ISSN:
0021-8995
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
A new, highly elastomeric ABA triblock copolymer made from ω-caprolactone (ε-CL) and 1,5-dioxepan-2-one (DXO) has been synthesized by sequential addition of the comonomers in THF or toluene solution initiated by aluminum isopropoxide. Careful purification of the comonomers was essential to obtain high conversion of the final amount of the added monomer. The optimal conditions were found to be polymerization in toluene solution at 25°C with the addition of 1 molar equivalent (with respect to initiator) of pyridine, which gives a slight increase in the rate of polymerization. Under these conditions, poly(ε-CL-b-DXO-b-ε-CL) triblock copolymers of high molecular weight (Mn 〉 105 g/mol) with a relatively narrow molecular weight distribution were obtained. Thermal analysis shows a melting peak at 51°C and a glass transition at ca. -38°C, corresponding to the PCL block crystalline phase and the PDXO amorphous region, respectively. The mechanical properties of these materials are highly elastic and can be varied by tailoring the block lengths of the corresponding comonomers. Tensile modulus, tensile strength at break, and elongation at break were found to be 20-30 MPa, 50 MPa, and ca. 1000%, respectively. © 1995 John Wiley & Sons, Inc.
Additional Material:
7 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/app.1995.070551110
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