[n]-Polyurethane: Synthese und Charakterisierung

Abstract

Über 50 Jahre nach Otto Bayers detaillierter Beschreibung der [m,n]‐Polyurethane wird nun eine allgemeine Synthese der [n]‐Polyurethane 1 beschrieben. Diese Reihe aliphatischer [n]‐Polyurethane wird durch In‐situ‐Polymerisation der entsprechenden α,ω‐Isocyanatalkoholmonomere erhalten, die ihrerseits aus linearen α,ω‐Aminoalkoholen und Di‐tert‐butyltricarbonat hergestellt werden. Man erhält so Polymere mit hohem Molekulargewicht und einheitlicher Mikrostruktur, deren Schmelzpunkte einen starke Alternanz (Gerade‐Ungerade‐Effekt) zeigen.

Thermodynamics of Aliphatic Cyclic Urethanes, of Their Ring-Opening Polymerization, and of Corresponding Polyurethanes

“…[22,24] It should be noted that polyurethanes with 7 a m a 13 were already synthesized by Meijer et al using the polymerization of isocyanatoalcohols. [25] The thermodynamic properties of the monomers and the polymers with 7 a m a 13 are summarized in Table 6.…”

Expected and unexpected reactions in ring-opening (co)polymerization

“…Sequential copolymerization of DTC and ECL [25] with a variety of initiating systems results in block copolymers, if the conditions are carefully chosen so that transesterification is suppressed, e. g. with Mg and Al based initiators. [5][6][7] For these copolymers only DTC-DTC (31) and ECL-ECL homodiads (34) are detected in the 13 C NMR spectrum.…”

“…Meijer et al prepared [5][6][7][8][9][10][11][12][13]-polyurethanes 66 with m = 4 -12 CH 2 groups starting from the corresponding aminoalcohols 67 and ditert-butyl-tricarbonat in solution. [34] The intermediate in this reaction is an a-hydroxy-x-isocyanato derivative 68 which reacts in situ to form the polyurethane. We prepared [4]-and [5]-polyurethanes via cationic ring-opening polymerization [35][36][37] of the corresponding 6-and 7-membered cyclic carbamates 69 and 70 and [3]-[7]-polyurethanes via polycondensation of a-hydroxy-x-O-phenylurethanes 71.…”

“…[39][40][41] The melting points of these [n]-polyurethanes show the odd even effect which was observed also for the respective polyamides. [34,38] The polymerization of trimethylene urethane (TU, 69) was carried out to yield poly(trimethylene urethane) [PTU, 66 (m = 3)] with a uniform microstructure in a cationically initiated process with TfOMe as the initiator [35,36,40] (Eq. (5)).…”

Block copolymers comprising a polytetrahydrofuran block and one or two [5]-polyurethane block(s): synthesis and characterization

“…[4]-and [5]polyurethanes were prepared by means of cationic ring opening polymerization, other [n]-polyurethanes were prepared by means of polycondensation of suitable α,ω−substituted monomers [7,8]. The thermodynamic characteristics of the monomer/polymer equilibrium were determined for several systems [9][10][11][12][13].…”