Very little is known about some fundamental issues such as the spacer length influence and molecular weight (MW) effect of discotic liquid crystalline polymers (DLCPs), despite the elucidation of such aspects are of crucial importance for their structure tuning and device performance. Here in this article, a systematic comparative study has been conducted to investigate the MW effect and especially gain a deeper insight into the spacer length influence of side-chain DLCPs based on a homologous series of well-defined discotic liquid crystalline polyacrylates with triphenylene (TP) side groups of variant spacer lengths. The series DLCPs of shorter spacers display various well-organized columnar superlattices based on multicolumn bundles organization with "coordination number" from two to six through individual discogens or discrete columnar stack (DCS)-based intracolumnar stacking modes. It is disclosed for the first time that the positive coupling effect (PCE) prevails in side-chain DLCPs, and proper coupling between discotic side groups and polymer backbone is desirable and required for achieving well-organized ordered columnar mesophases, in striking contrast with the renowned classical spacer decoupling principle directing the fruitful exploration of their side-chain calamitic counterparts for several decades. These findings are inspiring for in-depth understanding of self-assembly of aromatic interactions involved complex functional chemical and biological systems and especially opening an avenue for rational design and synthesis of well-controlled side-chain DLCPs for low-cost solution processable optoelectronic device applications.

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Poly(ether urethane)s (PEUs) are widely used as blood‐contact biomaterials because of their good biocompatibility and mechanical properties. Nevertheless, their blood compatibility is still not adequate for more demanding applications. Surface modification is an effective way to improve blood compatibility and retain bulk properties of biomaterials. The purpose of the present study was to design and synthesis a novel non‐thrombogenic biomaterial by modifying the surface of PEU with zwitterionic monomer. In this study, sulfobetaine was grafted onto PEU surface through the following reaction steps: (1) Poly(propylene oxide) (PPO) was reacted at both chain ends with hexamethylene diisocyanate (HDI), and OCN–PPO–NCO was obtained; (2) OCN–PPO–NCO was reacted at one chain end with N,N‐dimethylethanolamine (DMEA) and OCN–PPO–N(CH3)2 was formed; (3) the sulfobetaine was prepared by a ring‐opening reaction between OCN–PPO–N(CH3)2 and 1,3‐propanesultone (PSu); (4) the sulfobetaine was grafted onto PEU surface by the reaction between NCO and the N–H bonds of PEU. The surface composition of films and the hydrophilicity on the PEU surface were investigated by X‐ray photoelectron spectroscopy analysis and contact angle measurements, respectively. The blood compatibility of PEU was evaluated by platelet‐rich plasma contact experiments and the results were observed by scanning electron microscopy. The state of platelet adhesion and shape variation for the attached platelets was described. The modified surface showed excellent blood compatibility, featured by low platelet adhesion. Copyright © 2003 Society of Chemical Industry

Mechanical roughening reportedly had a weakening effect on bond strength. Therefore, the purpose of this study was to evaluate the effect of an alternative surface roughening method, namely oxygen plasma treatment, on the tensile bond strength between denture base resin and soft liner. The soft liner used in this study was Soft Reverse, whilst the denture base material was Zi Ran. Three groups of specimens were prepared, comprising untreated specimens and oxygen plasma-treated specimens with exposure to air for 1 day and 2 days. All specimens were subjected to surface composition analysis and tensile bond strength testing. All data were analyzed using one-way ANOVA, and their mean values were compared using Tukey's HSD test (p<0.01). Highest tensile bond strength was observed in the 1-day exposure group (5.2 MPa), whilst the lowest in the control group of untreated specimens (2.8 MPa). Hence, results of this study clearly indicated that oxygen plasma treatment was effective in enhancing tensile bond strength.

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