We would like to dedicate this article to P. H. Plesch, a pioneer of cationic polymerization and a mentor and friend for many of those who are now at the forefront of this field of science. He passed away 5 March 2013 at the age of 95. We will miss him. Abstract: This short, introductory review covers the still rapidly growing and industrially important field of ring opening polymerization (ROP). The review is organized according to mechanism (radical ROP (RROP), cationic ROP (CROP), anionic ROP (AROP) and ring-opening metathesis polymerization (ROMP)) rather than monomer classes. Nevertheless, the different groups of cyclic monomers are considered (olefins, ethers, thioethers, amines, lactones, thiolactones, lactams, disulfides, anhydrides, carbonates, silicones, phosphazenes and phosphonites) and the mechanisms by which they can be polymerized involving a ring-opening polymerization. Literature up to 2012 has been considered but the citations selected refer to detailed reviews and key papers, describing not only the latest developments but also the evolution of the current state of the art.

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poly(2-methylpropene) (PIB) macromonomers (P3 (VB); P5) is described:In this communication a novel synthetic route to a-tert-butyl-o-[p-vinylphenyll-terminated and P5Attempts to synthesize such macromonomers in both one-and two-step syntheses are described. The one-step method using 4-chloromethylstyrene/AlR3 as initiating system for the polymerization of 2-methylpropene did not yield linear macromonomers but rather highly branched products. The alternative two-step synthesis using l-(2-bromoethyl)-4-chloromethylbenzene (BCB) or BCB/AgSbF, as initiator also failed to yield the desired products. Successful synthetic routes, optimised on the basis of model experiments with low molar mass compounds, are also described for preparing the above macromonomers. Both of these routes involve isopropenylterminated PIB, which is easily assessible by Inifer technique followed by dehydrohalogenation. Friedel-Crafts alkylation of phenol by the terminal olefin group of PIB, followed by subsequent esterification of the phenolic end-groups with 4-vinylbenzoyl chloride, affords the macromonomer P3(VB). Conversion of the terminal olefin group of PIB into a primary alcohol using 9-bora[3,3, I]-bicyclononane/H202, followed by esterification, yields the macromonomer P5. ' ) BASF,

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The preparation of reactive polyurethanes, the photopolymerization, and copolymerization of acrylates in emulsion as well as solution and the precipitation and reactive precipitation to prepare BaSO4 and silver nanoparticles, respectively, employing a spinning disk reactor (SDR) are summarized. The advantages of an SDR (excellent mass and heat transfer, minimal energy, and material usage, easy scale up as well as flexibility) are discussed. Where experiments are described comparing the SDR with traditional batch processes, known, optimized industrial batch processes are chosen. In all cases, the SDR could be shown to yield equivalent product quality while having procedural advantages.

The cationic polymerization of isobutene by the "inifer"-technique was studied. Preliminary experiments are described which suggest that useful polymer can be prepared only when BCI, is rapidly added to the premixed monomer/inifer mixture and that such polymerizations do not go to completion. Some questions regarding the mechanism are discussed and remain open.0025-1 16X/83/$03 .OO

Experimental details are given of attempts to enumerate the binary ionogenic equilibria (B.I.E.) of i-chloro-1-methylethylbenzene (l)/BC13, 1,4-bis(l-chloro-l-methylethyl)benzene (2)/BCI3 and 1,3,5-tris(l -chloro-I methylethy1)benzene (3)/BCI3 in CH2C12. Due to chemical reaction (dimerisation or polymerisation) no experimental values for the B.I.E. constants could be obtained. A Born-Haber cycle is constructed to estimate the relative sequence of the overall B.I.E. constants. A similar treatment for 2-chloro-2-methylpropane as a thermodynamic model for a,w-dichloropoly(2-methylpropene) (4) suggests that the overall B.I.E. constant for these polymers is somewhat smaller than those for 1 and 2 but greater than that for 3. Using 2/BCI3 as initiator for the polymerisation of 2-methylpropene(IB) it is shown, that the degree of polymerisation of 4 can be controlled within the limits 10 < DP < 100. It is shown that 4 can also act as an initiator for the polymerisation of IB, that these polymerisations involve only free ion propagation and, from a kinetic analysis of these polymerisations, that: (kp'y/kc = 12 1 . mol-' . s -' , kZt = 1,2~10-31.mol-'~s-',k,+[P,+] = 1,7.1O-,s-',andk,+/(k:~,5) = 102.Thesame analysis demonstrates that the self-ionisation of BCI, can be neglected in terms of any influence on the molar mass of the products. Experiments are also described which show that 2-chloro-2methylpropane is not suitable as a substitute initiator for IB, but that 2-chloro-2,4,4-trimethylpentane is a useful model for 4 as an initiator for the polymerisation of IB. CI transfer J via Zd -2c[.20) --------4 *) The nomenclature for the B.I.E. constants used here is based on that suggested by Grattan and Plescd).