Intermolecular chain transfer to polymer with chain scission: general treatment and determination of kp/ktr in L,L-lactide polymerization

A general kinetic treatment of the system with intermolecular chain transfer followed by fast reinitiation is given. It leads to the broadening of the molecular weight distribution (MWD), the number of growing chains being invariable. Thus, this system can be considered as a special case of living polymerization. A general method has been elaborated allowing the determination of the ratio of the rate constant of propagation (k_p) to the rate constant of the bimolecular transfer (k⁽²⁾_tr) from the dependence of the MWD on monomer conversion. Numerical values of k_p/k⁽²⁾_tr equal to ≈ 10² and 25 were thus determined for the polymerization of L , L -lactide (L , L -dilactide) initiated with aluminium tris(isopropoxide) trimer ({Al(OⁱPr)₃}₃) and tributyltin ethoxide (ⁿBu₃SnOEt), respectively.     

Second neighbours velocities and size of faces in crystal habit

Influence of growth velocities of first and second neighbours on the presence and size of the face in the crystal habit has been studied. It was established and confirmed that the consecutive neighbour affects the face size only after the disappearance of the previous neighbour. The formula for critical growth velocity governing disappearance of faces has been discussed.     

Synthesis of functional polymers with acetal-monosaccharide moieties

The polycondensation of methyl α-D-mannopyranoside ( 1 ) with 1,n-bis(formylphenoxy)alkanes ( 2 ), using acidic catalysts, leads to the formation of linear polymers and macrocyclic compounds. The structure of the polymer and macrocycles was determined by ¹H, ¹³C NMR spectroscopy and ESI-MS analysis.