Degradability of cross-linked polyurethanes/chitosan composites

Abstract

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.Keywords: cross-linked polyurethanes, chitosan, composites, polyurethane degradability. Podatność na degradację kompozytów usieciowanych poliuretanów z chitozanemStreszczenie: Poliuretany zawierające syntetyczny poli([R,S]-3-hydroksymaślan) w segmencie gięt-kim oraz polikaprolaktonotriol jako związek sieciujący zmieszano z chitozanem i poddano degradacji w roztworach hydrolitycznym i utleniającym. Postęp rozkładu kompozytów oceniano na podstawie zmiany masy, powierzchni i właściwości termicznych próbek. Zarówno zwiększenie zawartości poli([R,S]-3-hydroksymaślanu) w segmencie giętkim poliuretanów, jak i zmieszanie ich z chitozanem spowodowało wzrost podatności usieciowanych poliuretanów na degradację w obu rodzajach roztworów.Słowa kluczowe: usieciowane poliuretany, chitozan, kompozyty, podatność poliuretanów na degradację.Cross-linked polyurethanes (PUR) are mainly obtained in the reaction of isocyanates with polyols and low-molecular compounds, of which at least one type of reagent is multifunctional [1][2][3]. They can be also synthesized via reaction with using unsaturated compounds [4,5]. Cross-linked polyurethanes are not dissolved in the solvent but swelled. With an increase in the degree of cross-linking their elasticity decreases but stiffness increases. They are mainly used as coatings, membrane and shape memory materials [6].Cross-linked polyurethanes are generally less susceptible to degradation than linear polyurethanes. The presence of cross-linkages between chains of polyurethane significantly hinders the migration of water with enzymes, free radicals, and other degradative molecules into the polymer network [6].But, in some cases, the presence of a triol cross-linker in polyurethane structure leads to a polymer with no phase separation. Disordering of the polymer network and reduced mobility of the chains (as a result of chemical cross-linking) allow the ester/ether groups to be exposed to water. In this case cross-linked polyurethanes can be susceptible to degradation [7].The process of degradation of cross-linked polyurethanes can be accelerated by introducing the groups susceptible to degradation (such as ester groups) into their structure or by blending with degradable polymers. Natural polymers or their synthetic analogues (such as polyhydroxybutyrate, polycaprolactone, and chitosan) can be used as part of polyurethane network or as composite fillers.

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

“…2 Weight changes of PURs and their blends with PDLLA after incubation in the buffer solution. Data for PUR10 and PUR30 presented in (Brzeska et al 2017 )

Fig. 3 Weight changes of PURs and their blends with PDLLA after incubation in oxidative solutions.

…”

“…3 Weight changes of PURs and their blends with PDLLA after incubation in oxidative solutions. Data for PUR10 and PUR30 presented in (Brzeska et al 2017 ) …”

“…The synthesis of polyurethanes was carried out in a two-step reaction (as showed in Scheme 1 ), with the molar ratio of NCO:OH = 4:1 in the prepolymer step (Brzeska et al 2017 ). Prepolymer of polyurethanes was synthesized for 3 h at 70–75 °C under vacuum with mixed oligomeroles (in the weight ratio of R,S-PHB:PCL triol = 10:90 or 30:70) and H 12 MDI.…”

Preparation, Physicochemical Properties and Hemocompatibility of Biodegradable Chitooligosaccharide-Based Polyurethane

“…On the one hand, chemical crosslinked network can somewhat destroy the ordering of polymer structure and reduce the mobility of the chain, which allow the ester groups to be easily exposed to water and result in an increased susceptibility to degradation [38]. On the other hand, the process of degradation of crosslinked materials can be accelerated by blending with polymers susceptible to degradation [50]. In the case of CPU with higher COS content (especially CPU-2.0), the unreacted COS being physically mixed with CPU, as described in XRD, acts as a plasticizer and makes the material more ductile.…”

The Effect of Chitosan on the Chemical Structure, Morphology, and Selected Properties of Polyurethane/Chitosan Composites

“…In the literature there are known studies about preparing the waterborne polyurethanes based on chitosan [16][17][18][19][20], polyurethanes coated and impregnated via chitosan [21][22][23], polyurethanes with grafted chitosan as a side chain [24][25][26][27][28], and the polyurethane/chitosan composites (PUR/Chit) [29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48]. PUR modification with Chit may have a beneficial effect on the use of these materials and their environmental friendliness.…”