very recently that Esker and co-workers extensively studied PCL crystallization mechanism in

the collapse region by Brewster angle microscopy and isobaric area relaxation analyseS.101,119

The only example in the previous literature investigating the A/W self-assembly of PCL-based

block copolymers was reported by Lee et al. for an architecture with two linear PCL chains

anchored to a dendritic hydrophilic head.120

 Chemically attaching a hydrophilic PEO block to a hydrophobic PCL block enhances the

amphiphilicity and the surface activity of the resulting block copolymer, allowing higher surface

pressures to be reached, as previously shown for other PEO-based amphiphilic block

copolymers.22,23 To our knowledge, no work has been reported on the A/W interfacial behavior

of block copolymers based on PEO and PCL. With a view toward guest encapsulation, we

recently reported the synthesi s of a seri es of poly(ethylene oxi de)-block-poly(s-caprol actone)

copolymers with star-shaped and linear architectures by ring-opening polymerization of e-

caprolactone at the end of hydroxyl-terminated star-shaped or linear PEO macroinitiators.121 In

the present chapter, we study the behavior of these samples as well as the corresponding PEO

and PCL homopolymers at the A/W interface (Langmuir monolayers) by surface pressure

measurements isothermss, compression-expansion hysteresis, and isobaric relaxation

experiments), and we employ AFM to characterize the Langmuir-Blodgett (LB) films'

morphologies after transfer onto hydrophilic mica substrates. The PEO-b-PCL five-arm stars

consist of a hydrophilic PEO core with 9 ethylene oxide units/arm with hydrophobic PCL chains

at the star periphery. Each star contains different amounts of PCL, varying from 0 to 18 e-

caprolactone units/arm (Figure 4-1 and Table 4-1). The linear PEO-b-PCL diblock copolymers

synthesized from a linear PEO macroinitiator (PEO2670, Mn = 2,670 g/mol, ~ 60 ethylene oxide

repeat units) contain different amounts of PCL, varying from 11 to 35 e-caprolactone repeat units