Calorimetric study of tetramethylene urethane and of poly(tetramethylene urethane) between 0 and 300 K

Abstract

SUMMARY:In an adiabatic vacuum calorimeter the temperature dependence of the heat capacity C p 0 of tetramethylene urethane (TMU) (2-oxo-hexahydro-1,3-oxazepine) and poly(tetramethylene urethane) (PTMU) was studied between 4.3 and 300 K with an uncertainty of about 0.2%. In a calorimeter with a static bomb and an isothermal shield the energies of combustion D U comb of the monomer and the polymer were measured. From the experimental data the thermodynamic functions

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

“…More detailed tables of the standard thermodynamic functions of these substances are given in ref. [12][13][14][15][16] The thermodynamic functions of the polyurethanes in the completely amorphous and crystalline states were calculated earlier. [22] The zero entropy of the crystalline polymers was assumed to be equal to zero.…”

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

“…Five, six, and seven membered cyclic urethanes were prepared, however, for thermodynamical reasons only the unsubstituted six and seven membered cyclic carbamates 69 and 70 are polymerized by ring-opening polymerization. [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.…”

“…[36] The polymerization of tetramethylene urethane (TeU) follows the same mechanism, however, due to the higher negative value of the free polymerization enthalpy (DG = -41 kJ/mol) compared to the free polymerization enthalpy of trimethylene urethane (DG = -14 kJ/mol) the polymerization is performed at lower temperature, i. e. T = 67 8C which is five degrees above the melting point of the monomer. [37,41] Block copolymers comprising a poly(tetrahydrofuran) (PTHF) and a PTU or PTeU block were prepared by controlled cationic sequential polymerization of first THF and then TU or TeU. [42,43] The synthetic route to A -B and A -B -A block copolymers where B is a PTHF and A a PTU or a PTeU block, will be described for TeU as the monomer.…”

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]. The standard Gibbs function ∆G 0 pol for the unsubstituted cyclic five, six and seven membered urethane monomers were determined from calorimetric measurements to be -1 kJ/mol, -18 kJ/mol and -42 kJ/mol, respectively.…”