Crystal orientation and melting behavior of poly(

ε

-caprolactone) in a diblock copolymer of poly(

ε

-caprolactone)-

block

-poly(2

5-bis[4-methoxyphenyl]oxycarbonyl)styrene) (PCL-

b

-PMPCS) was investigated. The degrees of polymerization of the PCL and PMPCS block are 200 and 98

respectively. With the PMPCS in a columnar liquid crystalline phase

the diblock is rod-coil one

which exhibits a lamellar phase morphology with the PCL layer thickness of 15.2 nm. Since the glass transition temperature of PMPCS block is much higher than the melting temperature of PCL

the crystallization of PCL is in a one-dimensionally "hard" confinement environment. Mainly on the basis of two-dimensional wide-angle X-ray diffraction experiments

we identified the orientation of PCL isothermally crystallized at various crystallization temperatures (

Tc

s

). At high

T

c

s (

T

c

≥ 10℃)

the

c

-axis of the PCL crystal is along the layer normal of the microphase-separated sturcture. Decreasing

T

c

can result in the tilting of PCL

c

-axis with respect to the layer normal. The lower the

T

c

is

the more the

c

-axis inclines. Meanwhile

the

b

-axis of PCL remains perpendicular to the layer normal. At a very low

T

c

of −78℃

the orientation of the PCL crystals is completely random. For the samples isothermally crystallized at

T

c

≤ 10℃

double melting behavior can be observed. While the low temperature endotherm reflects the melting of the crystals originally formed at the

T

c

applied

the high temperature one is associated with the crystals subjected to the process of recrystallization/reorganization upon heating due to the annealing effect.