Surfactant Mediated Microphase Separation in Miscible Block Copolymer of Poly(4-vinyl pyridine-b-hydroxybutylacrylate)

Miscible disordered block copolymers(BCPs)are rarely studied due to the limits in self-assembly into ordered microstructures.Herein,we proposed a facile method for the transformation of disordered miscible BCPs to comb-like BCPs with well-ordered microphase separation structures via blending with amphiphilic surfactants.In this work,poly(4-vinyl pyridine-b-hydroxybutylacrylate)(P4VP-b-P4HBA)was applied as a model of miscible disordered BCPs and the microphase separation was induced via blending with surfactants of dodecylbenzene sulfonic acid(DBSA)and 3-pentadecylphenol(PDP).The ordered microstructures including spherical and cylindrical morphologies were confirmed by transmission electron microscopy(TEM)and small angle X-ray scattering(SAXS)investigation.These ordered microstructures thermal sensitive,in which ordered and disordered transformation(ODT)was observed in the blend of P4VP-b-P4HBA and PDP whereas it disappeared in the blend of P4VP-b-P4HBA and DBSA.The results show that the thermal stability of the ordered microstructures are strongly depends on the interactions between the miscible BCPs and surfactants,which investigated by in situ SAXS and Fourier transform infrared spectrometer(FTIR).The combination of miscible BCPs and surfactant creates a feasible strategy to fabricate ordered nanostructures,which could be employed to develop complicated nanomaterials.

Micro-Macro Scale Relationship in Creep Deformation of Ultra High Molecular Weight Polyethylene

Macroscopic and microscale creep deformations of UHMWPE were investigated by using in situ SAXS.A methodology for the measurement of the local creep deformation of inter-lamellar amorphous phase has been proposed.The local strain of inter-lamellar amorphous phase(£a)and macroscopic strain(£macro)were evaluated and they were compared to study the relati on ship betwee n macroscopic and microscale creep deformation of UHMWPE.Both of them exhibit two deformation regions against creep time.The entanglements show a strong impact on both the macroscopic and local inter-lamellar amorphous phase creep behavior and they can be well correlated to the molecular weight between two entanglements estimated from strain-hardening modulus.Compared to the macroscopic creep deformation,local inter-lamellar amorphous layers have a smaller creep deformation.From the local creep measurement,the apparent modulus of inter-lamellar amorphous phase can also be estimated(200<Ma<500 MPa).These values are much higher than the Young's modulus of bulk amorphous PE,which can be well explained by the confinement of the lamellar stacks and the enhancement of the amorphous phase with the relatively high concentration of entanglements.This study provides a useful means and quantitative data for achieving the scale transition between the micro and the macro structural levels for the study of viscos-elastic deformation.