enzymatic hydrolysis in high yield (76%).

Tricarbonyl (?6-[6]paracyclophane)chromium has been synthesized and its spectral properties have been investigated.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.