Boer, Albert de

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Proceedings - University of Groningen

   University of GroningenAssociations of stereoregular polymethylmethacrylatesBoer, Albert deIMPORTANT NOTE: You are advised to consult the publisher's version (publisher's PDF) if you wish to cite fromit. Please check the document version below.Document VersionPublisher's PDF, also known as Version of recordPublication date:1976Link to publication in University of Groningen/UMCG research databaseCitation for published version (APA):Boer, A. D. (1976). Associations of stereoregular polymethylmethacrylates. s.n.CopyrightOther than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of theauthor(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons).The publication may also be distributed here under the terms of Article 25fa of the Dutch Copyright Act, indicated by the “Taverne” license.More information can be found on the University of Groningen website: https://www.rug.nl/library/open-access/self-archiving-pure/taverne-amendment.Take-down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediatelyand investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons thenumber of authors shown on this cover page is limited to 10 maximum.Download date: 01-02-2024SUI{MARYTh is  t hes i s  desc r i bes  the  assoc ia t i on  o f  s te reo regu la r  po l y (me thy l  me tha -c ry la tes )  i n  d i l u te  so lu t i ons  and  i n  bu1k .  I t  i s  known  tha t  i so tac t i c  andsyndiotact ic  poly(methyl  methacry late)  ( i -  and s-PMM) have complementarystructures and Èhat  speci f ic  in teract ions occur  between i -  and s-PMMA(Chap te r  I  )  .Stereocomplex format ion of  i -  and s-PMMA can take p lace in  d i lu te so-lut ions far  below the homogeneous segmental  d is t r ibut ion concentrat ion,which was demonstrated by means of  v iscometr ic  and turb id imetr ic  measure-men ts .  As  the  so l ven t  appea red  to  i n f l uence  cons ide rab l y  t he  deg ree  o fassoc ia t i on ,  an  emp i r i ca l  d i v i s i on  was  made  i n to  3  g roups :  A  -  s t rong l ycomp lex ing  so l ven ts  (e .g .  ace tone ,  DMF,  DMSO,  ace ton i t r i l e ,  me thy l  i so -butyrate and monomer MMA);  B -  weakly complexing solvents (e.g.  Ëolueneand  benzene ) ;  C  -  non -comp lex ing  so l ven ts  (e .g .  ch lo ro fo rm)  (Chap te r  2 ) .The  tac t i c i t y  o f  s -PMMA appea rs  t o  í n f l uence  the  assoc ia t i on  p rocessstrongly whereas a narrorder  molecular  weight  d is t r ibut ion of  i -PMl, lA haso n l y  l i t t l e  i n f l u e n c e  ( A p p e n d i x  l ) .B a s e d  u p o n  t h e  r e s u l t s  o f  d i f f e r e n t í a l  s c a n n i n g  c a l o r i m e t r y  ( d . s . c . )and X-ray powder d i f f ract ion pat terns Í íe  conclude that  in  d i lu te typeA  so lu t i ons  i -  and  s -PMMA cha ins  pa r t l y  assoc iaLe  i n  an  i / s  ra t i o  o fabou t  I  :  I  and  tha t  a t  t he  same t ime  l i qu id  i nduced  c rys ta l l i za t i on  o f  s -PI ' IMA occurs (Chapter  3)  .The rma l  ana l ys i s  showed  tha t  ma te r i a l  assoc ia ted  i n  d i l u te  t ype  A  so lu -t ions had 3 endotherms at  temperatures not  depending on the composi t iono f  t he  samp le .  The  endo the rm a t  * r  2 l 0oC  i s  caused  by  t he  me l t i ng  o f  t hes te reocomp lex ,  t he  endo the rm a t  ^ ,  l 85oC by  the  me l t i ng  o f  so l ven t  s ta -b i l ized s-PMMA, whi le  the endotherm at  ^ ,  2BOoC is  caused by the degra-da t i on  o f  PM l , lA  (Chap te r  3 ) .Associat ion of  i -  and s-PMMA can a lso occur  in  bulk  as demonstratedby means of  ca lor imetr ic  and dynamic -  mechanical  measurements.  The rateof  complex format ion is  maximal  at  l40oc and the extent  of  complex for-mat ion is  maximal  at  a composi t ion somewhat  lower than the i /s  rat io  ofII11 0 8l :  l .  The high rate of complex formation in bulk -  more than half  of  thecomplex has been formed within 2 minutes at l4OoC - is remarkable themore so as the separate components do not crystal l ize at al l  underthese cond i t ions  (Chapter  4 ) .As mechanism for complex fornat ion in bulk i t  is proposed that chainsegments of i-PMl,lA form nuclei by adopting the favourabl.e 5, helix confor-mation, whereupon chain segments of s-PM!{A associate with these favourablep laces  y ie ld ing  a  f r inged mice l le  l i ke  s t ruc tu re .  As  the  assoc ia t ion  con-t inues the crysÈal l ine regions are extended appearing from the fact thatannealed and non-annealed samples had about the same value of the sto-rage modu lus  (G ' )  above the  g lass  t rans i t ion  tempera ture  (Chapter  4 ) .In order to compare the propert ies of the stereocomplex with thoseof pure i -  and s-PMl' ÍA, the crystal l izat ion of i -  and s-PMIÍA was studied.i-PMMA is a very slowly crystal . l iz ing polymer with a maximal growth rate- ?(G =  I  x  l0 - 'U* / * in )  o f  the  c rys ta ls  aÈ t20oC,  wh i le  the  es t imated(equ i l ib r ium)  mel t ing  tenpera ture  (To)  i s  220oc  (Chapter  5 ) .  The c rys ta l -l izat ion of s-PMMA from the melt  appeared to be even more troublesome.Therefore s-PM!' ÍA was treated with borderLine solvents (heptanone-4, methylisobutyrate and toluene).  This mater ial  which had not been ful ly dr ied,showed an endotherm a t  ^ ,  lg0oC as  recorded by  d .s .c .  and a  re f lec t ion  a t2 0 = 4o3O' in the X-ray di f f ractogram. Drying the sample further resultedin the dísappearance of endotherm and ref lect ion. From this i t  may be con-cluded that some crystal l ine structure of s-PMl,IA is stabi l ized by solvent(Append ix  2 ) .IR spectroscopy showed thaÈ upon complex formation in di lute type A solu-r ions s-PMMA most ly takes on a planar structure with a gl ide plane, where-as i-PMI"ÍA has a 5, helix conformation in the stereocomplex and that. asso-ciation of i- and s-PMI"ÍA occurs over long distances along the chains. Pre-l iminary f ibre di f f ract ion measurements showed that the c axis of the unitcel l  of  the stereocomplex is ry I  I  shorter than that of  i -PMMA (Chapter 6).The difference in configuration and conformation of i- and s-PMl'íA al.soappeared to influence the mixing behaviour of PMI,ÍA and PVC Ipoly(vinylchlo-ride) I i-PlO,ÍA and PVC form an incompatible system, whereas s-PMIíA andPVC form a compatible system up to a composit ion corresponding with amonomer unic rat io of I  :  I  (PVC : s-PMMA) (Chapter 7).r e tl 5r09

Associations of stereoregular polymethylmethacrylates

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Associations of stereoregular polymethylmethacrylates

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Proceedings - University of Groningen