Semiflexible PLCs

It is clear from Figures 4 and 5 that the chain dimensions and probabilities have essentially reached their asymptotic values at modest temperatures. We should expect, therefore, that in melts of semiflexible PLCs, unless there are extreme extenuating circumstances (i. e., perfect core orientational ordering), the dimensions of a spacer chain and the conformer probability distributions within a spacer chain should be similar to those quantities in an alkane liquid. The attachment of a spacer at both ends will of course perturb the dimensions and conformer probabilities of the spacer. Clearly the magnitude of this perturbation of the spacer is the key to understanding the role of the spacer in a PLC. 

Whilst the above examples seem to indicate that miscibility is related to PLC flexibility, it would be useful to be able to blend an EP with an homologous series of semiflexible PLCs with sequentially longer spacer chains and monitor how this affects miscibility. This was reported recently by Yan and He [146] who synthesized a PLC homopolymer HQ(n)... 

There are other studies of different semiflexible PLC + semicrystalline... 

HNA/0.73PHB and a semiflexible PLC of structure similar to HTHIO but with four flexible units in the spacer, TR-4,... 

The investigations of thermotropic PLCs commenced almost two decades after studies of mesophases employing rodlike polymers(21) and virus particles(22) in solution were initiated. Like their MLC analogues (aqueous solutions of amphiphilic molecules) the polymeric lyotropic liquid crystals which form in solutions of rigid, rodlike polymers (helical biopolymers, and more recently, semiflexible aromatic amides) constitute a distinct class of liquid crystals. Unlike the MLC analogues, however, the lyotropic PLCs are not necessarily stabilized by specific interactions between the polymer chain... 

Blends of semiflexible longitudinal PLCs PET/xPHB copolyesters... 

Whilst blends of various engineering thermoplastics with PET/0.6PHB are perhaps the most commercially relevant of semiflexible, longitudinal PLC blends, it is of interest to review work done where the flexibility and chemical structure of the semiflexible material is altered and structure-property relations with regards to miscibility, interfacial adhesion and crystallization phenomena determined. This section will discuss blends in terms of the structure of the PLC, rather than the EP with which they are blended. 

Pad ei al. [142] blended a semiflexible, longitudinal PLC copolymer of poly (biphenyl-4,4 -ylene sebacate) (PBS) with chemical structure... 

For the purpose of discussing mesophase formation in polymers it is conveiuent to partition the polymers into two categories and introduce abbreviations that refer to these categories. Polymerized liquid crystals, here abbreviated PLCs, are derived from known, low molecular weight monomer liquid crystals (MLCs) that contain polymerizable functionality (e.g. vinyl units). We designate liquid-crystalline polymers (LCPs) to be semiflexible, linear polymers that are structurally related to conventional engineering thermoplastics, i.e. polymers derived from poly(ester)s, poly(amide)s, poly(imide)s, etc. We will examine the attributes of polymerized liquid crystals first, stressing the similarities between their properties and those of MLCs. 

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