This review focuses on a somewhat unexplored strand of regenerative medicine, that is in situ tissue engineering. In this approach manufactured scaffolds are implanted in the injured region for regeneration within the patient. The scaffold is designed to attract cells to the required volume of regeneration to subsequently proliferate, differentiate, and as a consequence develop tissue within the scaffold which in time will degrade leaving just the regenerated tissue. This review highlights the wealth of information available from studies of ex-situ tissue engineering about the selection of materials for scaffolds. It is clear that there are great opportunities for the use of additive manufacturing to prepare complex personalized scaffolds and we speculate that by building on this knowledge and technology, the development of in situ tissue engineering could rapidly increase. Ex-situ tissue engineering is handicapped by the need to develop the tissue in a bioreactor where the conditions, however optimized, may not be optimum for accelerated growth and maintenance of the cell function. We identify that in both methodologies the prospect of tissue regeneration has created much promise but delivered little outside the scope of laboratory-based experiments. We propose that the design of the scaffolds and the materials selected remain at the heart of developments in this field and there is a clear need for predictive modelling which can be used in the design and optimization of materials and scaffolds.

Uniaxially oriented samples of thermotropic random copolyesters of hydroxybenzoic and hydroxynaphthoic acids, and of hydroxybenzoic acid and ethylene terephthalate, have been characterised in detail using wide-angle X-ray diffraction. The technique was used to measure the global chain orientation, and in the case of the first polymer the meridional scattering has been analysed in terms of diffraction from an isolated straight random chain. Optical microstructures were observed between crossed polars, with circularly polarized light and in plane-polarised light with no analyser present. Interpretation of the contrast seen shown that the material is optically biaxial and leads to the conclusion that, in the liquid-crystalline phase, there is long-range correlation of the rotations of the molecules about their chain axes. The polymers are examples of ‘biaxial nematics’. Thermal analysis indicates that the solid phase has a higher level of conformational order than the melt and that the melting range is very broad. Annealing below the melting point leads to the development of localised regions of enhanced order, especially in specimens with a high degree of overall orientation. The combination of electron diffraction and electron microscopy provides evidence that the lateral growth of ordered entities does not necessarily require regular sequences within the otherwise random copolymer molecules. Small crystals based on identical but non-periodic sequences within the molecules are (NPL crystals) proposed as being consistent with the experimental evidence and the implications of a brief statistical analysis.

A novel strain-induced transition of the director orientation in a monodomain cross-linked side-chain liquid-crystal polymer system is reported which is analogous to the Fréedericksz transition in simple nematics. This new type of transition has a characteristic threshold strain which arises from an internal elastic barrier to rotation and is related to the level of anisotropy of the polymer chain trajectory.