Dipolar glass (DG) polymers, which utilize sub-T g orientational polarization (T g is the glass transition temperature) to enhance dielectric constants, are promising candidates for use in advanced electronic and power applications because conduction of space charges (electrons and impurity ions) is suppressed in the glassy state, and thus, the dielectric loss is low. In this study, we studied the effects of dipole density and dipole arrangement in sulfonyl-containing side-chain DG polymers on their dielectric performance in terms of dielectric constant, energy density, and dielectric loss. Monosulfonyl (i.e., CH 3 SO 2 -) and disulfonyl [i.e., CH 3 SO 2 (CH 2 ) 3 SO 2 -] groups were quantitatively grafted to polyepichlorohydrin (monosubstitution) and poly(3,3bis(chloromethyl)oxatane) (bis-substitution), respectively, in order to vary the dipole density and dipole arrangement in the side chains. As a result of orientation polarization from highly polar sulfonyl (4.5 D) groups, these DG polymers exhibited high apparent dielectric constants (7−11.5) in the glassy state with reasonably low dissipation factors (tan δ ∼ 0.003−0.02). It was found that disulfonylated DG polymers exhibited a higher dielectric constant than monosulfonylated DG polymers because of their higher dipole densities. Meanwhile, bis-substituted DG polymers showed a higher dielectric constant than monosubstituted DG polymers. Upon high-field electric poling, reversible transitions between the low-field DG state and the high-field ferroelectric state induced double hysteresis loops, and disulfonylated DG polymers had more significant ferroelectric switching than monosulfonylated DG polymers due to stronger dipolar interactions among the disulfonyl groups. On the basis of the experimental results, monosulfonylated DG polymers, whether mono-or bis-substituted, should be more appropriate for electric energy storage applications.

Mesogen-jacketed liquid-crystalline polymers (MJLCPs) containing two triphenylene (Tp) units in the side chains, denoted as PPnV (n = 3 or 6, which is the number of the methylene units between the terephthalate core and Tp moieties in the side chains), were synthesized through conventional free radical polymerization, and the phase behaviors of these new combined main-chain/side-chain liquid-crystalline (LC) polymers were investigated. The chemical structures of the monomers were confirmed by elemental analysis, high-resolution mass spectrometry, and 1H/13C NMR. The molecular characterizations of the polymers were performed with 1H NMR, gel permeation chromatography, and thermogravimetric analysis. LC behaviors of the polymers were investigated by differential scanning calorimetry (DSC), polarized light microscopy, and wide-angle X-ray diffraction (WAXD). Both polymers exhibit excellent thermal stabilities. DSC and WAXD results indicate that covalently incorporating Tp discotic liquid crystals has a tremendous effect on the LC behaviors of MJLCPs. As expected, the glass-transition temperature decreases as the spacer length increases. Both polymers form rectangular columnar (ΦR) phases at relatively high temperatures. At low temperatures, however, Tp moieties in the side chains form a discotic nematic (ND) phase in conjunction with the ΦR phase developed by the rod-like supramolecular mesogen – the MJLCP chain as a whole, owing to the self-organization of the Tp moieties. For PP6V in particular, a higher symmetry hexagonal columnar (ΦH) phase forms when temperature exceeds 225 °C. Individual ordered structures developed by these two LC building blocks are not only competitive but also promotive to each other.

The concept of slippery lubricant-infused surfaces has shown promising potential in antifouling for controlling detrimental biofilm growth. In this study, non-toxic silicone oil was either impregnated into porous surface nanostructures, referred as liquid infused surface (LIS), or diffused into a polydimethylsiloxane (PDMS) matrix, referred to as a swollen PDMS (S-PDMS), making two kinds of slippery surfaces. The slippery lubricant layers have extremely low contact angle hysteresis and both slippery surfaces showed superior anti-wetting performances with droplets bouncing off or rolling transiently after impacting the surfaces. We further demonstrated that water droplets can remove dust from the slippery surfaces thus showing a "cleaning effect". Moreover, "coffee-ring" effects were inhibited on these slippery surfaces after droplet evaporation, and deposits could be easily removed. The clinically biofilm-forming species P. aeruginosa (as a model system) was used to further evaluate the antifouling potential of the slippery surfaces. The dried biofilm stains could still be easily removed from the slippery surfaces. Additionally, both slippery surfaces prevented around 90% of bacterial biofilm growth after 6 days, compared to the unmodified control PDMS surfaces. This investigation also extended across another clinical pathogen, S. epidermidis, and showed similar results. The anti-wetting and anti-fouling analysis in this study will facilitate the development of more efficient slippery platforms for controlling biofouling.

Biofilms are central to some of the most urgent global challenges across diverse fields of application, from medicine to industries to the environment, and exert considerable economic and social impact. A fundamental assumption in anti-biofilms has been that the coating on a substrate surface is solid. The invention of slippery liquid-infused porous surfaces—a continuously wet lubricating coating retained on a solid surface by capillary forces—has led to this being challenged. However, in situations where flow occurs, shear stress may deplete the lubricant and affect the anti-biofilm performance. Here, we report on the use of slippery omniphobic covalently attached liquid (SOCAL) surfaces, which provide a surface coating with short (ca. 4 nm) non-cross-linked polydimethylsiloxane (PDMS) chains retaining liquid–surface properties, as an antibiofilm strategy stable under shear stress from flow. This surface reduced biofilm formation of the key biofilm-forming pathogens Staphylococcus epidermidis and Pseudomonas aeruginosa by three–four orders of magnitude compared to the widely used medical implant material PDMS after 7 days under static and dynamic culture conditions. Throughout the entire dynamic culture period of P. aeruginosa , SOCAL significantly outperformed a typical antibiofilm slippery surface [i.e., swollen PDMS in silicone oil (S-PDMS)]. We have revealed that significant oil loss occurred after 2–7 day flow for S-PDMS, which correlated to increased contact angle hysteresis (CAH), indicating a degradation of the slippery surface properties, and biofilm formation, while SOCAL has stable CAH and sustainable antibiofilm performance after 7 day flow. The significance of this correlation is to provide a useful easy-to-measure physical parameter as an indicator for long-term antibiofilm performance. This biofilm-resistant liquid-like solid surface offers a new antibiofilm strategy for applications in medical devices and other areas where biofilm development is problematic.