Abstract
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.
Highlights
Typical linear polyurethane (PUR) is built with (i) a soft segment, which gives flexibility and softness of polymer and (ii) a hard segment the aim of which is to increase stiffness, hardness changes, etc
What was interesting was the presence of R,S-PHB in the PURs structure reduced melting enthalpy of hard segments
Aliphatic PURs with synthetic poly([R,S]-3-hydroxybutyrate) (R,S-PHB) in soft segments were synthesized with the prepolymer method
Summary
Typical linear polyurethane (PUR) is built with (i) a soft segment (based on oligomeric polyester- or polyetherdiol), which gives flexibility and softness of polymer and (ii) a hard segment (synthetized with diisocyanate and low molecular chain extender) the aim of which is to increase stiffness, hardness changes, etc. Whereas hydrogen bonds of the urethane group with oxygen of the soft segment can reduce chains mobility and their ordering [1]. The presence of side chains in their structure significantly influences the properties and linear polymers. The PUR structure reduces a possibility of chains to order and form soft and hard domains. Both short and long side-chains can influence urethane groups to create hydrogen bonds is strongly affected by side-chains Both short and long aside-chains possibilitycan of interaction polymer chains. R,S-PHB influences thermal, and sorptive surface [7]profile properties of linear and cross-linking. The influence of PCLtriol and R,S-PHB presence in the soft segments structure on thermal and sorptive properties of obtained PURs was estimated
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