Abstract
The synthesis of poly(urethane-urea) (PUUs) bearing deactivated diamines within the backbone polymer chain is presented. Several deactivated diamines present interesting properties for several applications in the biomaterial field due to their attractive biocompatibility. Through an activation with Chloro-(trimethyl)silane (Cl-TMS) during the polymerization reaction, the reactivity of these diamines against diisocyanates was triggered, leading to PUUs with high performance. Indeed, through this activation protocol, the obtained molecular weights and mechanical features increased considerably respect to PUUs prepared following the standard conditions. In addition, to demonstrate the feasibility and versatility of this synthetic approach, diisocyanate with different reactivity were also addressed. The experimental work is supported by calculations of the electronic parameters of diisocyanate and diamines, using quantum mechanical methods.
Highlights
The poly(urethane urea) (PUUs) polymers are a subclass of the generic polyurethane (PU) family that has been widely studied
The study was focused on the synthesis of model polyureas, since they act as a hard phase within the matrix of segmented poly(urethane-urea)s
Ensuring that the diamine activation protocol leads to soluble polymers during polymer synthesis is a key element in obtaining high molecular weight polymers because precipitation, stoichiometric imbalance, composition drift issues are completely avoided
Summary
The poly(urethane urea) (PUUs) polymers are a subclass of the generic polyurethane (PU) family that has been widely studied. The polymerization can be carried out by mixing all the reactants at once, one shot method or in two stages, where initially the diisocyanate reacts with the macrodiol yielding an end-capped isocyanate prepolymer which reacts, in a second step, with the chain extender (diamine in PUUs) giving the corresponding polymeric chain, prepolymer method [1,2,3] This method is preferred in PUUs to the direct polycondensation of a mixture of diamines and diols with the diisocyanate compound because due to the high reactivity of amines compared to alcohols [4,5,6,7], in the early stages of the reaction, polymer chains rich in urea moieties will be preferentially formed. Thhaemrpeearcetdionanodf tihseocmyaanteartiealasnodbthayinderdoxwylouglrdourpeascihs luimsuitaeldlymcaetcahlyanzeicdalbpyerformance [9]. tertiary aminesTahnedreoarcgtaionnoomfeitsaolclyicancoamtepaonudnhdysdwrohxeyrlegarsotuhpesriesaucstuioanllyofcaistoalcyyzaendatbeys taenrtdiary amines and amines usuallyodrgoannootmneeteadlliccactaolmyspto[u4,n1d0s].whereas the reaction of isocyanates and amines usually do not
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