No abstract

A new bicomponent conetwork, poly(ethyl acrylate)-linked-polyisobutylene (PEtA-l-PIB), was synthesized by radical copolymerization of equal amounts of telechelic α,ω-dimethacrylic PIB (MA−PIB−MA, M n/(kg/mol) = 11.2, M w/M n = 1.12, and MA/chain = 2.0) obtained via quasi-living carbocationic polymerization and ethyl acrylate in 10% solution for each component in a common solvent, tetrahydrofuran, followed by extraction and drying. Low amounts of extractables (2.5% in acetone and 4.6% in hexane) and nearly theoretical composition (51% PEtA and 49% PIB) of the resulting conetwork indicate efficient network formation; i.e., this new conetwork is composed of PIB chains connected at each end to two PEtA chains. DSC experiments gave close to literature value T g's (−68 °C for PIB and −22 °C for PEtA), indicating a segregated morphology in this conetwork. In contrast to reported results for similar conetworks containing PIB and other polymers with polar groups, surface analysis with XPS found no significant difference in surface and bulk compositions in PEtA-l-PIB. For the first time in the field of bicomponent segmented conetworks, the structure of a conetwork was investigated by small-angle neutron scattering (SANS) in both the relaxed and strained states. Two correlation peaks were observed at q*/Å-1 = 0.035 and at 3q*. The measured value of q* is less by more than a factor of 2 than that predicted by de Gennes for random bicomponent (“grafted”) networks. The macroscopically homogeneous conetwork is characterized by nanoscale local layered like segregation with a correlation length of 445 Å and periodicity of 180 Å. This structure does not deform affinely with the macroscopic deformation. The measured modulus is in excellent agreement with an affine network prediction assuming that each MA−PIB−MA chain gives rise to three elastic strands in the network.

SUMMARY: Covalent end-on grafting of poly(ethy1ene glycol) (PEG) onto a polysulfone (PSf) surface using a-4-azidobenzoyl-o-methoxy-PEG (ABMPEG) is described. Photoreactive ABMPEG was synthesized by reacting monomethoxy-PEG (MPEG) with 4-azidobenzoyl chloride, yielding complete substitution of the hydroxyl groups. After adsorption from aqueous solutions, ABMPEG was photo-grafted under wet conditions onto PSf ultrafiltration (UF) membranes. Contact angle (CA) measurements showed the increased hydrophilicity of modified membranes and the irreversibility of the modification. Bovine serum albumin (BSA) adsorption decreased by 70% and the permeability decay after protein adsorption became less severe for the modified membranes compared to unmodified reference membranes.

No abstract

Living atom transfer radical polymerization (ATRP) of 4-acetoxystyrene (l), a protected 4-vinylphenol, leading to poly(4-acetoxystyrene) with well-defined molecular weight and narrow molecular weight distribution was carried out in bulk with a,a'-dibromoxylene(2)/CuBr/2,2-bipyridine(bpy) as initiating system. A linear M,, versus monomer conversion plot was found in good accordance with the theoretical line, indicating 100% initiating efficiency. The polymerization is first order in respect to monomer up to about 70% monomer conversion. Deviations from linearity at higher conversion in the first order plot are due to physical effects, i. e., to the increase of the viscosity of the reaction medium. The resulting 1-bromo-I-phenylethyl-telechelic poly(4-acetoxystyrene) (3) is a precursor of the hydrophilic poly(4-vinylphenol) and a potential new macroinitiator.