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NALLET, Frederic

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TitleKinetics of the water swelling of amphiphilic diblockcopolymers with adhesive propertiesAuthor(s)NALLET, FredericCitation物性研究 (2006), 87(1): 40-41Issue Date2006-10-20URL http://hdl.handle.net/2433/110664RightType Departmental Bulletin PaperTextversionpublisherKyoto University研究会報告Kinetics of the water swelling of amphiphilic diblock copolymers with adhesive properties Centre de recherche Paul-Pascal， CNRS and Bordeaux-l Univ. Frederic NALLET 1 1 Introd uction Asymmetric diblock AB copolymers， inthe case where the longer block A is both hydrophobic and“so此"， whereas the shorter block B is hydrophilic and "hard" are the subject of this study. Materials with such a particular combination of physicかchemicaland mech但lIcalproperties have distinctive advantages， inparticular for designing water-compatible adhesive materials. Here， we report about the kinetics of the swelling with water of such materials， asmonitored through gravimetry and-in some sense-“tim←resolved" small-angle x-ray scattering (SAXS). Disordered， as well as 3D-， 2D-or 1D-ordered structures are al found to absorb significant amounts of water. 2 Gravimetry A climatic test chamber is used for the kinetic study at short and intermediate times. Samples， deposited錨 filmsof thickness 100μm onto metallic substrates， are weighed at regular time intervals for about one day. This experiment gives direct access to the kinetics at intermediate tim回， i. e. in the range 102-104 s， with a satisfactory description in terms of a Fickian behaviour and indirect evidences for pl部 ticisationat short times. It also reveals the occurrence of non-Fickian processes in the long-time limit， better investigated with SAXS-see below. As far錨 gravimetryis concerned， the structured amphiphilic copolymers， although featuring a mostly hydrophobic matrix， are found to essentially behave as homogeneous， effective media. The materials exhibit a high hydrophilic character linearly incre槌 ingwith the amphiphilic content， where槌 waterdiffusivity simultaneously decre舗 es.3 Small-angle x-ray scattering The structural characteristics of the slow relaxation phenomena evidenced by gravimetry have been studied by SAXS. Though a conventional x-ray source has been used (with spectra recorded in typically 4 x 103 s)， the study is nearly “timかresolved"， thanks to the 1訂 gevalue of the assかciated ch町 acteristictimes， inthe range of 105 s.Depending on the composition of the (initially 1 E-mail: nallet<dcrpp-bordeaux.cnrs.fr -40一「ソフトマターの物理学 2006Jdry) block copolymers， the uptake of water leads to either simple swelling-the initial micrかstructure is preserved during the swelling process-or to structural transitions. In the latter case， the transition is most often directly revealed by a qualitative analysis of the spectra. Evidence for a “hidden"， swelling-induced body-centred-tかface-centredcubic structural transition will be discussed in terms of a detailed analysis of the SAXS spectra， asgiven by the example displayed in Fig. 1. 0.32 0.3 0.28 0.26 0.24 +sz 022 0.2 I •0.18 0.16 0.14 。• • ロロロ日口口 O0.0 .....00 0 5α)()() 1∞α)() 1500002αゅ∞25α)()Q300c削35α)()()t [s] Figure 1: Time dependence of the amphiphilic domain volume fraction Ow，槌 suminga bcc structure at shorter times (0 or・)， and a fcc one at longer times (口 or圃).The structural transition takes place in the range where open symbols are used Simple swelling，ωwell as swelling-induced structural transitions imply that the large amounts of water accommodated within the amphiphilic materials require local and slow copoly-mer chain rearrangements. Acknowledgment The content of this presentation results from the PhD work of Sylwia POIVET，部wellas from the strenuous efforts in macromolecular synthesis of post-doctoral fellows， Kai SHIERHOLZ組 dGinuABRAHAM [1]. The major involvement and support-including supervision-of P部 caleFABRE町egratefully acknowledged. A more complete account of this work can be found in Ref. [2]. References [1] K. Scl出rholzet α1.， Macromolecules 36 (2003) 5995 [2] S. Poivet et α1.， Eur. Phys. J. E， toappe町 (2006)-41-

Kinetics of the water swelling of amphiphilic diblock copolymers with adhesive properties

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Kinetics of the water swelling of amphiphilic diblock copolymers with adhesive properties

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