Vinyl addition polymers of substituted norbornene (NB) monomers possess very high glass-transition temperatures, making them useful in diverse applications; however, until very recently, the lack of an applicable living polymerization chemistry has precluded the synthesis of such polymers with controlled architecture, or copolymers with controlled sequence distribution. In the present work, block and random copolymers of NB monomers bearing hydroxyhexafluoroisopropyl and n-butyl substituents (HFANB and BuNB) are synthesized via living vinyl addition polymerization, using (η3-allyl)­Pd­(i-Pr3P)Cl activated by [Li­(OEt2)2.5]­B­(C6F5)4 as the initiator. Both series of polymers are cast into the selective skin layers of thin film composite (TFC) membranes, and these organophilic membranes are investigated for the concentration of n-butanol from dilute aqueous solution via pervaporation. The block copolymers show well-defined microphase-separated morphologies, both in bulk and as the selective skin layers on TFC membranes, while the random copolymers are homogeneous. Both block and random vinyl addition copolymers are effective as n-butanol pervaporation membranes, with the block copolymers showing a better flux-selectivity balance; the optimal block copolymer, containing 19 wt % BuNB, showed a process separation factor of 21 and a flux of 4300 g m–2 h–1 with a 1.00 wt % aqueous n-butanol feed, at a selective layer thickness of 1.3 μm. While polyHFANB has much higher permeability and selectivity than polyBuNB, incorporating BuNB units into the polymer (in either a block or random sequence) limits the swelling of the polyHFANB and thereby improves the n-butanol pervaporation selectivity. An analogous block copolymer derived from ring-opening metathesis polymerization, which shows much greater swelling than the vinyl addition polymers, shows a correspondingly higher flux and lower selectivity.

The structure and mechanical properties of a novel block copolymer (BCP) system with T(g)'s for both segments exceeding 300 °C, poly(butylnorbornene)-block-poly(hydroxyhexafluoroisopropyl norbornene) (BuNB-b-HFANB), are investigated as a function of processing conditions used for solvent vapor annealing (SVA). Solvent selection impacts long-range order markedly, but unexpectedly vertical orientation of cylinders are preferred over a wide range of solubility parameters, as determined by atomic force microscopy and grazing incidence small-angle X-ray scattering. The mechanical properties (elastic modulus, fracture strength, and onset fracture strain) are dependent upon the long-range order induced during SVA and determined using the combination of surface wrinkling and cracking. The modulus and fracture strength of the films increase from 1.44 GPa and 12.1 MPa to 1.77 GPa and 17.5 MPa, respectively, whereas the onset fracture strain decreases from 1.6% to approximately 0.6% as the ordering is improved. The polarity difference in the segments of the BCP is attractive for membrane separations, especially butanol-water. For biobutanol recovery, the titers are typically <3 wt % butanol; exposure of the BCP membrane to aqueous 1 wt % butanol decreases the elastic modulus to approximately 0.90 GPa, irrespective of the morphology, despite the high T(g) of both segments and limited swelling (5.0 wt %). Correspondingly, the onset fracture strain of these swollen films is estimated to increase significantly to 6-7%. These results indicate that operating conditions impact the mechanical performance of BCP membranes more than their morphology despite the high T(g) of the neat copolymer. Wrinkling and cracking provide a facile route to test the mechanical properties of membranes under simulated operando conditions.