Amphipolar diblock copolymers used as admixtures provide a unique effect on crystallization processes from solution. In an example given here, nucleation of ZnO crystals and growth of specific crystal faces is controlled by minute amounts of PEO-b-PMAA copolymers. A narrow crystal size distribution and retardation of growth parallel to [001] are observed in dependence on the concentration of the block copolymer, which is added in the ppm range.

Today, there is an increasing concern about protection of ecological systems. Petro-based synthetic polymers are not biodegradable and cause environmental pollution. These polymers that are stuck in nature, affect wildlife adversely. Also, in future petrochemical materials will drain away and demand for ecofriendly plastics which can substitute synthetic plastics will increase. Biopolymers are products which can be degraded by enzymatic activities of various microorganisms, and the degradation products are nontoxic. They are attractive alternatives to non-degradable materials in short-term applications such as packaging. Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is a member of polyhydroxyalkanoate (PHA) family which is biodegradable and produced by microorganism. It has good gas barrier properties that make it convenient to use in different applications. The present paper gives an overview on PHAs and their composites, their main properties, with a specific focus on potential applications of PHBV in packaging.

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In this study, the effect of phosphonate additives on the crystallization of calcium sulfate dihydrate (CaSO 4 3 2H 2 O, gypsum) has been investigated in aqueous solutions. Ethylenediamine-tetrakis(methylenephosphonic acid) (EDTMP), hexamethylenediamine-tetrakis(methylenephosphonic acid) (HDTMP), octamethylenediamine-tetrakis-(methylenephosphonic acid) (ODTMP), and dodecamethylenediamine-tetrakis(methylenephosphonic acid) (DDTMP) have been used as additives. It was found that they are very effective retardants for the crystallization of calcium sulfate dihydrate. The inhibition efficiency is directly proportional to the number of methylene groups in the organic chain that connects the aminobis(methylenephosphonate) moieties. The degree of inhibition of crystallization was measured as an increase in induction time and reduction in crystallization rate. Particle size and crystal morphology were determined with a particle-sizer and scanning electron microscopy. According to experimental results, phosphonate additives tested in this study are very effective retardants for the formation of calcium sulfate dihydrate scale. The crystal structure of [Ca(EDTMP)(H 2 O) 2 ] 3 H 2 O is also reported. This is a one-dimensional coordination polymer in which EDTMP acts as both a bidentate chelate and a bridge for Ca 2þ centers.

In this work, the effect of a biodegradable, environmentally friendly polysaccharide-based polycarboxylate, carboxymethyl inulin (CMI), on the crystal growth kinetics of calcium oxalate was studied at 37 °C. CMI is produced by carboxymethylation of inulin, the latter extracted from chicory roots. The spontaneous crystallization method was utilized to investigate the crystallization kinetics of calcium oxalate (CaC 2 O 4 , CaOx). The experimental results show that the retardation in mass transport in the growth process is controlled by the carboxylation degree of CMI and also its concentration. Our studies also indicate that polymers were effective in directing calcium oxalate crystallization from calcium oxalate monohydrate (COM) to calcium oxalate dihydrate (COD). Comparisons with the effects of polyacrylate (PAA) additive, which was also included in our experiments, show that PAA is a more effective inhibitor than CMI-15 and CMI-20, and comparable to CMI-25.