Synthesis of trans-aconitic acid molecularly imprinted polymers in [bmim][BF4] and [bmim][PF6] under photochemical (5 degrees C, AIBN) and thermal (60 degrees C, AIBN) conditions gave polymer micro-spheres (<200 nm), under bulk and precipitation polymerisation conditions, and higher selectivity indices (100% improvement) relative to the more traditional precipitation polymerisation (CH3CN, high solvent volumes) approach.

The selectivity and rebinding capacity of molecularly imprinted polymers selective for propranolol (1) using the room temperature ionic liquids [BMIM][BF4], [BMIM][PF6], [HMIM][PF6] and [OMIM][PF6] and CHCl3 were examined. The observed IF (imprinting factor) values for MIPBF4, MIPPF6 and MIPCHCl3 were 1.0, 1.98 and 4.64, respectively. The longer chain HMIM and OMIM systems returned lower IF values of 1.1 and 2.3, respectively. MIPPF6 also showed a 25% binding capacity reduction vs. MIPCHCl3 (5 μmol g(−1)vs. 7 μmol g(−1) respectively). MIPCHCl3 and MIPPF6 differed in terms of BET surface area (306 m(2) g(−1)vs. 185 m(2) g(−1)), pore size (1.10 and 2.19 nm vs. 0.97 and 7.06 nm), the relative number of pores (Type A: 10.4 vs. 7.5%; Type B: 8.5 vs. 3.0%), and surface zeta potential (−37.9 mV vs. −20.3 mV). The MIP specificity for 1 was examined by selective rebinding studies with caffeine (2) and ephedrine (3). MIPPF6 rebound higher quantities of 2 than MIPCHCl3, but this was largely due to non-specific binding. Both MIPCHCl3 and MIPPF6 showed a higher affinity for 3 than for 2. Reduction in the Room Temperature Ionic Liquid (RTIL) porogen volume had little impact on the polymer morphology, but did result in a modest decrease in IF from 2.6 to 2.3 and in the binding capacity (30% to 19%). MIPCHCl3 retained the highest template specificity on rebinding from CHCl3 (IF = 4.6) dropping to IF = 0.6 in MeOH/[BMIM][PF6]. The MIPCHCl3 binding capacity remained constant using CHCl3, CH2Cl2 and MeOH (46–52%), dropped to 6% on addition of [BMIM][PF6] and increased to 83% in H2O (but at the expense of specificity with IFH2O = 1.4). MIPPF6 rebinding from MeOH saw an increase in specific rebinding to IF = 4.9 and also an increase in binding capacity to 48% when rebinding 1 from MeOH and to 42% and 45% with H2O and CH2Cl2, respectively, although in the latter case the increased capacity was at the cost of specificity with IFCH2Cl2 = 1.2. Overall the MIPPF6 capacity and specificity were enhanced on addition of MeOH.

Molecularly imprinted polymers (MIPs) were generated for trans-aconitic acid 1 and cocaine 2 in a variety of porogens (CH3CN, CHCl3, [bmim][BF4], and [bmim][PF6]). MIP synthesis in either [bmim][BF4] or [bmim][PF6] resulted in significant acceleration of polymerization rates and, in the case of low temperature polymerizations, reactions were complete in less than 2 h, while no product was observed in the corresponding volatile organic carbon (VOC) porogen. In all instances, MIPs generated in [bmim][BF4] or [bmim][PF6] returned imprinting selectivities (I values) on par with or better than the corresponding MIP generated in VOCs. Imprinting values ranged between I = 1 and 2.9, with rebinding limited to 1 h. MIP synthesis conducted at low temperature (5°C) afforded the highest I values. Scanning electron microscopy examination of MIP morphology highlighted an unexpected template effect with MIP structure varying between discrete nanoparticles and robust monoliths. This template–monomer interaction was also observed in the rates of polymerizations with differences noted in reaction times for 1 and 2 MIPs, thus providing indirect conformation of our previously proposed use of molecular modelling–nuclear magnetic resonance titrations (the MM-NMR method) in the design phase of MIP generation. In addition, considerable batch-to-batch rebinding selectivities were observed.

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Metal-assisted chemical etching (MACE) is an inexpensive, simple method for etching silicon structures, including the etching of high aspect ratio grooves. We improve on the best reported results in this area by etching grooves with aspect ratios of 65 (vertical depths 650 µm) in n-type silicon. The grooves maintain an excellent degree of verticality and show minimal width variation. We elucidate some limiting factors and demonstrate the effect of silicon surface roughness on the groove etching.