Branched polyurethanes based on synthetic polyhydroxybutyrate with tunable structure and properties

Branched, aliphatic polyurethanes (PURs) were synthesized and compared to linear analogues. The influence of polycaprolactonetriol and synthetic poly([R,S]-3-hydroxybutyrate) (R,S-PHB) in soft segments on structure, thermal and sorptive properties of PURs was determined. Using FTIR and Raman spectroscopies it was found that increasing the R,S-PHB amount in the structure of branched PURs reduced a tendency of urethane groups to hydrogen bonding. Melting enthalpies (on DSC thermograms) of both soft and hard segments of linear PURs were higher than branched PURs, suggesting that linear PURs were more crystalline. Oil sorption by samples of linear and branched PURs, containing only polycaprolactone chains in soft segments, was higher than in the case of samples with R,S-PHB in their structure. Branched PUR without R,S-PHB absorbed the highest amount of oil. Introducing R,S-PHB into the PUR structure increased water sorption. Thus, by operating the number of branching and the amount of poly([R,S]-3-hydroxybutyrate) in soft segments thermal and sorptive properties of aliphatic PURs could be controlled

Degradability of cross-linked polyurethanes/chitosan composites

Polyurethanes with synthetic poly([R,S]-3-hydroxybutyrate) in the soft segment and with polycaprolactone triol as cross-linker were blended with chitosan and degraded in hydrolytic and oxidative solutions. Progress of the degradation of the samples was evaluated by changes in their weight, surface topography and thermal properties. Increasing the poly([R,S]-3-hydroxybutyrate) content in soft segment as well as blending with chitosan resulted in an increase in degradability of cross-linked polyurethanes in both solutions.Centre of Polymer and Carbon Materials, Polish Academy of Sciences, University of Wolverhampton, University of the Basque Country (UPV/EHU), Gdynia Maritime Universit

Degradability of cross-linked polyurethanes based on synthetic polyhydroxybutyrate and modified with polylactide

In many areas of application of conventional non-degradable cross-linked polyurethanes (PUR), there is a need for their degradation under the influence of specific environmental factors. It is practiced by incorporation of sensitive to degradation compounds (usually of natural origin) into the polyurethane structure, or by mixing them with polyurethanes. Cross-linked polyurethanes (with 10 and 30%wt amount of synthetic poly([R,S]-3-hydroxybutyrate) (R,S-PHB) in soft segments) and their physical blends with poly([d,l]-lactide) (PDLLA) were investigated and then degraded under hydrolytic (phosphate buffer solution) and oxidative (CoCl2/H2O2) conditions. The rate of degradation was monitored by changes of samples mass, morphology of surface and their thermal properties. Despite the small weight losses of samples, the changes of thermal properties of polymers and topography of their surface indicated that they were susceptible to gradual degradation under oxidative and hydrolytic conditions. Blends of PDLLA and polyurethane with 30 wt% of R,S-PHB in soft segments and PUR/PDLLA blends absorbed more water and degraded faster than polyurethane with low amount of R,S-PHB

Degradability of polylactide films by commercial microbiological preparations for household composters

Environmentally friendly polymers such as polylactide are increasingly becoming available for use in packaging applications. The main advantages of polylactide packaging are evident. Polylactide is based on renewable resources and can be degraded in compost or soil. The studies on degradability of polylactide (PLA) films by commercial preparation of mixture of multi-active saprophytic soil microorganisms, bacteria, actinomycetes and fungi have been done. Unmodified PLA film, metalized co-extruded PLA film and modified by silicon oxide PLA film were incubated in the liquid nutritious medium (TSB) prepared to support the growth of microorganisms. The degradability of polylactide films was examined by macro and microscopic observations of surface, changes of mass and crystallinity of polymer samples before and after incubation. The obtained results indicate that the degradation of polylactide was accelerated by the presence of a biological vaccine. It was found that PLA degradation in the inoculated TSB broth was a result of both: enzymatic and chemical hydrolysis

UCL Code of Conduct for Research - Accessible Version

This is the accessible version of the UCL Code of Conduct for Research (2023) which sets out general expectations of those conducting research in the name of UCL in terms of the management of research and standards of behaviour and integrity before, during and after completion of research. The Code applies to all those conducting research at or in the name of UCL, regardless of the source of funding; all staff (including honorary staff), students, visitors and collaborators. In references below you can find a link to the interactive pdf version. </p

Environmental degradability of polycaprolactone under natural conditions

The aim of this work was an estimation of susceptibility of biodegradable poly(ε-caprolactone) (PCL) to environmental degradation in different natural environments. The commercial poly(ε-caprolactone) film, the trade name “CAPA 680”, was degraded in the compost, pond, open and harbour area of the Baltic Sea. Characteristic parameters of all natural environments were monitored during the incubation of polymer samples and their influence on degradation of PCL was discussed. Susceptibility of PCL to degradation in natural environments was evaluated based on changes of weight, crystallinity and polymer surface morphology. The rate of environmental degradation of PCL depended on the incubation place, environmental conditions and decreased in order: compost>harbour area of the Baltic Sea>open area of the Baltic Sea>pond

UCL Code of Conduct for Research

The UCL Code of Conduct for Research (2023) sets out general expectations of those conducting research in the name of UCL in terms of the management of research and standards of behaviour and integrity before, during and after completion of research. The Code applies to all those conducting research at or in the name of UCL, regardless of the source of funding; all staff (including honorary staff), students, visitors and collaborators.    In references below you can find a link to the accessible version of the Code.. </p

Green Chemistry in Medical Applications: Preliminary Assessment of Kuzu Starch Films with Plant-Based Antiseptics

The current state of the natural environment requires medical products, including dressings, to be manufactured in accordance with the principles of a sustainable economy. This assumption is perfectly met by dressings made of renewable materials and additionally filled with natural antiseptics. The use of such plant compounds is consistent with the principles of green chemistry. In this work, films based on Kuzu starch with rooibos extract and chili pepper oil extract were prepared and tested. Starch foil with silver nanoparticles and foil without additives were used as a comparative material. The chemical structures (ATR-FTIR) of the materials obtained, their thermal (DSC) and mechanical properties (tensile strength, hardness), density, swelling, water vapor permeability, water solubility, and effects on bacteria such as Staphylococcus aureus ATCC 25923 and Escherichia coli ATCC 25922 were examined. The Kuzu rooibos film had the lowest antimicrobial activity. At the same time, it was the most flexible foil and was characterized by having the best water vapor permeability and water absorption capacity. The starch film with chili extract was the weakest mechanically speaking, but it significantly inhibited the growth of Staphylococcus aureus ATCC 25923 bacteria at a level similar to that of the film with silver nanoparticles. The preliminary tests carried out on the properties of Kuzu starch films with plant extracts from rooibos tea and chili peppers indicate that they may be suitable for further research on dressing materials

Biodegradation of poly(ε-caprolactone) in natural water environments

The environmental degradation of poly(ε-caprolactone)[PCL] in natural fresh water (pond) and in The Baltic Sea is presented in this paper. The characteristic parameters of both environments were measured during experiment and their influence on the biodegradation of the samples was discussed. The loss of weight and changes of surface morphology of polymer samples were tested during the period of incubation. The poly(ε-caprolactone) was more biodegradable in natural sea water than in pond. PCL samples were completely assimilated over the period of six weeks incubation in The Baltic Sea water, but after forty two weeks incubation in natural fresh water the polymer weight loss was about 39%. The results have confirmed that the investigated polymers are susceptible to an enzymatic attack of microorganisms, but their activity depends on environments