The Synthesis of Hydroxybutyrate-Based Block Polyurethane from Telechelic Diols with Robust Thermal and Mechanical Properties

Table 1

Reaction conditions, thermal and molecular weight characteristics of PHB-diols.

Sample	Alcoholysis time (h)	Mn (×10^3 g/mol)	Mw (×10^3 g/mol)	Mw/Mn	(°C)	(J/g)	%	Hydroxyl content (molar ratio)
PHB	—	70			175	71.86	49.0
PHB I	1	21.7	34.7	1.59	169.5	71.74	48.9	1.99
PHB II	5	6.98	12.1	1.74	156.4	68.57	46.8	1.36
PHB III	6	6.18	9.72	1.57	156.2	55.9	38.1	1.97
PHB IV	8	4.42	7.33	1.66	158.3	34.38	23.5	1.92

Mn, Mw, and polydispersity (Mw/Mn) were determined by GPC (in g/mol).
Melt point was from the DSC second heating run.
Melting enthalpy was calculated from the endothermal peak in the DSC second heating run.
Crystallinity calculated from the melting enthalpy in DSC second heating run. Reference value of 100% crystallized PHB was  J/g and % = .